Some Factors Influencing the Activity of Raney Nickel Catalyst
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PURDUE UNIVERSITY
TH IS IS TO CERTIFY THAT T H E T H E S IS PR EPA R ED U ND ER MY S U P ^ T I S I O N
BY_________ Y o sh lk a zu Yamada
ENTITLED
SOME FACTORS im U B îIC lïïC THE ACTIVITY OP RAHRY EICKRL CATALYST
COM PLIES W ITH T H E UNIVERSITY REGULATIONS O N GRADUATION T H E S E S
AND IS APPROVED BY ME A S FU LFILL IN G TH IS PART O F TH E REQUIREM ENTS
F O R T H E D EG R EE O F
D o c to r o f P h ilo s o p h y
éj--------------
ProfbssorI» Chahoe or Thbbis
Hear or Sohooi. orDzpARTMRwr
.Pabruary,___ î»5û_
TO T H E LIBRARIAN:---IS > »•+• TH IS T H E SIS TO B E REGARDED A S CONFIDENZlAI«.
GSAD. SOBOCXb FOBX • —8 .4 » - l X
SOME PAO TORS IIÎPLUEHOIITG THE ACTIVITY OP RAÎ3BY NICKEL CATALYST A T lie s is S u b m itte d t o t h e P a o u l t y of P u rdu e U n i v e r s i t y by Y o sh lk a z u Yâmada I n P a r t i a l F u l f i l l m e n t o f th e R e q u ire m e n ts f o r th e D egree of D o c to r o f P h i lo s o p h y F e b r u a r y , 1960
ProQuest Number: 27712226
All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is d e p e n d e n t upon the quality of the copy subm itted. In the unlikely e v e n t that the a u thor did not send a c o m p le te m anuscript and there are missing pages, these will be noted. Also, if m aterial had to be rem oved, a n o te will ind ica te the deletion.
uest ProQuest 27712226 Published by ProQuest LLO (2019). C opyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C o d e M icroform Edition © ProQuest LLO. ProQuest LLO. 789 East Eisenhower Parkway P.Q. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346
AOKNOWLSDGMENT
The a u t h o r w is h e s t o e x p r e s s h i s g r a t i t u d e t o D r. Edward F r a n k l i n Deg e r i n g , who d i r e c t e d t h i s w ork, f o r h i s p a t i e n t and s k i l l f u l g u id a n c e and to ackno?/ledge th e f i n a n c i a l s u p p o r t o f t h e Harshaw C hem ical Company and t h e P u rdu e R e s e a r c h F o u n d a tio n w h ich made t h i s s tu d y p o s s i b l e .
TABLE OF CONTB®TS Page ABSTRACT
P a rt 1.
The E f f e c t of L i q u i d Volume on t h e R a te o f L iq u id P h a s e H y d r o g e n a t i o n ........................
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P art 2.
The E f f e c t of L i q u i d Volume and t h e Amount o f C a t a l y s t on t h e R a te o f L iq u id P hase H y d ro g en at i o n . ......................................... x i v
P a rt 3.
The E f f e c t o f H ydrogen on Raney N i c k e l C a t a l y s t ..........................................................................
INTRODUCTION............................................................................................ PART 1 .
1
DEVELOBŒNT OF AN ACTIVITY TEST
In tro d u c tio n
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E x p e r im e n t a l A p p a r a tu s and P r o c e d u r e . « •
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M a t e r i a l s ................................ M easurem ent o f t h e Amount o f C a t a l y s t .
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R e p r o d u c i b i l i t y of H y d r o g e n a tio n Runs. . . .
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E f f e c t o f T e m p e r a tu r e ......................................................... 14 'R e s u lts an d ;D isc u ssio n Hydro g e n a t i o n C urves a n d t h e M easure o f A c t i v i t y ............................................................................ 17 E f f e c t o f L i q u i d Volume.....................................................SO E f f e c t o f t h e Amount o f C a t a l y s t . . . . . .
24
S u g g e s te d P r o c e d u r e f o r C a t a l y s t T e s t i n g . .
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S u m m a r y ...............................................................................................30 PART I I .
THE PREPARATION OF RANEY NICPCEL CATALYST AND SOME FACTORS INFLDENCINC THE ACTIVITY OF THE CATALYST
I n t r o d u c t i o n ............................ ................................................... .......
Page E x p e rim en tal P rocedure
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R e s u l t s an d D i s c u s s i o n E f f e c t o f Hydrogen on C a t a l y s t ................................................... P re p a ra tio n s. .
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E f f e c t o f a O o m bln atio n o f T em peratu re Change and Hydrogen on th e A c t i v i t y o f th e C a t a l y s t .......................
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Age
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D e n s ity . . . . . . Summary. PART I I I .
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THE EFFECT OF JslQMID VOLm!E AÎTD THE AMCUITT OF OATAIYST OH THE RATE OF LI^iUIE- P7TASE 1.YDROOEHATION
In tro d u c tio n .
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P rin c ip le s . . . . . E x p e r im e n ta l . . . . . .
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R e s u l t s and D i s c u s s i o n . ...................
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Summary.......................................... PART IV .
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DEVELOPPENT AND APPLIOATIOH OF AN EMPIRICAL EG^HATION FOR EYDROGEN 00E3UIE2TI0N..............................75
BIBLIOGRAPHY....................................................... VITA
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LIST OF TABLES T ab le 1
Page O onstanoy o f P r o d u c t Formed a t D i f f e r e n t H a te s o f H y d ro g e n a tio n .............................
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9
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R e p r o d u c i b i l i t y o f H y d ro g e n a tio n Runs. • . • • «
3
In d e p e n d e n c e o f H y d ro g e n a tio n V e l o c i t y o f t h e I n i t i a l M ix tu r e T e m p e r a t u r e ..............................16
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E f f e c t o f L iq u i d Volume and th e Amount o f C a t a l y s t on th e R a t e . . . . . .
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£8
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Number o f P a r t i c l e s p e r U n i t Volume and th e E f f e c t i v e S u r f a c e A rea ..............................55
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E f f e c t S u r f a c e Area f o r a C o n s t a n t Amount o f C a t a l y s t w i t h D e c re a s e i n L i q u i d Volume . .
66
7
P r e d i c t e d H y d ro g e n a tio n R a te s o f D i f f e r e n t Amounts o f S t y r e n e o v e r E x 0 . 9 g . M o is t W eight o f C a t a l y s t l I i ( R ) l - 7 S ............................................61
8
H y d ro g e n a tio n R a te s o f D i f f e r e n t Amounts o f S ty r e n e o v e r Two L e v e l S p o o n s f u l o f M ( R ) l - 7 3 ....................................................
9
10
11 IE
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H y d ro g e n a tio n R a t e s o f D i f f e r e n t Amounts o f a M ix tu re of S t y r e n e - E t h a n o l i n 1:E P a r t s by Volume.........................................................
64
C a l c u l a t e d and E x p e r im e n ta l H y d ro g e n a tio n R a t e s o v e r c a . l / E x 1 .1 6 g. o f Raney N ic k e l C a t a l y s t . . ...................... . . . . . . . . E f f e c t o f I n e r t S o l i d s i n th e H y d ro g e n a tio n R ate of S t y r e n e ................................
66 .
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E f f e c t o f L i q u i d Volume on t h e H y d ro g e n a tio n R a te o f S t y r e n e ............................................78
LIST OF FIGURES F ig u r e
Page
1.
R e p r o d u o i b i l i t y o f H y d r o g e n a tio n Runs .........................
12
2.
R e p r o d u o i b i l i t y o f H y d ro g e n a tio n R u n s ........................
13
3.
Hydrogen P r e s s u r e an d T em p e ratu re C hanges i n t h e H y d ro g e n a tio n of S t y r e n e . . . . . . .
15
4.
The S hapes o f H y d ro g e n a tio n C u r v e s ..................................
18
5.
E f f e c t o f R e s t o r i n g Hydrogen to I t s I n i t i a l P ressure .........................
19
Change in H y d r o g e n a tio n R ate w i t h Volume o f S ty re n e . . . . . . . . . . . .
21
E f f e c t o f S th y lb e n z e n e on th e Hydro g e n a t i o n R ate o f S t y r e n e ....................................................
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E f f e c t o f E t h a n o l on th e H y d ro g e n a tio n R ate o f S t y r e n e ............................................................
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E f f e c t o f Age on a C a t a l y s t .............................
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E f f e c t o f t h e Amount o f C a t a l y s t on th e H y d r o g e n a tio n R a t e ...............................................................
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E f f e c t o f t h e Amount o f C a t a l y s t on th e H y d r o g e n a tio n R a t e . .....................................
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Com parison o f Two Raney N i c k e l P r e p a r a t i o n s . . .
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A c tiv ity T e sts . . .
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R e a c tiv a tio n o f a C a ta ly s t. . . . . . . . . . . .
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R e a c tiv a tio n of a C a ta ly s t. . . . . . . . . . . .
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K eep in g Q u a l i t y o f C a t a l y s t i n a L i q u i d U nder H y d r o g e n .........................
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K e e p in g Q u a l i t y o f C a t a l y s t i n a L i q u i d Under Hydrogen P r e s s u r e . . . . . . . . . . . .
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E f f e c t o f R apid C o o lin g o f C a t a l y s t i n Open A i r . . . . . . . . . .
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6. 7. 8. 9. 10. 11.
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E f f e c t o f G radu al C o o lin g o f C a t a l y s t Under Hydrogen P r e s s u r e ............................
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Page
Figure SO. 21.
22. 23. 24.
25. 26. 27. 28.
R e l a t i v e S u r f a c e E x p o su re B ased on S p h e r i c a l P a r t i c l e s ......................................
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53
T h e o r e t i c a l C u rv es Showing Change i n R a te w i t h 50^ D e c re a s e o r 100^ I n c r e a s e i n t h e Amount o f C a t a l y s t . . ...........................................
57
G r a p h i c a l D e t e r m i n a t i o n o f th e Optimum Volume . . . . . . . . . . .
60
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C a l c u l a t e d and E x p e r i m e n t a l H y d ro g e n a tio n R a t e s o f S t y r e n e ..................................... C a l c u l a t e d and E x p e r i m e n t a l H y d ro g e n a tio n R a t e s f o r 50^ D e c re a s e i n th e Amount of C a ta ly st . . . . . . . . . . . . .
62
. .
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D is p la c e m e n t o f Optimum Volume w i t h th e R e d u c tio n i n t h e Amount o f C a t a l y s t . . . . . .
70
R e la tiv e P e rio d s o f P a r t i c l e O s c illa tio n and C a t a l y t i c C ycle . . . . . . . . . . . .
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R e l a t i o n o f t h e I n s t a n t a n e o u s R a te to Time ........................ i n t h e H y d ro g e n a tio n o f S ty re n e .
76
R e la tio n of
81
t o T o t a l L i q u i d Volume
(CONTRIBUTION FROM THE DBPARTTCTT OF CHEMISTRY AND THE PURDUE RESEARCH FOUNDATION, PURDUE UNIVERSITY) S01ÆE FACTORS INFLUENCING THE ACTIVITY OF RANEY NICKEL CATALYST PART I THE EFFECT OF LIQUID VOLUME ON THE.RATE OF LIQUID PHASE EYDROGBNATIO# by y . Yamada w i t h E d. F . D e g e rin g ^ AN ABSTRACT
1.
A b s t r a c t e d from a t h e s i s s u b m i tt e d t o th e F a c u l t y o f P urd ue U n i v e r s i t y by Y. Yamada i n p a r t i a l f u l f i l l m e n t o f t h e r e q u i r e m e n t s f o r t h e d e g r e e o f D o c to r o f P h i l o s o p h y , F e b r u a r y , 1950.
2.
P resen t address: Armour R e s e a r c h F o u n d a tio n o f I l l i n o i s I n s t i t u t e o f T ech no log y, C h icag o , 111. I n a t t e m p t i n g to work o u t a s u i t a b l e p r o c e d u r e f o r t e s t i n g
th e a c t i v i t y o f Raney n i c k e l p r e p a r a t i o n s by u s i n g t h e h y d r o g e n a t i o n o f s t y r e n e t o e th y l b e n z e n e a s a t e s t r e a c t i o n ,
i t was
found t h a t th e t o t a l l i q u i d volume had a c o n s i d e r a b l e i n f l u e n c e on t h e o b s e rv e d r e a c t i o n v e l o c i t y .
The t o t a l volume
o f l i q u i d may c o n s i s t o f s t y r e n e a lo n e o r s t y r e n e p l u s a s o l v e n t s u c h a s an a l c o h o l , k e to n e o r h y d r o c a rb o n . p o s s i b i l i t i e s were n o t i n v e s t i g a t e d .
A ll s o lv e n t
W ith a b o u t t h e same
am ount o f c a t a l y s t b e i n g u s e d f o r e a c h r u n , and u s i n g a c o n s t a n t s h a k in g f r e q u e n c y , th e r a t e i n c r e a s e s a t f i r s t w i t h l i q u i d volume even th o u g h t h e r a t i o o f c a t a l y s t to h y d ro g e n
il
accep to r is decreased.
3.
A d kin s^ h a s i n d i c a t e d t h a t th e r a t e o f
A d k in s, " R e a c t i o n s o f Hydrogen w i t h O rg an ic Compounds", U n i v e r s i t y of W isc o n sin P r e s s , M adison, W is c o n s in , 1937, p . 9.
h y d r o g e n a t i o n o v e r a c a t a l y s t may v a r y w i t h t h e amount and k i n d o f s o l v e n t a l t h o u g h he d o es n o t s t a t e s p e c i f i c a l l y t h a t t o t a l l i q u i d volume i s a f a c t o r . I t was a l s o fo u nd t h a t t h e h y d r o g e n a t i o n v e l o c i t y of s t y r e n e was n o t a lw a y s p r o p o r t i o n a l to t h e am ount o f c a t a l y s t used.
Thus, u s i n g tw ic e t h e amount o f c a t a l y s t d i d n o t d o u b le
th e r e a c t i o n r a t e .
T his n o n - p r o p o r t i o n a l i t y o f th e amount
o f c a t a l y s t to t h e m easu red h y d r o g e n a t i o n v e l o c i t y h a s b e e n o b s e r v e d i n o t h e r h y d r o g e n a t i o n r e a c t i o n s and w i t h o t h e r h y d r o g en atio n c a t a l y s ts ^ .
4.
F en sk e i n G r o g g in s , " U n i t P r o c e s s e s i n O rg anic O h e m is tr y " , p . 525, M cGraw-Hill Book G o ., I n c . ( 1 9 4 7 ) . I t i s t h e p u r p o s e o f t h i s p a p e r t o show t h a t t h e l i q u i d
volume may be f a c t o r i n th e l i q u i d p h a s e h y d r o g e n a ti o n o f s t y rene, is,
t h a t t h i s f a c t o r d o es n o t depend on s o l v e n t p r o p e r t y and
t h e r e f o r e , q u i t e d i s t i n c t from th e s o - c a l l e d s o l v e n t e f
f e c t or f a c to r .
I t i s p o s s i b l e t h a t th e n o n - p r o p o r t i o n a l i t y
o f t h e amount o f c a t a l y s t to t h e r a t e and th e l i q u i d volume e f f e c t a r e i n t e r r e l a t e d phencmena. E x p e r im e n ta l M a t e r i a l s . - Raney n i c k e l a l l o y (5 0 ^ M ) was f u r n i s h e d
ill
by t h e Harshaw Ohemioal Company, C l e v e l a n d , O h io .
The W-4
Raney n i c k e l was p r e p a r e d a c c o r d i n g to th e p r o c e d u r e g iv e n by P a v l i c and A d k in s ^ .
6.
P a v l i c and A d k in s, J . M . Chem. S oc. . 6 8 , 1 4 7 1 ( 1 9 4 6 ). L in d e ta n k h y d ro g e n was u s e d w i t h o u t f u r t h e r p u r i f i c a t i o n . The s t y r e n e was from Eastm an Kodak C o ., w h i te l a b e l g r a d e , b e i n g 1 .5 4 3 3 .
I n th e b e g i n n i n g th e i n h i b i t o r was removed
by w ash in g w i t h d i l u t e a l k a l i s o l u t i o n .
S ty re n e w i t h o u t
i n h i b i t o r , how ever, had to be f r e s h l y d i s t i l l e d b e f o r e u s e . I t was soon fo u n d t h a t th e same r e s u l t s w ere o b t a i n e d w i t h s t y r e n e c o n t a i n i n g th e i n h i b i t o r a s w i t h f r e s h l y d i s t i l l e d u n s t a b i l i z e d s t y r e n e so t h a t the t r e a t m e n t to remove th e i n h i b i t o r was ab an d o n ed . Com m ercial a b s o l u t e e t h a n o l was r e f l u x e d w i t h some Raney n i c k e l c a t a l y s t f o r a b o u t a n h o u r and th e n d i s t i l l e d
(n^® = 1 .6 0 1 )
S t y r e n e i s p r a c t i c a l l y q u a n t i t a t i v e l y c o n v e r t e d to e t h y l b e n z e n e ( b . p . 1 3 4 , 5 - 1 3 4 . 8 ^ , u n c o r r e c t e d , n ^^ = 1 . 4 9 3 0 ) . Amounts from 50 th r o u g h 75 m l. o f a l i q u i d m ix t u r e o f s t y r e n e , i n e t h a n o l i n 1 :2 p a r t s by volum e, h y d r o g e n a te d o v e r d i f f e r e n t w e ig h t s o f c a t a l y s t ( 0 .0 9 4 g . t o 0 .4 9 0 g . ) a t r a t e s r a n g in g from 0 . 4 5 p s i . / m i n . t o 2 .3 0 p s i . / m i n . , y i e l d e d e s s e n t i a l l y th e same p r o d u c t a s i n d i c a t e d by th e f o l l o w i n g s e r ie s of r e f r a c tiv e in d ic e s:
n§^, 1 .4 0 7 0 , 1 .4 0 6 9 , 1 .4 0 7 9 ,
1 .4 0 7 0 , 1 .4 0 7 0 . The c a t a l y s t was m easured o u t w i t h a s m a ll g l a s s s p o o n .
Iv
By a r o u t i n e s y ste m o f f i l l i n g th e spoon w i th t h e w e t c a t a l y s t , l e v e l i n g by s c r a p i n g a c r o s s t h e to p o f th e spoon w i t h a m e t a l s p a t u l a , f a i r l y e q u a l am ounts o f c a t a l y s t can be m e a s u re d . Three s u c c e s s i v e m easu rem ents o f c a t a l y s t c h e c k e d by w e ig h in g on an a n a l y t i c a l b a l a n c e w ere fo u n d t o b e , to t h e c l o s e s t m i l l i g r a m , 0 .4 8 3 g . , 0 .4 8 6 g . and 0 .4 9 0 g .
W eig h in g s o f two
l e v e l s p o o n s f u l o f a n o t h e r c a t a l y s t p r e p a r a t i o n were 1 .1 6 g . , 1 .1 5 g . an d 1 .1 4 g .
These w e i g h t s a r e a s c l o s e a s a r e n e e d e d
f o r t h e e x p e r im e n t s s i n c e th e r a t e s a r e e x p r e s s e d t o th e n e a r e s t 0 .0 5 p s i . / m i n . A p p a r a tu s and P r o c e d u r e . - The h y d r o g e n a t i o n s w ere c a r r i e d o u t i n a 375 m l. h e a v y - w a ll e d , g l a s s - r e a c t i o n b o t t l e a t t a c h e d to a s t a n d a r d P a r r l o w - p r e s s u r e s h a k in g a p p a r a t u s w i t h a m e t a l t a n k o f a b o u t 4 . 1 1 . c ^ -p a c ity .
The m oto r i s r a t e d a t 1725
r p m ., w hich i s re d u c e d to a b o u t l / 7 so t h a t th e f l a s k i s sh ak en a t a b o u t 250 o s c i l l a t i o n s p e r m in u te .
A Dry I c e - a c e t o n e
c o o le d m e ta l t r a p i s p l a c e d b etw een th e h y d ro g en t a n k on th e a p p a r a t u s and th e r e a c t i o n b o t t l e . The m a t e r i a l to be h y d r o g e n a te d , s o l v e n t ,
i f a n y , and
c a t a l y s t a r e i n t r o d u c e d i n t o th e r e a c t i o n b o t t l e , w hich i s th e n a t t a c h e d t o t h e a p p a r a t u s .
The f l a s k i s a l t e r n a t e l y
e v a c u a t e d and f i l l e d w i t h hydrog en t h r e e ti m e s .
The i n i t i a l
p r e s s u r e i s a d j u s t e d to 4 6 .0 p s i . gauge p r e s s u r e o f h y d ro g e n and t h e s h a k in g s t a r t e d a t room t e m p e r a t u r e a f t e r l a p s e of an a r b i t r a r i l y s t a n d a r d i z e d p e r i o d o f tim e t h e c a t a l y s t h a s b een i n c o n t a c t w i t h t h e s t y r e n e . m ost r u n s .
T h is was 11 m in u te s f o r
P r e s s u r e was e s t i m a t e d to 0 .0 1 p s i .
on th e
B ourdon gauge a t t a c h e d t o th e t a n k . m e n is c u s r e a d e r .
R e a d in g s w ere made w i t h a
I n a d d i t i o n t o p r o v i d i n g an e n l a r g e d v ie w
o f t h e gauge s c a l e ,
i t i n s u r e s r e a d i n g s a t r i g h t a n g l e s to
th e fa c e of th e gauge.
The c o u r s e of t h e r e a c t i o n was f o l
low ed by th e d ro p i n h y d ro g en p r e s s u r e . The s lo p e o f th e s t r a i g h t l i n e p o r t i o n o f th e h y d r o g e n consumed tim e c u rv e was u s e d a s th e m easure of c a t a l y t i c a c tiv ity .
T his i s a more r e p r o d u c i b l e m easure t h a n t h e tim e
r e q u i r e d f o r c o m p le tio n o f th e r e a c t i o n . R e s u l t s an d D i s c u s s i o n The change i n h y d r o g e n a t i o n r a t e o f s t y r e n e w i t h volume i s i l l u s t r a t e d in F ig . 1.
The e f f e c t o f i n c r e a s i n g am ounts o f
e t h a n o l and o f e t h y l b e n z e n e on th e h y d r o g e n a t i o n r a t e o f 25 m l. o f s t y r e n e i s shown i n F i g s . 1 and E, r e s p e c t i v e l y .
The
r e a c t i o n v e l o c i t y i n c r e a s e i n t h e s e c a s e s o v e r t h a t of 25 m l. o f s t y r e n e h y d r o g e n a te d w i t h o u t add ed s o l v e n t c a n n o t be w h o lly a t t r i b u t e d to a s o - c a l l e d s o l v e n t e f f e c t o r f a c t o r i n v iew o f th e r e s u l t s o b t a i n e d w i t h s t y r e n e a l o n e .
P a r t o f th e
i n c r e a s e i s p r o b a b ly due to t h e i n c r e a s e i n t o t a l l i q u i d v o lu m e. The change i n r a t e w i t h volume a p p a r e n t l y d e p e n d s on th e a c t i v i t y o f th e c a t a l y s t .
I n F i g . 3, t h e r a t e s o f h y d r o
g e n a t i o n o f d i f f e r e n t am ounts o f a s t y r e n e - e t h a n o l s o l u t i o n ( 1 : 2 p a r t s by volume) a r e p l o t t e d a g a i n s t th e t o t a l l i q u i d volum e.
The d i f f e r e n t c u r v e s w ere o b t a i n e d w i t h t h e same
c a ta ly s t but a t d if f e r e n t ages.
I t i s seen t h a t a s th e
c a t a l y s t d e c r e a s e s i n a c t i v i t y due t o a g i n g , th e c h a n g e s i n
VI
P ig . 1
The E f f e c t o f L iq u id Volume on the H ydrogenation R ate o f S ty ren e
2.00
II
RATE
EjUb. m in. 1 .5 0
1.00
0 .5 0 25
50
75
100
125
TOTAL VOLUME — m l. I II
S ty ren e e à ly • 25 m l. o f e ty r e n e p lu s added e th a n o l
v il
F ig .2
The E f f e c t o f E th y lb e n z e n e on t h e H y d ro g e n a tio n R a te o f S t y r e n e
3 .0 0
RATE min
2.50
2 .0 0 25
50
75
100
125
Volume o f E th y lb e n z e n e Added t o 2 5 m l. of S t y r e n e — m l.
v iii
F ig .5
E f f e c t o f Age on C a t a l y s t
R ate P >8 » 1 ♦
m in. 2.00
1 .5 0
1.00
50
75 T o t a l volume — ml.
I Age o f C a t a l y s t , one week, I I Four weeks I I I Four months
100
Ix
r a t e w i t h volume d e o r e a s a s u n t i l f i n a l l y t h e volume e f f e c t seem s to d i s a p p e a r .
T h is i s i l l u s t r a t e d i n Curve I I I , F i g . 3 ,
w i t h t h e c a t a l y s t a t th e age o f f o u r m o n th s.
T h is i s an
i m p o r t a n t r e s u l t b e c a u s e i t shows t h a t th e l i q u i d volume e f f e c t i s n o t d e t e r m in e d s o l e l y by e x t e r n a l p h y s i c a l f a c t o r s su c h a s t h e volume o f l i q u i d , s i z e an d shape o f th e r e a c t i o n f l a s k , s h a k in g f r e q u e n c y , and th e am ount o f c a t a l y s t , b u t a l s o by an i n t r i n s i c c h a r a c t e r i s t i c o f one o f t h e r e a c t a n t s , n am ely , t h e a c t i v i t y o f t h e c a t a l y s t . The r a t e o f h y d r o g e n a ti o n o f s t y r e n e i s n o t p r o p o r t i o n a l to th e am ount o f t h e c a t a l y s t u s e d .
T h is i s i l l u s t r a t e d in
F i g s . 4 and 6 where t h e u p p e r c u r v e s were o b t a i n e d w i t h em ploy m ent o f a b o u t tw ic e a s much c a t a l y s t a s u s e d f o r th e lo w e r curve.
I t s h o u ld b e o b s e rv e d , e s p e c i a l l y i n F i g . 4, t h a t
to w ard s th e lo w e r v olu m es t h e r a t e becomes l e s s s e n s i t i v e t o ch an g es i n t h e amount o f c a t a l y s t and e r r o r s i n m e a s u rin g t h e q u a n t i t y o f c a t a l y s t becomes l e s s i m p o r t a n t .
I t i s a lso
a p p a r e n t from t h e g r a p h s t h a t th e same c a t a l y s t to h y d ro g en a c c e p t o r r a t i o may n o t g iv e t h e same h y d r o g e n a t i o n r a t e . I n F i g . 6 , a c o m p a riso n o f two c a t a l y s t b a t c h e s o f d i f f e r e n t age i s made i n th e h y d r o g e n a ti o n o f 25 m l. o f s t y r e n e i n v a r i o u s am o un ts o f e t h a n o l .
R e la tiv e a c t i v i t i e s are b e t t e r
shown i n t h e m anner i l l u s t r a t e d , by h y d r o g e n a t i o n s c a r r i e d o u t a t d i f f e r e n t l i q u i d v o lu m es.
The more a c t i v e c a t a l y s t
i s i n d i c a t e d n o t only by a h i g h e r h y d r o g e n a t io n v e l o c i t y , b u t a l s o by a s t e e p e r r a te - v o lu m e s lo p e on th e a c e n d in g p o r t i o n o f th e c u r v e .
T his i s a l s o i l l u s t r a t e d by t h e example on
F ig .4
S f f e c t o f th e Amount o f C a t a l y s t on th e H y d ro g e n a tio n R ate
2 .5 0 R a te 2.00 p .8 .1 . m in.
1.00
100
125
Volume o f S t y r e n e — m l. Upper c u rv e o b t a i n e d w i th tw ic e th e amount o f c a t a l y s t u s e d f o r t h e lo w e r c u r v e .
XI
F ig . 5
E f f e c t o f th e Amount o f C a t a l y s t on t h e H y d r o g e n a tio n R ate
R ate 3.00 p .a .i. m in . II
2.00
1.00 50
75
100
125
T o t a l Volume - - m l. L i q u i d m ix tu re o f s t v r e n e and e t h a n o l i n 1 :2 p a r t s by volum e. Upper c u rv e o b t a i n e d w i th tw ic e th e amount o f c a t a l y s t u sed f o r th e lo w e r c u r v e .
x ii
F ig . 6
Comparison o f Two Raney N ic k e l P r ep a ra tio n s
2 .0 0 RATE
P.s.i. min.
I C a t a ly s t N 1(R )1-73 I I C a ta ly s t N i(R )2 -1 0
1 .5 0
25
50
75
Volume o f Ethanol Added to 25 m l. o f S tyren e — m i l l i t e r s
100
x iii
t h e d e c l i n e o f c a t a l y t i c a c t i v i t y due t o a g i n g w here a c o n s t a n t c o m p o s itio n l i q u i d m i x tu r e i s h y d r o g e n a te d . B e c a u se some u n s a t u r a t e d compounds may show s i m i l a r r a t e ch an g es w i t h volume and some may n o t , i t may he s a i d a l s o t h a t p r o p e r c o n c l u s i o n s a b o u t th e r e l a t i v e e a s e o r d i f f i c u l t y o f h y d r o g e n a t io n o f d i f f e r e n t u n s a t u r a t e d compounds o r c l a s s e s o f u n s a t u r a t e d compounds c a n n o t be a d e q u a t e l y made on th e b a s i s o f s i n g l e h y d r o g e n a t i o n r u n s on a r b i t r a r i l y s e t am ounts o f c a t a l y s t , h y d ro g en a c c e p t o r and s o lv e n t® .
6.
The v a l i d i t y o f
O s u ro s , 2eo h and Geczy, Hung:. A c ta . O him ., 1, 1 -2 3 ( 1 9 4 6 ); O.A. 41, 109. . -
t h e c o n c l u s i o n s may be r e s t r i c t e d t o th e n arro w l i m i t s o f th e am ounts s e t f o r th e r u n an d may n o t p r e s e n t th e o v e r a l l p ic tu re . Acknowledgment. - The a u t h o r s a r e I n d e b te d to t h e Harshaw C hem ical Company f o r f i n a n c i a l s u p p o r t o f t h i s s tu d y . Summary 1.
The r a t e o f l i q u i d ph ase h y d r o g e n a t io n o f s t y r e n e o v e r
f r e s h l y p r e p a r e d Raney n i c k e l c a t a l y s t I s I n f l u e n c e d by th e t o t a l l i q u i d volum e.
The t o t a l l i q u i d volume may b e s t y r e n e
alo n e o r s ty r e n e p lu s a s o lv e n t.
T h is f a c t o r I s q u i t e d i s t i n c t
from s o m e th in g w hich dep en d s on s o l v e n t p r o p e r t y . 2.
W ith th e d e c l i n e I n c a t a l y t i c a c t i v i t y due t o a g e , th e
l i q u i d volume e f f e c t d i s a p p e a r s .
x lv
(OOlTRIBUTIOir FROM TES RSPARTtîSrT OF OHEtaSTEY AITD THB PERDUS RESEARCH POUITDATIOIT, PERDUS UlTITERSITY) s o m PAOTORS liTPLUBICIlTG IBS ACTIVITY OF EAÎIEY ÎÎICKBL CATALYST PART I I TH3 EFFECT OF LIQ.UID VOLUl'iDS AITD THE AIAOUlTT OF CATALYST OH TEE RATS OF LIQUID PHASE HYDRCG'YATIO'-l by Y. Yamada w i t h Ed. F . D e g e rln g ^ AH ABSTRACT
1.
A b s t r a c t e d from a t h e s i s s u b m itte d to th e f a c u l t y o f Purdue U n i v e r s i t y by Y. Yamada i n p a r t i a l f u l f i l l m e n t o f th e r e q u i r e m e n t s f o r th e d e g re e o f D o c to r o f P h i l o s o p h y , F e b r u a r y , 1950.
2.
P r e s e n t a d d r e s s : Armour R e s e a r c h F o u n d a tio n of I l l i n o i s I n s t i t u t e o f Technology, C h icag o , 111. I t was shown p r e v i o u s l y t h a t t h e h y d r o g e n a t i o n
v e lo c ity
o f s t y r e n e o v e r f r e s h l y p r e p a r e d Raney n i c k e l v a r i e s w i th th e t o t a l l i q u i d volume and a l s o t h a t th e v e l o c i t y change w i t h th e amount o f c a t a l y s t was n o t p r o p o r t i o n a l to th e change I n th e w e ig h t o f c a t a l y s t em ployed. S e v e r a l I n v e s t i g a t o r s have s t u d i e d th e I n f l u e n c e o f a g i t a t i o n ^ on h y d r o g e n a t i o n r a t e and found t h a t f o r c e r t a i n
3.
a . B lo v lo h and h'habrova, J . P h y s. Chem. ( U .S .S .R .) 19. 2 39-49 (1 9 4 5 ); O .A ., b . G o l * d a n s k ll and S l o v l c h . J . P h y s. Chem. ( U .S .S .R .) 20, 1085-93 ( 1 9 4 6 ); G .A ., 4 l T ^ 7 3 :
XV
0
.
Max t e cl i n "Handbuch d e r K a t a l y s e " , S p r i n g e r - V e r l e g , V ien n a, 1943, V o l. 7, P a r t 1, p . 626.
r e a c t i o n s an I n c r e a s e In t h e s h a k in g f re q u e n c y i n c r e a s e s the h y d r o g e n a ti o n v e l o c i t y up t o a maximum a f t e r w hich f u r t h e r i n c r e a s e i n s h a k in g d o e s n o t I n c r e a s e t h e o b s e rv e d r e a c t i o n ra te . To e x p l a i n the o b s e rv e d h y d r o g e n a ti o n - ^ o c i t y change w i t h l i q u i d volume and w i t h th e amount o f c a t a l y s t , a m odel I s p r o p o s e d , w hich i s b a s e d on a p o s s i b l e r e l a t i o n s h i p among th e f o l l o w i n g c o n t r o l l a b l e f a c t o r s :
th e f r e q u e n c y o f
s h a k in g , the l i q u i d volum e, th e a c t i v i t y , and th e amount o f c a ta ly s t.
H y d ro g e n a tio n v e l o c i t i e s o f s t y r e n e w i t h c h a n g e s
i n th e amount o f c a t a l y s t and In the volume o f l i q u i d h av e b een s u c c e s s f u l l y p r e d i c t e d in t h e few c a s e s i n v e s t i g a t e d . P rin c ip le s L i q u i d volum e. - Inasm uch a s t h e hydrogen a t Ion r a t e g o es up a t f i r s t TiTlth l i q u i d volum e, o t h e r f a c t o r s b e i n g e q u a l , i t seems r e a s o n a b l e t o su pp ose t h a t an optimum d i s p e r s i o n o f th e c a t a l y s t p a r t i c l e s a n d , t h e r e f o r e , maximum c a t a l y t i c s u r f a c e e x p o s u r e . I s n o t r e a l i z e d a t th e s m a l l e r volum es and t h a t th e e f f e c t o f i n c r e a s i n g t h e amount of l i q u i d I s t o In c re a s e th e d is p e r s io n o f th e c a t a l y s t .
S in c e th e s o l i d
c a t a l y s t p a r t i c l e I s s u rr o u n d e d by l i q u i d a t a l l t i m e s , th e d i s p e r s i o n o f th e c a t a l y s t s h o u ld n o t have much e f f e c t on th e s ty r e n e .
On th e o t h e r hand, th e p r o c e s s e s and r e a c t i o n
t a k i n g p l a c e on t h e s u r f a c e may be f a s t enough t h a t th e E x t e n t o f s u r f a c e a r e a exp osed to d i r e c t hydro gen bombardment
xvi
may c o n o e iv a b ly become r a t e d e t e r m i n i n g .
T h is p i c t u r e
r e q u i r e s th e co n cep t o f c a t a l y s t p a r t i c l e s b lo c k in g each o th e r a g a i n s t d i r e c t hyd ro g en bom bardment, t h i s e f f e c t b e in g re d u c e d a s th e l i q u i d volume i s i n c r e a s e d and t h u s s e p a r a t i n g th e p a rtic le s, G rol* d an sk ii^ h a s i n d i c a t e d a r e l a t i o n s h i p b etw een th e
4.
GrOl*danskii, Z h u r. F i z . Khim. ( J , P h y s. Ghem. ) 22, 137480 ( 1 9 4 8 ); 0 . 1 7 ^ , 2498.
i n t e r f a o i a l a r e a o f th e g a s - l i q u i d p h a s e s and r e a c t i o n r a t e fo r c e rta in re a c tio n s.
S in c e s t y r e n e can be k e p t f o r a co n
s i d e r a b l e l e n g t h o f tim e u n d e r hydrog en w i t h o u t a p p r e c i a b l e d ro p i n h y d ro g en p r e s s u r e , even i n t h e p r e s e n c e o f Raney n i c k e l i f t h e r e i s no a g i t a t i o n , i t seems l i k e l y t h a t t h e r e a c t i o n t a k e s p l a c e m o s tly on t h e c a t a l y s t s u r f a c e a t o r n e a r th e g a s-liq u id in te rfa c e .
F o r a f i x e d shape and s i z e of r e a c t i o n
f l a s k and a c o n s t a n t s h a k in g f r e q u e n c y , th e i n t e r f a c i a l a r e a may
be d e te r m in e d t o some e x t e n t by A co u n te ra c tin g
e f f e c t , a s th e
th e l i q u i d volum e. l i q u i d volume i n c r e a s e s ,
i s t h a t more and more c a t a l y s t p a r t i c l e s w i l l be fo u n d i n th e body o f th e l i q u i d and away from t h e i n t e r f a c e . S h ak in g f r e q u e n c y . - I n c r e a s e i n s h a k in g f r e q u e n c y t e n d s to in c re a se th e g a s -liq u id in te r f a c e .
The n e t e f f e c t o f
i n c r e a s i n g t h e e x t e n t o f i n t e r f a c i a l a r e a f o r a g iv e n volume o f l i q u i d i s to have
more p a r t i c l e s
W hile a g i t a t i o n
may be s a i d t o
a t th e i n t e r f a c e . a i d th e s o l u t i o n ofh y d ro
gen i n th e l i q u i d (some i n v e s t i g a t o r s have m e n tio n e d th e
x v iî
n e o e œ ity o f k e e p in g t h e l i q u i d s a t u r a t e d w i t h h y d r o g e n ), i t s h o u ld h e p o i n t e d o u t t h a t so f a r no r e l a t i o n s h i p h a s b e e n fo u n d b etw een t h e s o l u b i l i t y o f h y d rog en i n a s o l v e n t a n d t h e o b s e r v e d r a t e o f r e a c t i o n i n t h e s o lv e n t® .
5.
M axted and Moon, J . Qhem. S oc. . 19 38 , 4 5 4 -5 . I f a b l o c k i n g e f f e c t a s m e n tio n e d u n d e r l i q u i d volume
above i s p o s t u l a t e d , th e n th e p e r i o d o f p a r t i c l e o s c i l l a t i o n becomes i m p o r t a n t .
T h is may be p i c t u r e d a s th e tim e n e c e s s a r y
f o r a p o i n t , on th e c a t a l y s t s u r f a c e , to move from one d i r e c t i o n to th e o p p o s i t e by r o t a t i o n o f th e p a r t i c l e a t some a v e ra g e frequency (see F ig . l a ) .
The p e r i o d o f p a r t i c l e o s c i l l a t i o n
d e t e r m in e s th e r a t e a t w hich a b l o c k e d c a t a l y s t s u r f a c e moves o u t i n t o an e x p o sed p o s i t i o n . A c t i v i t y o f t h e c a t a l y s t . - A c a t a l y t i c c y c l e i s composed o f t h e v a r i o u s p h a s e s in v o lv e d i n h e t e r o g e n e o u s c a t a l y s i s ; t h e d i f f u s i o n o f th e r e a c t a n t s to t h e c a t a l y s t s u r f a c e , a d s o r p t i o n , r e a c t i o n p r o p e r on th e s u r f a c e , d e s o r p t i o n , an d d i f f u s i o n o f t h e p r o d u c t away fro m th e s u r f a c e .
The g r e a t e r
t h e s p e e d o f th e v a r i o u s p h a s e s th e s h o r t e r t h e tim e r e q u i r e d to go th ro u g h t h i s c a t a l y t i c c y c l e .
What i s m eant by th e
a c t i v i t y o f a c a t a l y s t dep en ds on th e f r e q u e n c y o f t h i s cy cle® .
6.
P a u l , B u l l . 8 0 0 . chim . ( 5 ) , 7, 296-545 (1 9 4 0 ). S in c e th e hydrogen i s i n th e g a s p h a se and t h e s t y r e n e .
x v iii
i n th e l i q u i d p h a s e , f o r p u rp o s e o f d i s c u s s i o n th e d i f f u s i o n o f th e hy dro gen m o le c u le to t h e c a t a l y s t s u r f a c e h a s b een s e p a r a t e d from th e a d s o r p t i o n o f th e h y d ro g e n , th e d i f f u s i o n and a d s o r p t i o n o f th e s t y r e n e on t h e c a t a l y s t s u r f a c e These l a s t t h r e e p h a s e s have b een lumped t o g e t h e r w i t h t h e s u b s e q u e n t s t e p s l i s t e d above and th e whole t h i n g r e f e r r e d t o a s s u r f a c e p r o c e s s e s and r e a c t i o n . F o r a f a s t r e a c t i o n where d i f f u s i o n i n t o th e c a t a l y s t i s s lo w e r th a n t h e r e a c t i o n p r o p e r on the s u r f a c e , may be l a r g e l y l i m i t e d to th e o u t e r s u r f a c e .
th e r e a c t i o n
The d e p th to
w hich th e r e a c t i o n w i l l p e n e t r a t e i s th e n a f u n c t i o n o f t h e r e a c t i o n v e l o c i t y w h ich i n t u r n depends on c a t a l y t i c a c t i v i t y . A ssu m p tio n s made i n d e v e lo p in g a w o rk in g model o f th e h y d r o g e n a t i o n o f s t y r e n e over Raney n i c k e l c a t a l y s t ,
i n w h ich
th e c a t a l y s t p a r t i c l e s a r e t r e a t e d a s s o l i d s p h e r e s o f u n ifo rm s i z e ( o b v io u s l y an o v e r - s i m p l i c a t i o n ) , a r e : 1.
The r e a c t i o n t a k e s p l a c e on th e c a ta ly s t s u r f a c e .
2.
The s u r f a c e p r o c e s s e s and r e a c t i o n a r e so f a s t t h a t any hydrogen m o le c u le which i s g o in g to r e a c t does so i n s t a n t l y upon c o l l i d i n g w i t h th e c a t s l y s t s u r f a c e , a l t h o u g h each c o l l i s i o n o f a hydrogen m o le c u le w i t h th e c a t a l y s t i s n o t g o in g to p ro d u c e a re a c tio n .
The a c t i v e c e n t e r s in v o lv e d a t th e
p o i n t o f c o l l i s i o n m ust have gone th ro u g h a c a t a l y t i c c y c l e and be re a d y f o r th e n e x t r e a c t i o n . 3.
The p e r i o d of p a r t i c l e o s c i l l a t i o n i s lo n g r e l a t i v e to t h e p e r i o d o f c a t a l y t i c c y c le i n w hich a p a r t i c l e
x ix
may be c o n s i d e r e d to have b e e n p r a c t i c a l l y s t a t i c r e l a t i v e to th e o t h e r p a r t i c l e s d u r in g t h e p e r i o d of a c a ta ly tic c y c le . 4.
When two o r more p a r t i c l e s a r e c l o s e t o g e t h e r , e a c h c a n n o t f u l l y exp ose i t s t o t a l s u r f a c e a r e a t o d i r e c t h y d rog en bombardment b e c a u s e p a r t o f i t i s b l o c k e d by t h e o t h e r s .
5.
The m e a su re d r a t e o f h y d r o g e n a t i o n i s p r o p o r t i o n a l to t h e e f f e c t i v e c a t a l y t i c s u r f a c e a r e a and n o t to th e t o t a l c a t a l y t i c su rfa c e a r e a . These te rm s r e q u i r e d e f i n i t i o n . f a s t s u r f a c e p r o c e s s and r e a c t i o n ,
By assum ing a
th e c a t a l y t i c
p r o c e s s i s l a r g e l y l i m i t e d to th e o u t e r s u r f a c e . The t o t a l c a t a l y t i c s u r f a c e r e f e r s to t h e o u t e r s u r f a c e i n v o l v e d i n th e r e a c t i o n and n o t to th e a c t u a l t o t a l , b o t h i n n e r and o u t e r , s u r f a c e a r e a s . The e f f e c t i v e c a t a l y t i c s u r f a c e a r e a i s th e a r e a ex p o sed to d i r e c t hydrogen bom bardment.
The
t o t a l su rfa c e a r e a in c lu d e s t h i s a re a as w e ll as t h e a r e a w h ich i s o b s t r u c t e d in p a r t from d i r e c t h y d rog en bom bardm ent. 6.
T h e re i s a c e r t a i n optimum r a t i o o f c a t a l y t i c w e ig h t t o l i q u i d volum e, i . e . ,
one p a r t i c l e o f
c a t a l y s t p e r u n i t volum e, a t w hich th e h y d r o g e n a tio n r a t e i s maximum.
At t h i s r a t i o ,
th e e f f e c t i v e
s u r f a c e a r e a and t h e t o t a l s u r f a c e a r e a o f th e c a t a l y s t c o in c id e .
I n o t h e r w o rd s, o b s t r u c t i o n by
XX
o th e r p a r tic le s i s n i l .
T h is means t h a t when
th e amount o f c a t a l y s t i s d o u b le d ,
th e volume a t
w h ic h th e maximum r a t e o c c u r s i s a l s o d o u b le d . The e f f e c t i v e s u r f a c e a r e a e x i s t s o n ly u n d e r c o n d i t i o n s o f e x p erim en t.
I t i s p r o b a b l y b e s t e x p r e s s e d i n te rm s o f c o
o r d i n a t e s s i n c e by t h i s t r e a t m e n t , i t i s p o s s i b l e to t a l k a b o u t s u r f a c e w i t h o u t any s p e c i f i c s t a t e m e n t a b o u t t h e a c t u a l su rface a re a .
L e t t h e c e n t e r o f th e c a t a l y s t s p h e r e be t h e
o r i g i n o f t h e t h r e e c o o r d i n a t e s , x , y and z, w i t h t h e s i x p r o j e c t i o n s , i x , ±y and i s , r e p r e s e n t i n g th e t o t a l s u r f a c e area.
A t th e optimum volume f o r a g iv e n amount o f c a t a l y s t ,
t h e e f f e c t i v e s u r f a c e a r e a e q u a l s th e t o t a l s u r f a c e a r e a an d i s r e p r e s e n t e d by a l l th e s i x p r o j e c t i o n s o f e x p o s u re ( f i g . l b ) . A r e p r e s e n t a t i o n o f t h e c o n d i t i o n o f optimum r a t i o of c a t a l y s t to l i q u i d volume to g iv e maximum r e a c t i o n r a t e i s giv en in P ig . l b .
I f two p a r t i c l e s now occupy t h e same volume,
r e p r e s e n t i n g th e e q u i v a l e n t o f d o u b l in g th e amount of c a t a ly st,
e a c h p a r t i c l e c o n t r i b u t e s o n ly 5 /6 o f i t s s u r f a c e a r e a
s i n c e l / 6 o f i t i s b l o c k e d by t h e o t h e r . face,
The e f f e c t i v e s u r
t h e r e f o r e , i n c r e a s e s o n ly Z x 5 /6 o r 5 /3 t i m e s t h a t o f
t h e o r i g i n a l am ount.
By t r i p l i n g th e amount o f c a t a l y s t ,
th e
e f f e c t i v e a r e a g o e s up 7 / 3 tim e s i n s t e a d o f t h r e e t i m e s , s i n c e o f t h e t h r e e p a r t i c l e s i n t h e u n i t volum e, one i s b l o c k e d on two s i d e s , w h ile e a c h o f th e o t h e r two i s b lo c k e d on one s i d e . As t h e number o f p a r t i c l e s p e r u n i t volume o f l i q u i d i n c r e a s e s , th e p o s s i b l e c o m b in a tio n o f c a t a l y s t p o s i t i o n s
xxi
F ig , 1
R e l a t i v e S u r f a c e E x po sure Based on S p h e r i c a l p a rtic le s •fZ
4X Y a . P e rio d of P a r t i c l e O sc illa tio n
b#
S ix p r o je c tio n s to d e s ig n a te f u l l o u te r s u r f a c e a r e a ex p o su re
c.
b . One p a r t i c l e p e r u n i t volume t o g iv e f u l l s u r f a c e e x p o s u re a n d , t h e r e f o r e , maximum r a t e . c . Two p a r t i c l e s p e r u n i t v olu m e. d , e . Three p a r t i c l e s p e r u n it v o lu m e.
z x il
in c re a s e s .
The a v e r a g e i n c r e a s e i n e f f e c t i v e s u r f a c e a r e a
w i l l be fo u n d to b e c l o s e t o th e f i g u r e c a l c u l a t e d by co n s id e r in g th e c a t a l y s t p a r t i c l e s arran g ed in a s t r a i g h t l i n e . The f o l l o w i n g t a b l e g i v e s th e i n c r e a s e i n e f f e c t i v e a r e a w i t h t h e number o f p a r t i c l e s p e r u n i t volum e: T a b le 1 . The I n c r e a s e i n E f f e c t i v e S u r f a c e i r e a w i t h t h e Uumber o f P a r t i c l e s p e r U n i t Volume Humber o f p a r t i c l e s
1
8 3 4 5 6 7 8 9 10
R e la tiv e e f f e c tiv e su rface area 1
5/3 7 /3 3 ll/s 1 3 /3 5 1 7 /3 1 9 /3 7
I f i n s t e a d o f i n c r e a s i n g th e amount o f c a t a l y s t , th e volume o f t h e l i q u i d i s d e c r e a s e d , s t a r t i n g from the volume w hich i s a t th e optimum f o r th e amount o f c a t a l y s t p r e s e n t , th e e f f e c t i v e s u r f a c e a r e a i s assum ed to d e c r e a s e a c c o r d i n g to th e r e c i p r o c a l s o f th e im p ro p e r f r a c t i o n s g iv e n a b o v e .
x x îll
T a b le 2 . D e c r e a s e i n E f f e c t i v e S u r f a c e A rea ______ w i t h D e c r e a s e i n L i q u i d Volume_________ Volume d e c r e a s e R e la tiv e e f f e c tiv e _________________________________ s u r f a c e a r e a 1
1
il
1 /2
3 /5
1 /5 1 /6 1 /7 1 /8 1 /9 l/lO
3 /1 1 3 /1 3 1 /5 3 /1 7 3 /1 9 1 /7
From t h e t r e n d o f th e f i g u r e s f o r t h e e f f e c t i v e s u r f a c e a r e a s f o r th e c o r r e s p o n d i n g f r a c t i o n s t o w hich th e volume i s r e d u c e d , i t may be s e e n t h a t th e e f f e c t i v e s u r f a c e a r e a , f , can be e x p r e s s e d by th e e m p i r i c a l e q u a t i o n : f = 3 /(1 ♦ 2n), where n i s th e f r a c t i o n t o w hich th e o r i g i n a l optimum volume i s red u ced .
T h is i s a u s e f u l e q u a t i o n .
S in c e th e m easu red h y d r o g e n a t i o n r a t e s a r e assum ed to be p r o p o r t i o n a l t o t h e e f f e c t i v e s u r f a c e a r e a , a c u rv e showing t h e change i n r a t e w i t h l i q u i d volume may be p l o t t e d from th e v a l u e s g iv e n ab ov e.
L e t t i n g R s ta n d f o r th e h y d r o g e n a tio n
r a t e a t volume V w hich i s t h e optimum f o r t h e amount o f c a t a l y s t u s e d , 3 / 5 R i s th e r a t e a t 1/E V, 3 /7 R a t l / 4 V, e tc .
I n o t h e r w o rd s, t h i s i s th e t h e o r e t i c a l curv e showing
th e change i n h y d r o g e n a t i o n r a t e w ith l i q u i d volum e. A c c o rd in g to a s s u m p tio n 6, i f V i s th e optimum volume f o r a c e r t a i n am ount, say one u n i t , o f c a t a l y s t and R, th e c o r r e s p o n d i n g r a t e , t h e n f o r tw ic e th e amount o r two u n i t s of
x x lv
c a t a l y s t , t h e optimum volume i s 2Y and t h e r a t e i s £ 6 /9 R. This l a t t e r f i g u r e i s a r r i v e d a t a s f o l l o w s ; u n i t o f c a t a l y s t th e r a t e i s R. a t V, th e r a t e g o e s up t o 5 /3 R.
a t V f o r one
F o r two u n i t s o f c a t a l y s t T h is, in tu rn ,
i s o n ly
0 / 5 o f th e r a t e a t £V, w h ich a c c o r d i n g l y s h o u ld he 6 /3 X 5 / 3 R o r 2 6 /9 R* F i g . 2.
The r e l a t i o n s h i p i s diagrammed i n
The u p p e r c u rv e shows t h e change i n r a t e w i t h l i q u i d
volume u s in g tw ic e th e amount o f c a t a l y s t a s f o r t h e lo w e r curve. E x p e r i m e n t a l d a t a i s p r e s e n t e d w hich shows t h a t change i n h y d r o g e n a t i o n v e l o c i t y w i t h l i q u i d volume and w i t h th e amount o f c a t a l y s t i s a s g iv e n in F i g . £, w hich was d e r i v e d w i t h o u t any p r i o r r e f e r e n c e to a c t u a l d a t a . E x p e r im e n t a l . - M a t e r i a l s , a p p a r a t u s and p r o c e d u re were d i s c u s s e d i n th e A b s t r a c t , P a r t I , o f t h i s t h e s i s . R e s u l t s and D i s c u s s i o n . - The m easured h y d r o g e n a t i o n v e l o c i t i e s o f s t y r e n e w i t h o u t s o l v e n t f o r th e a s c e n d in g p o r t i o n o f th e r a t e - l i q u i d volume cu rve o v er one l e v e l s p o o n f u l ( c a , 0 . 9 g. m o i s t w e ig h t i n d io x an ) o f a W-4 Raney n ic k e l c a t a l y s t a re as fo llo w s:
Run
S ty r e n e
Rate
90-3
25 m l.
0 .7 5 p s i . / m i n .
9 1-3
50 m l.
1 .1 5 -
92-A
75
1 .5 0
XXV
F ig ,2
T h e o r e t i c a l Curves Showing Change o f R ate w i t h 50< D e c re a s e o r 100^ I n c r e a s e i n th e Amount o f C a t a l y s t
3R R ate
1 0 /9 2R
2 /3 R
5/3 R
L iq u id Volume
xxvi
A g r a p h i s drawn and th e l i n e p r o j e c t e d ( o f . F i g . 3, lo w e r curve).
The p a r t i c u l a r volume on th e c u r v e a t w hich th e r a t e
i s 5 / 5 t i m e s t h a t a t/v o lu m e one h a l f in m ag nitu de i s t h e optimum volume f o r amount o f c a t a l y s t u s e d .
The v a lu e of
1 ,8 0 p s i . / m i n . a t 100 m l. and 1 .1 0 p s i . / m i n . a t 50 m l. a p p r o x im a t e l y h e a r t h i s r e l a t i o n . t h e r e f o r e , 100 m l.
The optimum volume i s ,
F o r tw ic e th e amount o f c a t a l y s t th e
optimum volume w i l l he EGO m l. and t h e c o r r e s p o n d i n g r a t e 2 5 /9
X 1 .8 0 p s i . / m i n . o r 5 .0 0 p s i . / m i n .
The h y d r o g e n a tio n
v e l o c i t y a t a volume w hich i s a f r a c t i o n o f 200 m l. i s o b t a i n e d hy m u l t i p l y i n g th e n u m e r ic a l v a lu e g iv e n f o r th e c o r r e s p o n d i n g e f f e c t i v e s u r f a c e a r e a i n Table 2 by 5 .0 0 p s i . / m i n . The c a l c u l a t e d v a l u e s f o r t h e h y d r o g e n a t i o n o f s t y r e n e ,
o v er
a p p r o x im a te ly 2 x 0 . 9 g. m o i s t w e ig h t o f t h e same c a t a l y s t , a r e p l o t t e d i n F i g . 4 (u p p e r c u rv e ) a s a r e a ls o th e e x p e r i m e n ta l v a l u e s . When t h e optimum volume l i e s f a r beyond t h e e x p e r i m e n ta l r e g i o n , i t i s n o t e a s i l y d e te r m in e d g r a p h i c a l l y . d e te r m in e d by a m ethod o f a p p r o x im a ti o n .
I t may be
The o b s e rv e d
h y d r o g e n a t i o n 'v e lo c itie s o f a s o l u t i o n o f s t y r e n e in e t h a n o l ( 1 :2 p a r t s by volume) o v e r a b o u t 1 .1 5 g. o f Raney n i c k e l c a t a l y s t are a s fo llo w s; Table 4 .
E x p e r im e n ta l H y d ro g e n a tio n R a t e s o f
Volume o f s t y r e n e e th a n o l m ix tu re
C a ta ly st
60 m l. 75 85
1 .1 2 g . 1 .1 5 1 .1 6
R ate 2 .0 5 p s i . / m i n . 2 .5 0 2 .9 0
X X V ll
Fig* 3
C a lc u la te d and E xperim ental H ydrogenation R ates f o r 100% In c r e a se in th e Amount o f C a t a ly s t
2 .5 0
1.00
0.50 O
25
50
75
Volume o f S ty ren e — m l.
\ C a lc u la te d Rate O E xperim ental Rate
100
x x v lil
The m ethod o f a p p r o x i m a ti o n I n v o l v e s th e c a l c u l a t i o n o f t h e p r o d u c t o f a n assum ed optimum volume and t h e c o r r e s p o n d i n g ra te .
I f 85 m l . , f o r ex am ple, w ere one h a l f o f t h e optimum
volum e, t h e r a t e a t t h i s optimum w i l l be 2 .9 p s i . / m i n . x 5 /3 or 4 .8 4 p s i./m in .
The r e c i p r o c a l s o f th e f r a c t i o n s i n
T able 2 a r e u s e d a s f a c t o r s i n c a l c u l a t i n g th e maximum r a t e . The p r o d u c t o f t h e optimum volume and t h e r a t e i s th e n 170 m l. X 4 .8 4 p s i . / m i n .
I f 85 m l. were o n e - t h i r d o f th e
optimum volum e, t h e maximum r a t e f o r t h i s volume i s 2 .9 0 p s i . / m i n . x 7 / 3 o r 6 .6 7 p s i . / m i n . and t h e p r o d u c t o f th e r a t e an d volume i s 6 .7 6 p s i . / m i n . x 255 m l.
By c a r r y i n g o u t
s i m i l a r c a l c u l a t i o n s f o r l a r g e r assum ed optimum volum es and r e p e a t i n g t h i s p r o c e d u r e f o r 2 .5 0 p s i . / m i n . a t 75 m l. th e n u m e r ic a l v a l u e s o f th e p r o d u c t o f r a t e and volume a r e o b t a i n e d f o r T able 5 .
S in c e th e e x p e r im e n t a l r a t e f o r 75 m l.
and 85 m l. l i e on t h e same c u r v e , somewhere a l o n g t h e way, th e p r o d u c t o f t h e assum ed optimum volume and th e c o r r e s p o n d i n g r a t e s h o u ld b e a b o u t e q u a l . T a b le 5.
C a l c u l a t e d P r o d u c ts of Assumed
F r a c t i o n o f assumed optimum volume 1 /6 1 /6 1 /7 1 /8 1 /9
75 m l. ( 2 .6 0 p s i . / m i n . ) 3440 6860 6670 8500 10700
85 m l. (2 .9 0 p s i . / m i n . ) 4530 6410 8610 11200
T h a t 75 m l. i s l / 7 and 85 m l. i s l / 6 o f t h e optimum volume and t h a t 75 m l. i s 1 /8 and 85 m l. i s l / 7 o f th e optimum volume
X X IX
F i g .4
C a lc u la te d and E xperim ental H ydrogenation R ates f o r 50^ D ecrease in th e Amount o f C a ta ly s t
3 .0 0 R ate
min. 2 .5 0
2 .0 0
1 .5 0
1.00 50
75
L iq u id Volume — m l. S ty ren e in e th a n o l (1*2 p a r ts by volum e)
X C a lc u la te d
Rate Rate
O E xperim ental
XXX
g i v e t h e c l o s e s t p a i r s o f th e p r o d u c t .
For th e f i r s t p a i r
t h e optimum volume i s 526 to 510 m l. and f o r th e s e c o n d p a i r , 600 t o 596 m l.
As a f i r s t a p p r o x i m a ti o n i t i s t h u s e s t a b l i s h e d
t h a t t h e optimum volume i s i n t h e r e g i o n 500 m l, t o 600 m l. A c l o s e r a p p r o x i m a t i o n i s 550 m l.
The p r o d u c t o f volume
and r a t e a t d i f f e r e n t assum ed optimum volum es a r e a s f o l l o w s : T a b le 6. Assumed optimum volume
C a l c u l a t e d P r o d u c t s o f Assumed 60 m l. 2 .0 5 p s i./ m i n .
500 m l. 650 600
75 m l. 2 .5 0 p s i . / m i n .
85 m l. 2 .9 0 p s i . / m i n .
6970 7200 8500
6050 7290 8610
6160 7400 8750
The r e c i p r o c a l o f t h e e q u a t i o n f = 5 / ( 1 -* En) i s th e f a c t o r by w hich t h e e x p e r i m e n t a l r a t e i s m u l t i p l i e d to g e t t h e maximum r a t e a t any p a r t i c u l a r volum e.
The p r o d u c t s o b t a i n e d a ssu m in g
550 m l. a s t h e optimum volume have t h e s m a l l e s t p e r c e n t a g e d iffe re n c e s.
W hile th e optimum volume c a n n o t be d e te r m in e d
w i t h p r e c i s i o n by th e m ethod d e s c r i b e d ,
th e v alu e o b ta in e d i s
a d e q u a te f o r o u r p u r p o s e . T aking 550 m l. a s t h e optimum volum e, t h e a v e r a g e maximum r a t e f o r t h i s volume d e te r m in e d from t h e t h r e e e x p e r i m e n t a l r a t e s i s 1 3 .3 p s i . / m i n . i.e .,
1 /2
F o r one h a l f th e amount of c a t a l y s t ,
X 1 . 1 5 g . , th e optimum volume and maximum r a t e a r e
275 m l. and 9 /2 5 x 1 3 .3 p s i . / m i n . o r 4 .8 0 p s i . / m i n . F i g . 4 (lo w e r cu rv e) from t h e s e v a l u e s .
In
i s p l o t t e d a r a t e - l i q u i d volume c u rv e The c u rv e i s i n v e r y good a g re e m e n t w i t h
th e a c t u a l e x p e r i m e n t a l v a l u e s o b t a i n e d by u s in g one h a l f th e
xxxi
F ig .5
D isp lacem en t o f Optimum Volume w ith the R ed u ction in th e Amount o f C a ta ly s t
2 .5 0
2.00 R ate
1.00
II
0.50
0 50
75 L iq u id volume — m l. L iq u id m ixture c o n ta in in g s ty r e n e and e th a n o l in r a t i o o f l i 2 p a r ts by volu m e. Lower curve o b ta in ed w ith ab o u t o n e - f i f t h th e amount o f c a t a l y s t used f o r th e upper cu rv e.
x x x ll
amount o f c a t a l y s t a s was u s e d f o r th e u p p e r The e x p e r i m e n t a l c u r v e s do
curve.
n o t go up t o t h e c a l c u l a t e d
maximum n o r i s t h e r e l a t i v e m a g n itu d e s o f th e amount o f c a t a l y s t and th e c a l c u l a t e d optimum volume s u c h t h a t t h e b l o c k i n g e f f e c t p o s t u l a t e d can e x i s t .
The p o s s i b i l i t y of t h e
i n t e r f a o i a l a r e a b e in g th e r e a l f a c t o r h a s been m e n tio n e d a s a l s o t h e c o m p l i c a t i o n r e s u l t i n g from th e f a c t t h a t w i t h i n c r e a s e i n l i q u i d volume more an d more c a t a l y s t p a r t i c l e s w i l l be found i n t h e l i q u i d body i n s t e a d o f n e a r o r a t t h e i n t e r f a c e . I n o u r m odel o f a p a r t i c l e i n a u n i t volume, P i g . IB , assum ed t h a t h y d rog en m o le c u le s d ire c tio n s.
i t is
can a p p r o a c h from a l l
T h e r e f o r e , w h at i s r e f e r r e d t o a s a p a r t i c l e p e r
u n i t volume can be c o n s i d e r e d a l s o a s a p a r t i c l e p e r u n i t area of in te rfa c e . I n th e e x p e r i m e n t a l work i t was found t h a t th e d e c r e a s e h y d r o g e n a t i o n v e l o c i t y s t a r t e d i n th e r e g i o n o f 75 t o 90 m l. W ith th e amount o f c a t a l y s t em ployed t h e optimum volume was c a l c u l a t e d to b e beyond th e 75 to 90 m l. r e g i o n and , t h e r e f o r e , c o u l d n o t be shown t o e x i s t .
S in ce t h e optimum volume i s
assumed t o d e c r e a s e w i t h a d e c r e a s e i n t h e amount o f c a t a l y s t , t h e amount o f c a t a l y s t can be r e d u c e d t o a v a l u e such t h a t t h e optimum volume l i e s below t h i s 75 to 90 ml, r e g i o n .
In
F i g . 5 th e u p p e r c u rv e was o b t a in e d w i t h a b o u t 0 . 5 g , ( d r y b a s i s ) o f a W-4 Raney n i c k e l .
The optimum volume f o r th e
am ount o f c a t a l y s t u s e d was c a l c u l a t e d to be i n th e n e i g h b o r hood o f 300 m l.
U sin g a b o u t l / 5 t h e amount o f c a t a l y s t
x x x lli
b r i n g s t h e optimum down to a b o u t 60 m l . , 90 m l. r e g i o n .
o r below th e 75 to
I n t h i s c a s e i t s h o u ld be fo u n d t h a t f o r th e
u s u a l amount o f c a t a l y s t ( c a . 0 . 5 g . d ry b a s i s )
t h e r e i s an
i n c r e a s e i n r a t e w i t h volum e, w h e re a s f o r one f i f t h amount o f ■ c a t a l y s t t h e r e i s no i n c r e a s e i n t h i s same r e g i o n .
That t h i s
was fo u n d to be so i s shown i n th e lo w e r c u r v e , F i g . 5 . The d e c r e a s e , an d f i n a l l y d i s a p p e a r a n c e , o f th e l i q u i d volume e f f e c t w i th d e c l i n e i n c a t a l y t i c a c t i v i t y , and th e d i f f e r e n t o b s e r v a t i o n s made by o t h e r i n v e s t i g a t o r s s u c h a s th e i n c r e a s e i n h y d r o g e n a ti o n v e l o c i t y w i t h i n c r e a s e in s h a k in g f r e q u e n c y , th e d i f f e r e n c e between th e r e g i o n s d e te r m in e d by d i f f u s i o n f a c t o r s and by r e a c t i o n k i n e t i c s , p r o p o r t i o n a l i t y o f th e r a t e to t h e amount o f c a t a l y s t i n th e k i n e t i c s r e g i o n , e t c . , a p p e a r c o n s i s t e n t w i t h w h at can be d ed u ced from ou r m o d el.
S in c e e x p l a n a t i o n s can be o n ly q u a l i t a t i v e a t t h i s
s t a g e , pending' f u r t h e r d a t a , d i s c u s s i o n s o f t h e s e ite m s a r e o m itte d # The n o n - p r o p o r t i o n a l i t y o f t h e amount o f c a t a l y s t to th e o b s e rv e d v e l o c i t y and t h e l i q u i d volume e f f e c t a p p e a r t o be i n t e r r e l a t e d phenomena sty re n e .
in t h e c a s e o f th e h y d r o g e n a t i o n o f
These may be c h a r a c t e r i s t i c o f a r e a c t i o n i n th e
s o - c a l l e d " d i f f u s i o n r e g i o n " where t h e o b s e r v e d k i n e t i c s have no r e l a t i o n t o th o s e t r u l y c h a r a c t e r i s t i c o f th e p r o c e s s . Acknowledgm ent. - The a u t h o r s a r e i n d e b t e d to th e Earshaw O hem ical Oompany f o r f i n a n c i a l s u p p o r t o f t h i s s tu d y .
x z x lv
Summary A m odel h a s b een p r o p o s e d w i t h which c h a n g e s i n th e h y d r o g e n a t i o n v e l o c i t y w i t h l i q u i d volume an d w i t h t h e amount o f c a t a l y s t may b e c a l c u l a t e d .
T h is h a s p ro v ed to b e s u c c e s s
f u l w i t h i n c e r t a i n l i m i t s i n t h e c a s e o f th e h y d r o g e n a t i o n o f s ty re n e to e th y lb e n z e n e .
XXXV
(COETRIBUriOIT FROM THE DEPARTMENT OF CHEMISTRY AlTD THE PURDUE RESEARCH FOUNDATION, PURDUE UNIVERSITY) SOME FACTORS imiTENGING THE ACTIVITY OF RANEY laCKSL CATALYST PART I I I THE EFFECT OF HYDROQEU 01 RANEY NIOKSL CATALYST^ by Y* Yamada w i t h Ed. F . D e g e rin g ^ AH ABSTRACT
1.
A b s t r a c t e d from a t h e s i s s u b m i t t e d t o th e F a c u l t y o f P u rdu e U n i v e r s i t y by Y. Yamada i n p a r t i a l f u l f i l l m e n t o f th e r e q u i r e m e n t s f o r th e d e g re e o f D o c to r o f P h i lo s o p h y , F e b r u a r y , 19 5 0 .
E.
P r e s e n t a d d r e s s : Armour R e s e a r c h F o u n d a tio n o f I l l i n o i s I n s t i t u t e o f T echnology, C h icago , 111. I n c e r t a i n p r o c e d u r e s f o r th e p r e p a r a t i o n o f Raney n i c k e l ,
hy dro gen g a s from a n e x t e r n a l s o u rc e i s employed in some o f th e s te p s .
3.
Raney® c l a i m s t h a t th e c a t a l y t i c p r o p e r t i e s o f th e
M. Raney, Ü. S. P a t e n t 1 ,9 1 5 ,4 7 2 (Ju ne 27, 1 9 3 3 ).
m a t e r i a l o b t a i n e d a f t e r th e l e a c h i n g o f th e a l l o y and s u b s t a n t i a l l y w ash in g i t f r e e from a l k a l i , may be enhanced by t r e a t m e n t w i t h h y d ro g en u n d e r s u i t a b l e c o n d i t i o n s o f t e m p e r a t u r e and p r e s s u r e .
I n t h e p r e p a r a t i o n of t h e W-6
xxxvi
c a t a l y s t ^ , w hich i s c o n s i d e r e d t o be th e m o st a c t i v e n i c k e l
4.
A dk ins and B i l l i c a , £•
Qhem. S oc. , 7 0 , 695 ( 1 9 4 8 ),
c a t a l y s t , w a sh in g o f t h e c a t a l y s t i s c a r r i e d out u n d e r a s l i ^ t h y d ro g en p r e s s u r e .
A c c o rd in g to A dk ins and B i l l i c a ^ ,
t h e u se o f hydro g en u n d e r p r e s s u r e i n t h e w a s h in g p r o c e s s may be a d v a n ta g e o u s i n t h a t i t p r o t e c t s th e c a t a l y s t from c o n t a c t w i t h a i r an d t h e l o s s o f th e r a t h e r l a r g e q u a n t i t y o f hy d ro g en w h ich i s a d s o r b e d on t h e c a t a l y s t .
The a c t i v i t y o f Raney
n i c k e l c a t a l y s t d e c l i n e s a s t h e h y d ro gen a d s o r b e d by the m e ta l i s l o s t b u t th e two b e h a v i o r s a r e n o t p a r a l l e l ® .
6.
S c h r o t e r i n "Newer Methods of P r e p a r a t i v e O rganic Chem i s t r y " , I n t e r s c i e n c e P u b l i s h e r s , I n c . , New Y ork, N. Y . , 1 9 4 8 , - p . .6 8 . Sometimes i t i s d e s i r a b l e to use t h e same c a t a l y s t sample
two o r more t i m e s i n c o m p a ra tiv e h y d r o g e n a t i o n r u n s i n o r d e r to e lim in a te u n c e r t a i n t i e s in c a t a l y s t f a c t o r s .
This i s
e s p e c i a l l y so i n th e c a s e o f Raney n i c k e l w h ich h a s to be h a n d le d u n d e r l i q u i d , making i t d i f f i c u l t to w e ig h sam ples p re c ise ly .
I n o r d e r t o u s e a c a t a l y s t sam ple more th a n once
i t i s n e c e s s a r y t h a t th e a c t i v i t y o f t h e c a t a l y s t be m a i n t a i n e d a f t e r a p re v io u s ru n .
Hydrogen g a s may be u s e d f o r t h i s p u rp o se
E x p e r i m e n t a l . - M a t e r i a l s , a p p a r a t u s and p r o c e d u r e were d e s c r i b e d i n th e A b s t r a c t , P a r t I ,
of t h i s th e s is .
R e s u l t s and D i s c u s s i o n . - When 25 m l. o f s t y r e n e i s
xxxvii
h y d r o g e n a t e d o v e r Raney n i c k e l w i t h o u t any s o l v e n t , due to t h e e x o th e r m ic n a t u r e o f the r e a c t i o n , th e t e m p e r a t u r e o f t h e r e a c t i o n m i x t u r e g o e s up t o a b o u t 60*0.
Im m e d ia te ly a f t e r
c o m p le tio n o f th e r e a c t i o n , th e r e a c t i o n f l a s k c o n t a i n i n g t h e p r o d u c t i s rem oved from t h e a p p a r a t u s and c o o l e d u n d e r r u n n in g w a t e r t o room t e m p e r a t u r e .
A n o th e r 25 m l. p o r t i o n i s added
to t h e p r o d u c t a n d h y d r o g e n a t e d o v e r t h e same c a t a l y s t sample as b e fo re .
I t i s fo u n d t h a t th e o b s e rv e d h y d r o g e n a tio n
v e l o c i t y i s n o t t h e same a s t h a t o b t a i n e d w ith a m i x t u r e o f s t y r e n e , e t h y l b e n z e n e and f r e s h c a t a l y s t i n th e am ounts e q u i v a l e n t to t h a t p r e s e n t a t t h e s t a r t o f th e second h y d r o g e n a t i o n above ( c f . F i g . 1 ) .
In o t h e r w o rds, th e a c t i v i t y o f
t h e c a t a l y s t a f t e r th e f i r s t ru n has somehow d e c r e a s e d .
If,
how ever, th e m i x t u r e a f t e r c o m p le tio n o f th e f i r s t ru n i s a llo w e d to c o o l down to room t e m p e r a tu r e g r a d u a l l y u n d e r h y d ro g en p r e s s u r e , i . e . , by l e a v i n g th e r e a c t i o n f l a s k c o n t a i n i n g t h e p r o d u c t i n th e a p p a r a t u s w i t h o u t r e l e a s i n g th e h y d ro g e n , a h i g h e r r a t e i s o b t a i n e d w hich i s a b o u t th e same a s t h a t o b t a i n e d by h y d r o g e n a t i n g a m ix tu re o f s t y r e n e , e t h y l b e n z e n e and f r e s h c a t a l y s t i n th e same am ounts a s p r e s e n t a t t h e s t a r t o f t h i s seco n d ru n ( o f . F i g . z K
From t h i s i t
may b e c o n c lu d e d t h a t h y d ro g en h e l p s i n m a i n t a i n i n g th e a c t i v i t y o f th e c a t a l y s t . Two c a t a l y s t sam p les w hich gave t h e same r a t e on a b l a n k r u n on 25 m l. o f s t y r e n e were u s e d f o r t h i s t e s t .
A fte r
c o m p le tio n o f th e r u n , th e f l a s k c o n t a i n i n g one sample and
x x x v iii
F ig . 1
E f f e c t o f R apid C o o lin g o f C a t a l y s t i n Open A ir
Hydrogen A bsorbed p . 8 .1 . 15.0
10.0
5.0
0
0
5
10
15
Time — m in u te s o B lan k Run + Second r u n o v e r t h e same c a t a l y s t .
x x x ix
F ig . 2 E f f e c t o f Gradual C oolin g o f C a t a ly s t under Hydrogen P r essu re
1 5 .0 Hydrogen Absorbed
10.0
Hi
5 .0
Blank run Second run over the same c a t a l y s t
0
10
Time
minutes
xl
t h e p r o d u c t e t h y l b e n z e n e was f l u s h e d w i t h hy d ro gen g a s and s to p p e re d .
The o t h e r was s t o p p e r e d i n open a i r .
A fte r 5 days,
25 m l. p o r t i o n o f s t y r e n e w as added t o e a c h f l a s k and h y d r o g e n a te d o v e r t h e same c a t a l y s t sa m p le s . in P i g . 3 .
The r e s u l t s a r e g iv e n
The k e e p in g q u a l i t y o f Raney n i c k e l i n a l i q u i d
u n d e r an a tm o sp h e re o f h yd ro g en i s a p p a r e n t l y b e t t e r th a n i n a liq u id under a i r .
I n v iew o f t h e l i q u i d volume e f f e c t and
t h e s o l v e n t e f f e c t o f th e e th y lb e n z e n e p r e s e n t i n t h e b e g i n n i n g o f t h e seco nd r u n and w h ich was n o t p r e s e n t i n t h e b l a n k r u n , even th o u g h th e r a t e
o f th e
ru n p r a c t i c a l l y m a tc h e s th e
b la n k s , th e a c t i v i t y
o f th e
c a t a l y s t m u st be c o n s i d e r e d to
have d e c r e a s e d .
T h is may be due t o some l e a k a g e .
A c t i v i t y o f t h e c a t a l y s t i s b e t t e r m a in t a i n e d i n a l i q u i d u n d e r h y d ro g en p r e s s u r e o f a few a t m o s p h e r e s .
The h y d ro
g e n a t i o n c u rv e o f 25 m l. o f s t y r e n e o v e r one l e v e l s p o o n f u l o f c a t a l y s t (c a . 0 .9 in P ig . 4.
The p r o d u c t
g . m o i s t w e ig h t i n d io x an ) i s shown was
asI
a llo w e d t o c o o l g r a d u a l l y to
t e m p e r a t u r e by s t a n d i n g f o r 90 m in. u n d e r 38 p s i . gage p r e s s u r e o f h y d ro g e n .
A seco n d 26 m l. p o r t i o n o f s t y r e n e was h y d r o
g e n a t e d o v e r th e same c a t a l y s t sample ( o f . IX i n P i g . 4 ) . The p r o d u c t w as t h e n a l l o w e d t o s t a n d f o r 15 h r s . u n d e r '38 p s i . gage p r e s s u r e o f h y d ro g e n .
A t th e end o f th e p e r i o d , 26 m l.
o f t h e e t h y l b e n z e n e was removed, and 25 m l. o f s t y r e n e h y d r o g e n a te d o v e r t h e same c a t a l y s t sample f o r th e t h i r d ti m e . The h y d r o g e n a t i o n c u rv e r e a c h e d the same maximum s lo p e b u t was s lo w e r i n r e a c h i n g i t (Curve I I I , P i g . 4 ) . The above e x p e r i m e n t s p ro v e t h e r e t e n t i o n o f c a t a l y t i c
room
x li
F ig . 3 Keeping Q u a lity o f C a t a ly s t InaL iq u ld under Hydrogen
15.0 HYDROGEN ABSORBED p.8.1. Blank Runs 1 6 A -I, 1 6 c -I
10.0
/ f
—— Run 19B—I I ( s t o r e d under hydrogen)
5 .0
—— -Run 19A—I I ( s t o r e d under air) 0.00
5
10 TIME — m in u te s
15
20
x lii
F ig . 4
E f f e o t o f S to ra g e o f C a t a ly s t under Hydrogen P r essu re
20.0 Hydrogen Absorbed
in
p . 8 .1 15.0
10.0
5 .0
0 5
10 Time —
15 minutes
20
x liil
a c t i v i t y u n d e r h y d ro g e n .
Ho c a s e o f en h an ced a c t i v i t y due t o
above t r e a t m e n t was o b s e r v e d . Acknowledgm ent. - The a u t h o r s a r e i n d e b t e d to the. Harshaw C hem ical Company f o r f i n a n c i a l s u p p o r t o f t h i s s tu d y . Summary The k e e p in g q u a l i t y o f Raney n i c k e l in a l i q u i d u n d e r hy d ro g en p r e s s u r e was d e m o n s tr a te d .
A c a t a l y s t sam ple may be
u s e d two o r more tim e s i n a s e r i e s o f c o m p ariso n r u n s , e l i m i n a t i n g u n c e r t a i n t i e s i n r e g a r d to c a t a l y t i c f a c t o r s .
S O m FACTORS lilFLUEIICniG TEE ACTIVITY OF
RAIBY HI0IC5L CATALYST IHTROLUCTIOH The m o st common n i c k e l c a t a l y s t u s e d i n l a b o r a t o r y p r a c t i c e to d a y i s Raney n i c k e l .
I t s h ig h a c t i v i t y p e r m i t s u s e
o f g e n e r a l l y m ild c o n d i t i o n s i n many h y d r o g e n a t i o n r e a c t i o n s w h ile i t s r e l a t i v e l y low c o s t and s i m p l i c i t y o f p r e p a r a t i o n make i t e a s i l y a v a i l a b l e f o r u s e .
I t h as been shown to have
a w ide ra n g e o f a p p l i c a t i o n ( 1 , 2 3 , 3 2 , 3 7 ) . A lth o u g h a c o n s i d e r a b l e am ount o f work h a s b e e n p u b l i s h e d d e a l i n g w i t h th e u se o f Raney n i c k e l , l i t t l e b een g i v e n t h e c a t a l y s t i t s e l f .
c o n s id e ra tio n has
T his i s u n d e r s t a n d a b l e s i n c e
th e o r g a n i c c h e m i s t ' s i n t e r e s t i s in th e compound(s) he w a n ts t o h y d r o g e n a te o r p ro d u ce and a c a t a l y s t p r e p a r e d by any one o f th e s t a n d a r d p r o c e d u r e s ( 2 , 3 , 6 , 2 9 , 3 6 ) i s g e n e r a l l y s a t i s fa c to ry f o r h is purpose.
With c a t a l y s t s of h i g h a c t i v i t y
a l r e a d y a v a i l a b l e , a s tu d y o f Raney n i c k e l and some o f th e f a c t o r s w h ich a f f e c t i t s a c t i v i t y becomes o ne, more o f a f u n d a m e n ta l n a t u r e , th a n one w i t h an im m ediate p r a c t i c a l purpose,
n e v e r t h e l e s s , a b e t t e r a p p r e c i a t i o n o f some o f th e
f a c t o r s w hich i n f l u e n c e th e a c t i v i t y o f th e c a t a l y s t means a b e t t e r u n d e r s t a n d i n g o f t h e p r e p a r a t i o n , s t o r a g e and h a n d l i n g of th e c a t a l y s t . Ho a t t e m p t was made t o c o r r e l a t e any p h y s i c a l p r o p e r t y o f th e c a t a l y s t w i t h th e o b s e rv e d r a t e s o f h y d r o g e n a tio n ( 1 8 ,3 5 ) a l t h o u g h an i n c i d e n t a l o b s e r v a t i o n was made i n one
c a s e , t h a t t h e more a c t i v e o f two c a t a l y s t s had th e lo w e r d e n s ity . The e f f e o t o f s t o r a g e and age on a c a t a l y s t h a s b e e n d e s c rib e d in th e l i t e r a t u r e
( 2 9 ,3 2 ,5 7 ) w i t h s t a t e m e n t s o f a
v e r y g e n e r a l n a t u r e to th e e f f e c t t h a t th e a c t i v i t y o f th e c a t a l y s t i s s t i l l good a h a l f y e a r o r a y e a r a f t e r p r e p a r a t i o n . P a t t i s o n h a s made a more s y s t e m a t i c s tu d y o f th e age f a c t o r and h a s o b s e rv e d t h a t Raney n i c k e l l o s e s a c t i v i t y s h o r t l y a f t e r i t i s p r e p a r e d an d more s lo w ly a s tim e goes on ( 3 1 ) . th e sis,
In th i s
th e e f f e o t o f age and t h e k e e p in g q u a l i t y o f th e
c a t a l y s t u n d e r h y d ro g en w ere i n v e s t i g a t e d . H y d r o g e n a tio n s o f s t y r e n e , c y e lo h e x e n e , m a le io a c i d , e t h y l m a l e a t e , b e n a a ld e h y d e , a c e t o n e , m e th y l i s o b u t y l k e to n e and a l l y l a l c o h o l showed v a r i o u s o r d e r s o f m ag nitu de i n th e o b s e rv e d r a t e s o f h y d r o g e n a t i o n and d i f f e r e n t s h a p e s o f h y d r o g e n a t io n c u r v e s .
I n o t h e r w o rd s, a s tu d y o f c a t a l y t i c
a c t i v i t y u s in g a c h e m ic a l r e a c t i o n i s c o m p lic a te d by a f a c t o r d e p e n d in g on th e s t r u c t u r e o f th e h y d ro g e n a c c e p t o r . found more p r o f i t a b l e , few r e a c t i o n s .
th e re fo re ,
I t was
to c o n c e n t r a t e on o n ly a
The r e s u l t s o b t a i n e d w i t h s t y r e n e a r e
p r e s e n t e d i n t h i s t h e s i s s i n c e more d e f i n i t e c o n c l u s i o n s a b o u t t h e a c t i v i t y o f th e c a t a l y s t c o u ld be made from th e h y d r o g e n a t i o n o f t h i s compound.
PART I DBVSLOHîEHT OF AH ACTIVITY TEST In tro d u c tio n I n o r d e r t o d e te r m in e and e v a l u a t e f a c t o r s w h ich may i n f l u e n c e the a c t i v i t y of Raney n i c k e l c a t a l y s t , some means o r m ethod o f m e a s u rin g o r c h e c k in g th e a c t i v i t y o f th e c a t a l y s t i s f i r s t n e c e s s a r y so t h a t any ch an g es i n t h e a c t i v i t y can he o b s e rv e d and c a u s e s a s s i g n e d to th e p r o p e r f a c t o r s . A tte m p ts have b e e n made, n o t s u c c e s s f u l l y ,
to r e l a t e
m e a s u ra b le p h y s i c a l p r o p e r t i e s o f a c a t a l y s t to i t s a c t i v i t y
(18)
Raney (35) w r i t e s t i j a t w h ile th e c a t a l y t i c p r o p e r t y may be a s s o c i a t e d w i t h s p e c i f i c g r a v i t y , s t a t e o f s u b d i v i s i o n , mag n e t i c o r p y r o p h o r i c p r o p e r t i e s o f th e c o n t a c t s u b s t a n c e , i t i s n o t d e te r m in e d by them o r by any o t h e r m e a s u ra b le c h a r a c t e r i s t i c s of t h e m e t a l . The a c t i v i t y of a c a t a l y s t I s more o f t e n d e te r m in e d by c a r r y i n g o u t a g iv e n c h e m ic a l r e a c t i o n .
The r a t e o f th e c a t a
l y z e d r e a c t i o n o r fne e x t e n t ( a s e x p r e s s e d by t . e p e r c e n t y i e l d ) o f th e r e a c t i o n i s u s u a l l y ta k e n a s th e m easure o f the c a ta ly tic a c tiv ity . R ate h a s b e e n e x p r e s s e d i n v a r i o u s ways due p r i m a r i l y to th e f a c t t h a t h y d r o g e n a t i o n r a t e s a r e n o t alw ay s c o n s t a n t th r o u g h o u t a r e a c t i o n .
When t h e r a t e i s c o n s t a n t , t h e s l o p e
o f th e amount o f hydrogen a b s o r b e d - tim e c u rv e may be ta k e n a s th e m easure o f t h e a c t i v i t y .
As a m a t t e r o f f a c t , Maxted and
Evans (26) c a l l th e sLope in a z e ro o r d e r r e a c t i o n ,
th e
a c t i v i t y o f th e c a t a l y s t . a
O fte n , th e tim e r e q u ir e d to c o m p le te
g iv e n h y d ro g e n a tio n i s u s e d a s an i n d i c a t i o n of th e
a c tiv ity . p o in t.
T h is i s th e m ost s i g n i f i c a n t from a p r a c t i c a l s ta n d
I n some i n s t a n c e s ,
th e tim e r e q u i r e d f o r th e h y d ro
g e n a tio n o f th e m id d le 60 p e r c e n t , i . e . ,
d i s r e g a r d i n g th e f i r s t
and l a s t 20 p e r c e n t o f th e r e a c t i o n , i s u s e d a s a b a s i s of co m p a riso n ( 7 ) .
k i r k p a t r i c k (21) u s e s th e s lo p e of volume o f
h y d ro g e n -a b s o rb e d tim e c u rv e a t i t s f l e x p o i n t a s th e m easure o f th e a c t i v i t y .
S m ith and c o -w o rk e rs (38) have u se d a k ir s tio
a p p ro a c h w h ic h a llo w s th e t a b u l a t i o n o f r a t e c o n s ta n ts r a t h e r th a n tim e s r e q u i r e d f o r co m p lete h y d r o g e n a tio n .
In t h i s c a s e ,
h o w ever, t h e i r p rim a ry i n t e r e s t i s i n th e r e a c t a n t s and n o t i n th e c a t a l y s t . The h y d ro g e n a tio n o f some u n s a tu r a te d compound, w h ich i s sm o o th ly and q u a n t i t a t i v e l y h y d ro g e n a te d to a s i n g l e p r o d u c t, may s e rv e a s a t e s t r e a c t i o n .
To c i t e a few ex am p les, th e
h y d ro g e n a tio n o f a c e to n e to is o p r o p y l a l c o h o l , e t h y l a c e t o a o e t a t e to e t h y l b e t a - h y d ro x y b u ty ra te ( l ) , and b e n z a ld e h y d e to b e n z y l a lc o h o l (2 4 ). B e fo re a tte m p tin g to w ork o u t a
p ro c e d u re f o r t e s t i n g a
c a t a l y s t u s in g a p a r t i c u l a r hydrogen a c c e p to r , th e r e a c t i o n m u st b e s t u d i e d in d e t a i l so t h a t c r i t i c a l f a c t o r s in f lu e n c in g th e r a t e o f th e h y d ro g e n a tio n a r e known and u n d e r s to o d .
As
i t a p p e a r s now, i t i s c e r t a i n l y a n a iv e a p p ro a c h to a tte m p t to d e te rm in e r e l a t i v e a c t i v i t i e s o f c a t a l y s t s or th e r a p i d i t y o f h y d r o g e n a tio n o f d i f f e r e n t c l a s s e s o f u n s a tu r a te d compounds
by co m p arin g ru n s made on a r b i t r a r i l y s e l e c t e d q u a n t i t i e s o f h y d ro g e n a c c e p t o r , s o lv e n t and c a t a l y s t ( 9 ) . The c a t a l y t i c h y d ro g e n a tio n o f s ty r e n e to e th y lb e n z e n e was u s e d by P a t t i s o n (31) a s a t e s t r e a c t i o n i n d e te r m in in g th e a c t i v i t y o f Raney n i c k e l p r e p a r a t i o n s an d in e v a l u a t i n g th e p o is o n in g e f f e c t o f o rg a n ic h a lo g e n compounds*
He p r o p o s e s
t h r e e e m p ir ic a l t e s t s i n v o lv in g s ty r e n e i n e th a n o l, s ty r e n e i n d io x a n , an d s ty r e n e w ith o u t s o lv e n t f o r e v a l u a t i n g c a t a l y t i c a c tiv ity *
I n t h i s t h e s i s some f a c t o r s i n f l u e n c in g th e
m easu red r a t e o f t h i s r e a c t i o n when c a r r i e d o u t i n a P a r r lo w p r e s s u r e s h a k in g a p p a r a tu s a r e i n v e s t i g a t e d so t h a t t e s t p r o c e d u r e s may be c o n t r o l l e d and s ta n d a r d iz e d and e x p e r im e n ta l r e s u l t s p r o p e r ly i n t e r p r e t e d * The p r o c e s s o f c o n v e r tin g s ty r e n e to e th y lb e n z e n e i s o f no i n d u s t r i a l im p o rta n c e s in c e th e d e s ir e d p r o c e s s i s th e r e v e r s e o f t h i s ( 2 8 ) , b u t th e r e a c t i o n le n d s i t s e l f w e l l to an I n v e s t i g a t i o n o f th e m echanism and r a t e s o f c a t a l y t i c h y d ro g e n a tio n o f a s o - c a l l e d " p rim a ry ” d o u b le bond.
F i r s t , w ith
Raney n i c k e l i n th e c o ld and a t o r d in a ry p r e s s u r e s , s t y r e n e g iv e s o n ly one p r o d u c t, e th y lb e n z e n e ( 1 0 ,3 2 ) .
The a lk e n e
lin k a g e i s s a t u r a t e d u n d e r m ild e r c o n d i t i o n s th a n th o s e r e q u i r e d f o r th e h y d ro g e n a tio n th e b e n z e n o id r i n g so t h a t th e s e l e c t i v e h y d ro g e n a tio n o f s ty r e n e to e th y lb e n z e n e i s e a s i l y a c c o m p lish e d i n th e v a p o r o r l i q u i d p h a se . h y d ro g e n a te d a t a c o n v e n ie n t r a t e
S econd, s ty r e n e i s
(31) and c o n d i t i o n s can be
ch o se n so t h a t th e h y d ro g en i s a b s o rb e d a t a p r a c t i c a l l y c o n s ta n t r a t e .
L iq u id p h ase h y d r o g e n a tio n o f s ty r e n e to e th y lb e n z e n e h a s b een s tu d i e d w ith c a t a l y s t s o th e r tn a n Raney n i c k e l ( 2 0 ,3 4 .5 9 .4 0 ) . The h y d ro g e n a tio n o f s ty r e n e h a s been u sed in a few s t u d i e s on th e r e l a t i v e r a t e s o f c a t a l y t i c h y d ro g e n a tio n o f d i f f e r e n t ty p e s o f u n s a tu r a t e d com pounds,
D upont (10) h a s
com pared th e h y d ro g e n a tio n r a t e s o f s e v e r a l c l a s s e s o f e t h y l e n i c compounds o v e r Raney n i c k e l in th e c o ld and a t o r d in a r y p r e s s u r e s and h a s found t h a t th o s e c o n ta in in g a te r m i n a l d o u b le bond, su ch a s s ty r e n e , w ere r a p i d l y re d u c e d . L e b ed ev , K o b lia n sk y and Y abubchik (22) have c a r r i e d o u t a s i m i l a r i n v e s t i g a t i o n u s in g p la tin u m b la c k c a t a l y s t . The h y d ro g e n a tio n o f s ty r e n e h as b e e n u se d in th e t e s t o f th e " tu n n e l" th e o ry o f h e te ro g e n e o u s c a t a l y s i s ( 8 ) . E x p e rim e n ta l A p p a ra tu s an d P ro c e d u re Low p r e s s u r e l i q u i d p h ase h y d r o g e n a tio n s may be ru n a t Con s t a n t h y d ro g en p r e s s u r e and th e c o u rs e o f th e r e a c t i o n s fo llo w e d by th e volume change o r a t c o n s ta n t volume and th e r e a c t i o n f o l low ed by p r e s s u r e change i n h y d ro g e n .
A summary o f th e g e n e r a l
h y d ro g e n a tio n te c h n iq u e u se d in k i n e t i c s t u d i e s and o f f a c t o r s i n f l u e n c in g th e k i n e t i c s o f h y d ro g e n a tio n s c a r r i e d o u t a t con s t a n t p r e s s u r e i s g iv e n by M axted ( 2 5 ) .
The c o n v e n tio n a l h y d ro
g e n a tio n a p p a r a tu s d e s c r ib e d by Adams and V oorhees (14)
( o r th e
s i m i l a r co m m ercial m odel made by th e P a r r I n s tr u m e n t C o ., I n c . , M o lin e , 1 1 1 .) i s a c o n s ta n t volum e sy ste m in w hich th e h y d ro gen co n su m p tio n i s d e te rm in e d i n te rm s o f p r e s s u r e m easu red on
a B ourdon gauge a t t a c h e d t o th e h y d ro g en ta n k o f th e a p p a r a tu s . S m ith and o o -w o rk e rs (38) have p u b lis h e d a r e c e n t s e r i e s o f p a p e r s on th e k i n e t i c s o f th e h y d r o g e n a tio n o f c e r t a i n o r g a n ic compounds u s in g t h i s ty p e o f a p p a r a tu s .
The a p p a r a tu s p e r m its
l a r g e r s c a l e (6 to 10 l i t e r s o f hydrogen) h y d r o g e n a tio n s more c o n v e n ie n tly th a n c a n be a c c o m p lis h e d w ith th e c o n s t a n t p r e s s u re s e t- u p s in c e th e h y d ro g en r e q u ir e d can be s to r e d u n d e r 2 to 6 a tm o sp h e re s p r e s s u r e .
I f l e s s th a n 1 t o 2 l i t e r s o f
h y d ro g en i s u se d i n th e r e a c t i o n and i f i t i s p e rfo rm e d a t a tm o s p h e ric p r e s s u r e ( o r a t s e v e r a l cm .Eg. p r e s s u r e ) , th e h y d ro g en c o n su m p tio n i s b e t t e r d e te rm in e d v o l u m e t r i c a l l y . A s ta n d a r d lo w - p r e s s u r e s h a k in g a p p a r a t u s , p u rc h a s e d from th e P a r r I n s tr u m e n t G o ., I n c . , w as u sed f o r th e e x p e r im e n ts . The c a p a c ity o f th e m e ta l ta n k i s 4107 m l.
The r e a c t i o n i s ru n
in a h e a v y -w a lle d g l a s s f l a s k o f a b o u t 375 m l.- c a p a c i t y .
The
m o to r i s r a t e d a t 1725 r .p . m . w h ich i s re d u c e d a b o u t l / 7
so
t h a t th e f l a s k i s sh ak en a t a b o u t 250 o s c i l l a t i o n p e r m in u te . A Dry I c e - a c e t o n e c o o le d m e ta l t r a p i s p la c e d b etw een th e hy d ro g en ta n k and th e r e a c t i o n b o t t l e . a d v a n ta g e s to t h i s .
T here a r e s e v e r a l
The hydrogen ta n k i s p r o te c t e d from th e
o r g a n ic v a p o r s from th e r e a c t i o n b o t t l e .
The h y d ro g en ta n k i s
k e p t more n e a r l y a t c o n s t a n t te m p e r a tu re and th e p r e s s u r e r e a d in g i s n o t a f f e c t e d by s l i g h t p r e s s u r e in c r e a s e due to i n c r e a s e in g a s te m p e r a tu re in an e x o th e rm ic r e a c t i o n .
The
gauge n e e d le i s s t e a d i e r s in c e i t i s n o t s u b je c t to s u r g e s due to th e s h a k in g .
The p r e s s u r e gauge i s r e a d w ith a m e n isc u s r e a d e r .
H ot
o n ly d o e s i t g iv e an e n la r g e d view of th e gauge m a rk in g h u t i t a l s o i n s u r e s r e a d in g s a t r i g h t a n g le s to th e f a c e o f th e gags. The c h a rg e to be h y d ro g e n a te d i s in tr o d u c e d i n t o th e r e a c t i o n b o t t l e , w hich i s th e n a t t a c h e d to th e a p p a r a tu s .
The
f l a s k i s e v a c u a te d t h r e e tim e s , b e in g f i l l e d w ith h y d ro g en a f t e r ea ch e v a c u a tio n .
A f te r a d j u s t i n g th e hydro g en p r e s s u r e to th e
d e s i r e d i n i t i a l gauge p r e s s u r e r e a d in g , th e sy stem i s a llo w e d to s ta n d a w h ile .
F o r a s e r i e s o f co m p ariso n r u n s , th e
l e n g t h o f tim e th e c a t a l y s t i s k e p t in c o n ta c t w i th th e s ty r e n e b e f o r e s t a r t i n g th e s h a k in g i s s ta n d a r d iz e d .
The i n i t i a l
h y d ro g en p r e s s u r e g e n e r a l ly u s e d was 4 5 .0 p . s . i . gauge r e a d in g and th e c o n t a c t tim e , 11 m in u te s . A s to p w atch i s s t a r t e d s im u lta n e o u s ly w ith tr.e s h a k in g . R e a c tio n s a r e s t a r t e d a t room te m p e r a tu r e .
The te m p e r a tu re o f
th e h y d ro g en ta n k i s reocrded w ith each p r e s s u r e r e a d in g . P r e s s u r e i s r e a d to th e c l o s e s t 0 .1 p . s . i . on th e g au g e.
The
te m p e r a tu re change on th e o u ts id e of th e r e a c t i o n f l a s k i s fo llo w e d w ith an i r o n - c o n s t a n t a n th erm o co u p le u sed in c o n ju n c tio n w i t h a L eed s and IT orthrup p o te n tio m e te r i n d i c a t o r . R e a d in g s a r e made to th e n e a r e s t 0 .5 ^ 0 .
The th erm o c o u p le
ju n c tio n i s p la c e d a g a i n s t th e s id e o f th e f l a s k a f ix e d d i s t a n c e from th e b o tto m o f th e f l a s k and c o v e re d w ith an a s b e s to s s h e e t.
These a r e h e ld in p la c e by th e snug f i t o f
th e m e ta l b o t t l e g u a r d .
T h is a rra n g e m e n t d o es n o t g iv e th e
te m p e ra tu re o f th e r e a c t i o n m ix tu re f o r w h ic h a th erm o c o u p le
p la c e d I n d i r e c t c o n t a c t w ith th e l i q u i d m ix tu re i s more s u i t a b le .
I t i s a d e q u a te f o r f o llo w in g te m p e r a tu re c h a n g e s i n th e
r e a c t i o n m ix tu r e . M a te ria ls Raney n i c k e l a l l o y (50 p e r c e n t H i) was f u r n i s h e d by th e H arshaw Gh em ica1 C o ., G hem ical, O h io . L in d e ta n k h y d ro g en was u se d w ith o u t f u r t h e r p u r i f i c a t i o n . S ty r e n e w as Eastm an Kodak Go. w h ite l a b e l g ra d e .
I n th e
b e g in n in g , th e i n h i b i t o r w as rem oved by w ash in g th e s ty r e n e w i t h a l k a l i s o l u t i o n fo llo w e d w ith w a te r , th e n d r y in g w ith c a lc iu m c h l o r id e (13) o r rem oving th e w a te r by f r e e z i n g a t -1 5 ° u s in g an i c e - s a l t m ix tu re ( 1 7 ) , and f i n a l l y d i s t i l l i n g th e s ty r e n e u n d e r re d u c e d p r e s s u r e (a b o u t 15 mm. E g .) a t a b o u t 40t
S ty re n e l e f t s ta n d in g f o r a s h o r t tim e gave low r a t e s so
t h a t i t had to be f r e s h l y d i s t i l l e d b e f o r e u s e .
I t was soon
found t h a t s t y r e n e c o n ta in i n g an i n h i b i t o r gave a b o u t th e same r e s u l t a s f r e s h l y d i s t i l l e d s ty r e n e so th e tr e a tm e n t to remove th e i n h i b i t o r w as ab an d oned (a£® 1 .5 4 3 3 ) . Gommero l a l a b s o lu te e th a n o l was r e f lu x e d an h o u r w ith some Raney n i c k e l th e n d i s t i l l e d
(n^® 1 .3 6 0 1 ) .
S ty re n e i s p r a c t i c a l l y q u a n t i t a t i v e l y c o n v e r te d to e t h y l b e n ze n e ( b . p . 1 3 4 .5 -1 3 4 .8 d e g r e e s , u n c o r r e c te d , n^^ 1 .4 9 3 0 ) . D i f f e r e n t am ounts o f a l i q u i d m ix tu re o f s ty r e n e in e th a n o l i n 1 :2 volum e r a t i o w ere h y d ro g e n a te d o v er d i f f e r e n t q u a n t i t i e s o f Raney n i c k e l a t r a t e s ra n g in g from 0 .4 5 p . s . i . / m i n . to 2 .3 0 p . s . i . / m i n . a b o u t th e sam e.
The r e f r a c t i v e i n d i c e s of th e p r o d u c ts w ere
10
Table 1 C o n sta n c y o f P r o d u c t Formed a t D i f f e r e n t R a te s o f H y d ro g e n a tio n Run 2-64A 2-65A 2-62A 2-61B 2-63A 2-61A
S ty r e n e - e t h a n o l 1 :2 volume r a t i o 75 m l. 60 50 75 60 60
C a ta ly s t
R ate
0 .0 9 4 1 g . 0 .1 0 7 2 0 .1 0 7 6 0 .4 8 4 7 0 .4 9 0 2 0 .4 8 3 0
0 .4 6 0 .4 5 0 .7 0 2 .3 0 1 .9 0 1 .6 0
P r o d u c t, n^® li r.
1 .4 0 9 6 * 1 .4 0 7 0 1 .4 0 7 0 1 .4 0 6 9 1 .4 0 7 9 1 .4 0 7 0
*The l i q u i d and c a t a l y s t were s e p a r a te d by s u c ti o n in a s i n t e r e d g l a s s c r u c i b l e . A bout 5 m l. of l i q u i d was l o s t i n th e p r o c e s s , i n d i c a t i n g l o s s by e v a p o r a tio n . The o t h e r l i q u i d s w ere s e p a r a t e d by d é c a n t a tio n from th e s e t t l e d c a t a l y s t s These gave more c o n s i s t e n t r e s u l t s , ( C a t a l y s t , Hi (R) 2 -6 3 , age 1 week) • M easurem ent o f th e Amount o f C a t a l y s t Raney n i c k e l , due to i t s p y ro p h o ric n a t u r e , h a s t o be h a n d le d u n d e r l i q u i d .
T h is in tr o d u c e s some d i f f i c u l t y i n
w e ig h in g o u t d e s i r e d am ounts o f c a t a l y s t . I n p r e p a r a t i v e o r g a n ic c h e m is tr y , i t i s fo u n d more co n v e n i e n t to m easure by volume than t o w eig h th e c a t a l y s t . m i l l i t e r (m o is t)
One
o f th e c a t a l y s t w eig h s a b o u t 3 g . ( 1 ,2 9 ) .
The c a t a l y s t can be h a n d le d c o n v e n ie n tly in s o l i d i f i e d c o t t o n s e e d o i l o r o t h e r o r g a n ic s o l i d s ( 3 1 ) .
I n t h i s form c a t a l y s t
sa m p le s may be w eig h ed o u t a c c u r a t e l y .
S im ila r m ethods o f s t o r
ag e and h a n d lin g o f c a t a l y s t sa m p le s have b een r e p o r t e d by Raney (35) and by M axted and T i t t ( 2 7 ) . A n o th e r m ethod o f g e t t i n g aro u n d th e d i f f i c u l t y w ould be to s t a r t w ith e q u a l q u a n t i t i e s o f th e a l l o y , each s u f f i c i e n t f o r a s i n g l e r u n , and to c o n t r o l th e a t t a c k on each sam ple
11
by th e a l k a l i n e s o l u t i o n by m e a s u rin g th e e v o lu tio n of h y d ro g en The a t t a c k i s e x te n d e d u n t i l th e same am ount o f h y d r o g è n e s i s c o lle c te d (3 2 ). Som etim es i t i s p o s s i b l e to make a c o r r e c t i o n i n th e mea s u re d r a t e by a llo w in g f o r th e d i f f e r e n c e i n c a t a l y s t w e ig h t. S m ith and c o -w o rk e rs (38) r e f e r s th e m e a su re d r a t e c o n s ta n t i n th e h y d ro g e n a tio n o f c e r t a i n u n s a tu r a te d compounds to 1 g . o f Raney n i c k e l c a t a l y s t by m u lt ip ly in g th e r a t e c o n s ta n t a c t u a l l y o b ta in e d by th e r e c i p r o c a l o f th e c a t a l y s t w e ig h t.
T h is m ethod
i s o n ly p o s s i b l e when, th e r a t e m easu red i s p r o p o r t i o n a l to th e am ount o f c a t a l y s t .
T h is i s n o t so in a l l r e a c t i o n s .
F o r m e a s u rin g o u t s u c c e s s iv e e q u a l m ounts o f c a t a l y s t , a s m a ll g l a s s spoon h a s b een found to be u s e f u l ( 3 1 ) .
By a
r o u t i n e sy ste m o f f i l l i n g th e spoon, l e v e l l i n g by s c r a p in g a c r o s s th e to p o f th e spoon w ith a m e ta l s p a t u l a , f a i r l y e q u a l am ounts o f c a t a l y s t can b e m easu red o u t. T h ree s u c c e s s iv e m easu rem en ts o f c a t a l y s t H i(R )2 -5 3 made w ith a g l a s s spoon w ere ch eck ed by w e ig h in g on an a n a l y t i c a l b a la n c e .
The w e ig h ts to th e c l o s e s t m illig r a m w e re , 0 .4 0 3 g . ,
0 .4 8 5 g . and 0 .4 9 0 g« W eig h in g s o f two l e v e l s p o o n s f u l o f c a t a l y s t H i(R )2 -2 6 m e a su re d on a g l a s s spoon were 1 .1 6 g . , 1 .1 5 g . and 1 .1 4 g . These w e ig h ts a r e a s c lo s e a s a re n eed ed f o r th e e x p e r i m e n ts.
H ot a l l m easu rem ents w ere fo u n d t o be made a s c l o s e ly
b u t th e above r e s u l t s i n d i c a t e t h a t f a i r l y e q u a l am ounts o f c a t a l y s t s can be o b ta in e d . o u t w ith a g l a s s sp o o n .
A ll c a t a l y s t sam p les w ere m easu red
12
P ig . 1 R e p r o d u c ib ility o f H ydrogenation Runs H ydrogenation o f a L iq u id M ixture C on tain in g S ty re n e and E thanol in l t 2 P a r ts by Volume T o ta l Volume, 75 ml
15.0
o Run 2-39B + Run 2-40A
HTDROGB; ABSORBE) P .S .I .
10.0
5 .0
0.0
5 .0 TIME
10.0
— m in utes
13
P ig# 2 Reproduo U t i l i t y o f H ydrogenation Rune H ydrogenation o f a L iq u id M ixture C o n ta in in g S ty ren e and E than ol in l s 2 P arte by Volisae T o ta l Volume9 85 m l.
20.0
0 Run 2 -4 0 0 1 Run 2 -4 1 4
IQ.O
5 .0
0.0 0
. 0.0
5 .0 TIME —
mlnutee
14
R e p r o d u e l b l l l t y o f H y d ro g e n a tio n Runs The r e p r o d u c i b i l i t y o f th e ru n s a r e i l l u s t r a t e d by th e h y d ro g e n a tio n o f a s o l u t i o n o f s ty r e n e i n e th a n o l ( 1 :2 p a r t s by volum e) o v e r c a t a l y s t ]fi(R )2 -2 6 p r e p a re d by th e p r o c e d u re d e s c r ib e d i n P a r t IX o f t h i s t h e s i s .
Two s u c c e s s iv e h y d ro g e n a
t i o n o f 75 m l. p o r t i o n s and 85 m l. p o r t i o n s a r e shown in P i g . 1 . C a t a l y s t sa m p les w ere m easured w ith a g l a s s sp o o n . T ab le 2 (See F i g s . 1 & 2) R e p r o d u c i b i l i t y o f H y d ro g e n a tio n Runs Run
S ty r e n e - e th a n o l 1 :2 p a r t s by volum e
I n i t i a l m ix tu r e tem p.
C a ta ly s t
2-39B
75 m l.
3 1 .2 0 c .
0 .6 0 g .
2-40A 2-400 2-41A
75 85 85
3I.9OC. 31 .8 °C . 31.80c.
0 .6 9 0 .5 6 0 .5 8
R ate 1 .7 5 p s i m in. 1 .7 5 1 .7 0 1 .7 0
The E f f e c t o f T em p eratu re W ith in c e r t a i n l i m i t s , th e te m p e ra tu re o f th e r e a c t i o n m ix tu re a p p a re n tly h as l i t t l e
e f f e c t on th e m easu red h y d ro g e n a tio n
v e l o c i t y of s t y r e n e . I t i s fo u n d t h a t ev en a f t e r th e r a t e h y d ro g e n a tio n h a s r e a c h e d a c o n s ta n t v a l u e , th e te m p e r a tu re o f th e o u te r s u r f a c e o f th e r e a c t i o n f l a s k c o n tin u e s to i n c r e a s e .
T h is means t h a t
th e r a t e o f h y d r o g e n a tio n i s p r a c t i c a l l y th e same a t d i f f e r e n t m ix tu re tem perabrnes ( F ig . 3 ) . H y d ro g e n a tio n ru n s s t a r t i n g a t d i f f e r e n t I n i t i a l te m p e ra t u r e s o f e q u i v a l e n t m ix tu r e s gave a b o u t th e same r a t e .
F irs t,
f o u r b la n k r u n s w ere made u s in g 26 m l. of s ty r e n e and one l e v e l
15 P ig . 3 Hydrogen P r e ssu r e and Temperature Changes in th e H ydrogenation o f S ty ren e
40
3 5 .0
4 5 .0
30
10.0 TIME — m inutes I II
Hydrogen P ressu re-T im e Curve Tampersture-Tlme Curve
16
s p o o n fu l o f c a t a l y s t f o r e a c h .
These w ere th e n a llo w e d to c o o l
u n d e r h y d ro g en p r e s s u r e f o r d i f f e r e n t l e n g t h s o f tim e .
A fte r
l e t t i n g e a c h s ta n d f o r a d e f i n i t e p e r io d o f tim e u n d e r h y d ro g e n , a second 25 m l. p o r ti o n o f s ty r e n e was ad d ed and th e h y d ro g e n a tio n c a r r i e d o u t once more over th e same c a t a l y s t . The r a t i o
o f th e seco n d r a t e to t h a t o f th e b la n k was p r a c t i c a l l y
c o n s ta n t r e g a r d l e s s o f th e i n i t i a l te m p e r a tu re . T ao le 3 In d ep en d en ce o f H y d ro g e n a tio n V e lo c ity o f th e I n i t i a l M ix tu re T em perature Run
In itia l tem p.
R a te
39A
4 0 .0 ° 0 .
1 .9 0
B la n k ra te m in.
390 40A 420
3 7 .0 * 0 . 3 2 .0 0 . 2 8 .0 * 0 . I t a p p e a rs,
2 .0 0 . 2. .0. 0 1 .9 0
1 .2 0 £ s i m in. 11.2.255 11.2.255 1 .2 0
R a tio o f ra te s 1 .5 8 1 .6 0 1 .6 0 1 .5 8
t h e r e f o r e , t h a t r e p r o d u c ib le r e s u l t s can be
o b ta in e d in t h i s r e a c t i o n w ith o u t to o much r e g a r d to th e i n i t i a l m ix tu re te m p e r a tu r e .
17
R e s u l t s and D is c u s s io n 1 . H y d ro g e n a tio n O urvee an d th e M easure o f A c t i v i t y . T y p ic a l fo rm s o f th e h y d r o g e n a tio n c u r v e s f o r s t y r e n e s t a r t i n g o f f a t 45 p . s . i . gauge p r e s s u r e of h y d ro g en I n th e P a r r lo w - p r e s s u r e s h a k in g a p p a r a tu s I s shown I n P i g . 4 .
The
r e a c t i o n may b e g in a t a r e l a t i v e l y h ig h i n i t i a l r a t e an d q u ic k ly r e a c h a c o n s t a n t r a t e o f h y d ro g e n a tio n (c u rv e A ), o r i t may s t a r t o u t a t a lo w e r r a t e an d g r a d u a lly b u i l d r a t e ( c u rv e B ).
up to a c o n s ta n t
I n b o th o a s e s , th e h y d r o g e n a tio n v e l o c i t y
re m a in s a p p ro x im a te ly c o n s t a n t , th e n c h a n g e s a b r u p tly when s a tu r a tio n i s reach ed .
I f s u f f i c i e n t s ty r e n e i s p r e s e n t ,
h o w ev er, th e v e l o c i t y d im in is h e s m ore o r l e s s r a p i d ly a s th e h y d ro g en p r e s s u r e g o e s down (c u rv e 0 ) .
The s u p p ly o f hydrogen
i s p ro b a b ly th e e f f e c t i v e f a c t o r in c o n t r o l l i n g th e r e a c t i o n v e l o c i t y a t t h i s s t a g e , s in c e when th e h y d ro g en p r e s s u r e i s i n c r e a s e d t h e h y d ro g e n a tio n p r o c e e d s a t a c o n s ta n t r a t e a s b e fo re (se e P ig . 6 ).
The r e a c t i o n v e l o c i t y i s f o r t h e m ost
p a r t in d e p e n d e n t o f t h e s u p p ly o f s t y r e n e . The s lo p e o f th e s t r a i g h t l i n e p o r ti o n i s g e n e r a ll y u sed a s th e m easu re o f c a t a l y t i c a c t i v i t y .
T hese a r e more
r e p r o d u c ib le th a n th e tim e r e q u i r e d f o r c o m p le tin g th e re a c tio n .
Som etim es, when m aking c o m p a riso n s , i t i s n e c e s s a r y
to ta k e i n t o a c c o u n t th e r a p i d i t y w ith w h ich t h e maximum c o n s t a n t r a t e i s r e a c h e d b e c a u s e o f o n ly a s l i g h t d i f f e r e n c e i n th e s l o p e s . in P ig . 4 .
An exam ple w ould be th e two c u r v e s , A and B,
G e n e r a lly , t h e more a c t i v e c a t a l y s t r e a c h e s th e
18
P ig . 4
The Shapes o f H ydrogenation Curves
TIME
19
Fig* 3
E f f e o t o f R e s to r in g Hydrogen to I t s I n i t i a l P r e ssu r e
20*0 Hydrogen P r essu re p .B * i*
5 0.0 P r essu re
\
3 5 .0
4 0 .0
4 5 .0
20
10 Time —
minutes
20
maximum e a r l i e r , and g i v e s a f a s t e r tim e o f c o m p le tio n . 8 . E f f e c t o f l i q u i d T olum e. The r a t e o f hydrogen g a s a b s o r p tio n i n th e l i q u i d p h a se h y d r o g e n a tio n o f s t y r e n e o v e r f r e s h l y p r e p a r ed Haney n i c k e l c a t a l y s t i n a P a r r lo w -p r e s s u r e sh a k in g a p p a ra tu s v a r i e s w it h th e t o t a l l i q u i d v o lu m e, a l l o th e r f a c t o r s b e in g e q u a l.
The
t o t a l l i q u i d may b e s t y r e n e a lo n e o r s t y r e n e w it h a s o l v e n t s u c h a s an a l c o h o l , k e to n e o r h y d ro ca rb o n .
U sin g a b o u t th e
same amount o f c a t a l y s t i n e a c h c a s e , th e r a t e a t f i r s t i n c r e a s e s w it h l i q u i d volum e up to some maximum, a lth o u g h th e r a t i o o f th e c a t a l y s t w e ig h t to hyd rogen a c c e p t o r i s d e c r e a s in g .
I t a p p ea r s
t h a t l i q u i d v o lu m e, q u it e a p a r t from w hat i s u s u a l l y c a l l e d a ■ s o lv e n t e f f e c t * i s an i n d i r e c t f a c t o r in th e h y d r o g e n a tio n o f s t y r e n e o v e r Raney n i c k e l c a t a l y s t . From r e s u l t s w h ich w i l l b e d is c u s s e d l a t e r ,
i t a p p ea r s
more p r o b a b le t h a t i n t e r f a c e b etw een th e g a s and l i q u i d p h a se s i s th e r e a l d e te r m in in g f a c t o r , o f th e l i q u i d v o lu m e.
t h i s b e in g in p a r t a f u n c t io n
U n f o r t u n a t e ly , t h i s i n t e r f a c i a l a r e a i s
n o t e a s i l y d e te r m in a b le so t h a t t h i s f a c t o r h a s t o b e e x p r e s s e d in a d e q u a te ly in term s o f th e l i q u i d v o lu m e. The ch an ge in h y d r o g e n a tio n v e l o c i t y w it h d i f f e r e n t v olu m es o f s t y r e n e , o t h e r f a c t o r s b e in g e q u a l, i s d em o n stra ted in F i g . 6 .
The e f f e c t o f in c r e a s in g am ounts o f e th y lb e n z e n e and
o f e t h a n o l on th e h y d r o g e n a tio n r a t e o f 25 m l. o f s ty r e n e a r e shown in F i g s . 7 and 8 , r e s p e c t i v e l y .
The in c r e a s e in r a t e in
t h e s e c a s e s o v er t h a t o f 25 m l. o f s t y r e n e h y d r o g e n a te d w it h -
21
Fig* 6
i n Hydrogen&tlon R ate w ith Volume o f S ty ren e
RATE B 4sl min*
1.00
25
50
75
Volume o f S ty ren e
100 ml*
125
22
F ig .7
The E f f e c t o f E th y lb e n z e n e on th e H y d ro g en a tio n R ate o f S ty r e n e
3 .0 0
RATE
p.s.i min.
2 .0 0 25
50
75
100
125
Volume o f E th y lb en ze n e Added t o 2 5 m l. o f S ty r e n e — m l.
33
P ig . 8
E f f e c t Of E thanol on th e H ydrogenation Rate o f S tyren e
2 .5 0
2.00 RATE
1.00
0 .5 0
0
25
50
75
100
V olim e o f E th anol Added t o 25 m l. o f S tyren e - - m i l l i t e r s
24
o u t s o l v e n t c a n n o t be a t t r i b u t e d e n t i r e l y t o a ^ s o l v e n t ” e f f e c t In Ylew o f th e r e s u l t s o b ta in e d w ith s ty r e n e a l o n e . I n P i g . 9 , th e r a t e s f o r h y d r o g e n a tin g d i f f e r e n t am ounts o f a s t y r e n e - e t b a n o l s o l u t i o n ( 1 :2 p a r t s by volum e) a r e p l o t t e d a g a i n s t t o t a l l i q u i d vo lum e.
The d i f f e r e n t c u r v e s w ere o b ta in e d
w ith th e same c a t a l y s t b u t a t d i f f e r e n t a g e s .
I t i s seen th a t
a s th e c a t a l y s t d e c r e a s e d in a c t i v i t y due to a g in g , th e change i n r a t e w ith volum e on th e a s c e n d in g p o r t i o n o f th e c u rv e d e c r e a s e d u n t i l f i n a l l y th e volume e f f e c t seem s t o have d is a p p e a r e d a f t e r 4 m o n th s. The sh ap e o f th e r a t e - l i q u i d volume c u rv e p a s t th e maximum is n o t a t a l l c le a r.
R e s u lts so f a r seem t o i n d i c a t e a d ip
j u s t p a s t th e maximum. 8 . E f f e c t o f th e Amount o f C a t a l y s t * The r a t e o f h y d ro g e n a tio n o f s ty r e n e i s n o t p r o p o r t i o n a l to th e am ount o f c a t a l y s t u s e d .
T h is i s i l l u s t r a t e d i n P ig s . 10
and 11 w here r a t e s o b ta in e d w ith one l e v e l s p o o n fu l o f c a t a l y s t a r e com pared w i t h th o s e o b ta in e d w ith tw ic e t h a t amount o f c a ta ly s t.
I n P i g . 1 0 , s ty r e n e i s u s e d w ith o u t a s o lv e n t , in
P i g . 11 a s t y r e n e - e t h a n o l s o lu t i o n ( 1 :2 p a r t s by volum e) i s used.
I t s h o u ld be o b s e rv e d t h a t to w a rd th e lo w e r volum es th e
r a t e becom es l e s s s e n s i t i v e to c h an g es i n th e am ounts o f c a t a l y s t an d e r r o r s i n m e a su rin g th e q u a n t i t y o f c a t a l y s t become l e s s im p o r ta n t. D a ta f o r P i g . 11 a r e g iv e n in T able 4 .
F ig , 9
E f f e c t o f Age on C a t a l y s t
2.50
R ate p .8 .1 . m ln . 2.00
1.50
II
1.00
100
50
T o ta l Volume - - m l. I Age o f c a t a l y s t , one week. I I F our weeks I I I Four m onths
26
Fig* 10 E f f e c t o f th e Amount o f C a t a l y s t on th e H y d ro g e n a tio n R ate
2 .5 0 Rate 2.00
• 1. mln. 1 .5 0
1.00
0 .5 0
100
125
Volume o f S ty re n e — m l. U pper c u rv e o b ta in e d w ith tw ic e th e am ount o f c a t a l y s t u sed f o r th e lo w e r c u rv e .
27
P lg # ll
E f f e c t o f the Amount o f C a t a ly s t on th e H ydrogenation Rate
Rate
3.00
p . 8.1 m ln.
2.50
II
2.00
1 .5 0
1.00 50
75
100
125
T o ta l Volume m l. L iq u id m ixture o f s ty r e n e and e th a n o l In 1 :2 p a r ts by volum e. Upper curve o b ta in ed w ith tw ic e th e amount o f c a t a l y s t used fo r th e lo w er c u r v e .
28
fable 4 B f f e o t o f L iq u id Volume an d C a t a l y s t Amount on th e B a te tun n o .
S ty r e n e - e th a n o l ( l; 2 v o l. p a rts )
C a ta ly s t*
R a te
2-41B
60 m l.
0 .6 9 g .
1 .2 0 m in .
2-40B 2-59B 2-40A 2-400 2-41A 2-42A 2-43A E-42B
60 75 75 86 86 100 110 125
0 .5 4 0 .6 0 0 .5 9 0 .6 6 0 .5 8 0 .6 0 0 .6 3 0 .6 8
1 .5 0 1 .7 6 1 .7 5 1 .7 0 1 .7 0 1 .3 5 1 .4 5 1 .4 5
2-39A 2-36A 2-37B 2-37A 2 —36B
60 76 86 100 125
1 .1 2 1 .1 5 1 .1 6 1 .1 4 1 .1 6
2 .0 0 2 .5 0 2 .9 0 2 .8 6 2 .8 0
O a t a l y s t l i ( R ) 2 - 2 6 , ag e 3 -4 w eek s. 4* S u g g e s te d P ro c é d u re f o r C a t a l y s t T e s tin g . S in c e th e h y d ro g e n a tio n o f s ty r e n e i s s u b j e c t to a l i q u i d volum e e f f e c t , i t i s n e c e s s a r y to ta k e t h i s in to c o n s id e r a tio n when co m p arin g d i f f e r e n t c a t a l y s t p r e p a r a t i o n s .
A s in g le
h y d ro g e n a tio n w ith e a c h u s in g an a r b i t r a r i l y s e l e c t e d am ount o f s t y r e n e a n d s o lv e n t may n o t g iv e th e p r o p e r p i c t u r e ( s e e P ig . 1 2 ). fh e f o ll o w i n g p ro c e d u re i s s u g g e s te d .
E q u a l am ounts o f a
c a t a l y s t a r e u s e d in th e h y d ro g e n a tio n o f a l i q u i d m ix tu re o f c o n s ta n t c o m p o s itio n , s a y 1 :2 p a r t s by volum e o f s ty r e n e in e th a n o l.
Enough s o l u t i o n i s p r e p a re d so t h a t r u n s c a n b e made
w ith 50 m l ., 60 m l ., 75 m l ., and 86 m l. w ith e a c h c a t a l y s t . P o t o n ly t h e m easu red h y d r o g e n a tio n v e l o c i t i e s b u t a l s o th e
29
Pig.
12
Comparison o f Two Raney N ic k e l P r ep a ra tio n s
2 .0 0 RATE II
P . s #1. m ln.
I C a ta ly s t N 1(R )1-73 I I C a ta ly s t N 1(R )2-10
1 .5 0
50
75
Volume o f Ethanol Added to 25 m l. o f S tyren e — m i l l i t e r s
100
30
s lo p e o f th e a s o e n d ln g p o r t i o n o f th e r a t e - * l i q u l d voltm ie o n rv e may he u s e d f o r c o m p a riso n .
A c tu a lly , t h i s was th e m ethod u s e d
i n show ing th e d e c r e a s e i n a c t i v i t y o f a c a t a l y s t w ith age ( f i g . 9 ) . The s lo p e d e c r e a s e d a s th e a c t i v i t y w en t down,
fre s h c a ta ly s ts
a r e c h a r a c t e r i s e d hy s te e p s lo p e s in t h i s t e s t . I n f i g . 1 3 , t e s t s o f two c a t a l y s t h a t c h e s p r e p a r e d hy two d i f f e r e n t p ro c e d u re s a r e i l l u s t r a t e d . week a f t e r p r e p a r a t i o n . o th e r i s d e a r l y
The t e s t s w ere made a
The s l i g h t s u p e r i o r i t y o f one o v e r th e
shown.
P ro c e d u re and a p p a r a tu s f o r c a r r y in g o u t t h e h y d ro g e n a tio n w ere d e s c r i b e d e a r l i e r . Summary A p p a ra tu s a n d p ro c e d u re i n c a r r y i n g o u t th e h y d ro g e n a tio n w ere d e s c r i h e d .
f a c t o r s i n f l u e n c in g th e h y d ro g e n a tio n o f
s ty r e n e o v e r Raney n i c k e l o a t a l y s t w ere d is c u s s e d .
The h y d ro -
g e n a tio h o f s ty r e n e i s s u b j e c t to l i q u i d volum e e f f e c t .
The
r a t e i s n o t a lw a y s p r o p o r t i o n a l to t h e am ount o f c a t a l y s t . p ro c e d u re f o r t e s t i n g c a t a l y t i c a c t i v i t y i s p r e s e n te d .
A
31
P ig . 13 ACTIVITY TESTS Comparison o f Two D if f e r e n t C a ta ly s ts
2 .5 0 RATE
I II
c a t a l y s t N i(R )2 -5 3 C a ta ly s t N i(R )2-26
1 .5 0 50
75 T o ta l L iq u id Volume — ml#
100
32
PART II THE PREPARATION OP RANEY NICKEL CATALYST AND SOÎŒ FACTORS INFLUENCING THE ACTIVITY OP THE OATALYST I n t r o lu o t lo n The b la c k to g r a y -b la c k r e s id u e o b ta in e d by d e c o m p o s itio n o f n ic k e l-a lu m ln u m a l l o y w ith c a u s t i c a l k a l i s o l u t i o n c o n s t i t u t e s w hat i s c a l l e d ^Raney n i c k e l # ”
The method o f le a c h in g
h a s a b e a r in g on th e a c t i v i t y o f the r e s u l t a n t c a t a l y s t .
The
o r i g i n a l p ro ced u re g iv e n by Raney (3 6 ) h a s b een m o d ifie d by l a t e r i n v e s t i g a t o r s to p rod u ce more a c t i v e c a t a l y s t s ( 2 , 3 , 6 , 2 9 ) . B e c a u se o f th e la c k o f u n ifo r m ity in a c t i v i t y o f c a t a l y s t s p r e p a r e d by d i f f e r e n t p r o c e d u r e s o f le a c h in g and w a sh in g , th e term ”Raney n i c k e l ” i s becom ing more and more a g e n e r a l term . A d k in s and P a v l ic (3 ) have in tr o d u c e d a W-number sy ste m t o d e s ig n a t e c e r t a i n c a t a l y s t s p rep a red by c e r t a i n sta n d a r d p roced u res. The a c t i v i t y
o f th e o a t a l y s t d o e s n o t seem to b e much
in f lu e n c e d by th e c o m p o s itio n o f th e i n i t i a l a l l o y .
Raney
(3 6 ) c la im s e f f i c i e n t r e s u l t s w it h n io k el-a lu m in u m a l l o y s c o n t a in in g 10 to 85 p e r c e n t n i c k e l and 90 to 15 p e r c e n t aluminum, r e s p e c t i v e l y .
Dupont and P i g a n io l (1 1 ) say t h a t 30
to 50 p e r c e n t N i a l l o y s a r e b e s t .
Any a l l o y c o n t a in in g l e s s
th an 52 p e r c e n t N i c a n be u se d ; above t h i s , p a r t o f th e n i c k e l i s p r e s e n t i n th e form o f th e N iA l, w h ic h i s n o t a t t a c k e d by a lk a li. The e x t e n t o f le a c h in g recommended v a r i e s from v ery s l i g h t
33
t o a s o o m p le te ly p o s s i b l e .
I t i s n o t c l e a r how much o f th e
aluminum m u st be rem oved to g iv e a o a t a l y s t o f maximum a c tiv ity
(3 7 ).
A t any r a t e , a c e r t a i n amount o f alum inum,
v a r y in g from 1 to 17 p e r c e n t , a lw a y s rem a in s w it h th e o a t a l y s t , t h i s com ponent b e in g i n a form n o t a t t a c k e d by a l k a l i ( 3 2 ) . Som etim es o n ly a p o r t io n o f th e aluminum i s removed th ro u g h u s e o f a s m a lle r q u a n tit y o f sodium h y d r o x id e .
Such a c a t a l y s t
can b e r e a c t i v a t e d by f u r t h e r tr e a tm e n t w it h a l k a l i when i t lo s e s i t s a c t i v i t y ( 1 ,1 9 ) . T here i s no agreem en t among th e d i f f e r e n t i n v e s t i g a t o r s on th e te m p e r a tu r e o f a d d it io n o f th e a l l o y to th e a l k a l i s o l u t i o n o r on th e le n g t h and tem p era tu re o f th e d i g e s t i o n p e r io d a f t e r a l l th e a l l o y h a s b e e n add ed . A c o n s id e r a b le amount o f hydrogen i s l i b e r a t e d i n th e le a c h in g p r o c e s s and some o f th e hydrogen i s r e t a in e d by th e o a t a ly s t r e s id u e .
The p r e s e n c e o f h yd rogen seem i n d i s p e n s i b l e
to th e a c t i v i t y o f th e c a t a l y s t ( 3 2 ) .
The amount o f hydrogen
r e t a i n e d by th e o a t a l y s t under d i f f e r e n t te m p er a tu r e s o f l e a c h in g a r e a s f o ll o w s : T em perature o f l e a c h in g , d e g r e e Q.
m l. o f hydrogen r e t a in e d p e r g . c a t a l y s t
50 60 100
470 1 6 0 -1 7 0 140
R e fe r e n c e ___________ ( 30) (SO) ( 5)
The te m p er a tu r e u se d f o r d i g e s t i o n in th e p r o c e d u r e s g iv e n by P a v l i c and A d k in s (3 3 ) f o r th e p r e p a r a tio n W-3 and W-4 c a t a l y s t s , by A d k in s and B i l l i c a
(2 ) f o r th e p r e p a r a tio n o f W-5, W-6 and
W-7 c a t a l y s t s i s 5 0 ® 0 ., w h ich c o r r e sp o n d s to a tem p era tu re o f
34
h ig h h yd rogen r e t e n t i o n . I n c e r t a i n p r o c e d u r e s f o r c a t a l y s t p r e p a r a tio n , hyd rogen from an e x t e r n a l s o u r c e i s a l s o u s e d .
Raney (3 6 o ) c la im s t h a t
th e o fita ly tio p r o p e r t ie s o f th e m a t e r ia l o b ta in e d a f t e r le a c h in g th e a l l o y and s u b s t a n t i a l l y w a sh in g i t f r e e from a l k a l i , may b e en h an ced by tr e a tm e n t w it h hydrogen g a s , under s u i t a b l e c o n d it io n s o f tem p era tu re and p r e s s u r e .
The p r e p a r a tio n o f
th e W-6 Raney n i c k e l , w h ich i s c o n s id e r e d to be th e m ost a c t i v e n i c k e l known a t th e p r e s e n t ( 2 , 2 4 ) , in c lu d e s a s t e p w h ich c o n s i s t s in w a sh in g th e c a t a l y s t under p r e s s u r e o f h y d ro g e n . The u s e o f hydrogen un der p r e s s u r e in th e w a sh in g s te p may be a d v a n ta g e o u s in t h a t i t p r o t e c t s th e c a t a l y s t from c o n t a c t w ith a i r and th e l o s s o f th e l a r g e q u a n tit y o f hyd rogen w hich i s a d so rb ed on th e c a t a l y s t s u r f a c e ( 2 ) .
The a c t i v i t y o f Raney
c a t a l y s t s d e c l i n e s a s th e hyd rogen a b so rb ed by th e m e ta l i s l o s t b u t th e two b e h a v io r s a r e n o t p a r a l l e l ( 3 7 ) .
Some o f th e
work d e s c r ib e d i n t h i s t h e s i s i n d i c a t e s t h a t th e a c t i v i t y o f th e o a t a l y s t ca n be r e t a i n e d by s t o r a g e under h y d ro g en . The p r e p a r a tio n o f the o a t a l y s t d e s c r ib e d h e r e was worked o u t in d e p e n d e n tly b e f o r e th e p r e p a r a tio n o f W-^7 c a t a l y s t d e s c r ib e d by A dk ins and B i l l i c a
(2) was n o t i c e d .
There i s a
s i m i l a r i t y i n th e p r o c e d u r e s . P r o c e d u r e s f o r t h e p r e p a r a tio n o f Raney n i c k e l o a t a l y s t u s u a ll y c a l l f o r e x t e n s i v e w ash in g w ith w a te r to rem ove a s u b s t a n t i a l p o r t io n o f th e a l k a l i and s a l t from th e n i c k e l r e s id u e .
F or i n s t a n c e , in th e p ro ced u re g iv e n by P a v lic and
35
A d k in s ( 3 3 ) , c a t a l y s t p r e p a r ed from 100 g . o f Raney n i c k e l a l l o y i s w ash ed w ith ab ou t 15 l i t e r s o f w a te r (tw o to th r e e h o u rs) o r u n t i l th e wash w a te r t e s t s n e u t r a l to l i t m u s ,
A s u ita b le
c a t a l y s t f o r h y d r o g e n a tio n may be p rep a red even i f t h i s l a s t w a sh in g tim e
s t e p i s o m it te d .
T h is p e r m its c o n s id e r a b le s a v in g o f
in b a tc h p r e p a r a tio n o f c a t a l y s t . A dk ins and B i l l i c a
say t h a t th e W-7 c a t a l y s t i s a t t r a c t i v e
b e c a u s e o f th e s i m p l i c i t y o f th e p r o c ed u r e u se d in w a sh in g i t . T h eir p ro ced u re i s a s f o ll o w s : The p r o c ed u r e u se d in th e p r e p a r a tio n o f W-7 Raney n i c k e l , a f t e r th e d i g e s t i o n and th e th r e e d é c a n t a t io n s , i s to t r a n s f e r th e c a t a l y s t to a 250 m l. c e n t r if u g e b o t t l e w ith 95 p e r c e n t a lc o h o l. I t i s th en w ashed th r e e tim e s by s t i r r i n g , n o t s h a k in g , w ith 150 m l. o f 95 p e r c e n t e t h a n o l, c e n t r i f u g i n g a f t e r e a ch a d d i t io n . In th e same manner, th e c a t a l y s t i s w ashed th r e e tim e s w it h a b s o lu t e e t h a n o l. A lth o u g h W-6 i s c o n s id e r e d th e m ost a c t i v e c a t a l y s t , th e W-7 o a t a l y s t was more a c t i v e th an W-6 w ith o u t t r ie t h y la m in e tow ard a c e to p h e n o n e .
The o a t a l y s t gave co m p lete h y d r o g e n a tio n
o f hydro q u in one in 15 m in u te s a s a g a in s t th e e ig h t h ou rs r e q u ir e d by W -6.
Such a o a t a l y s t i s , t h e r e f o r e , n o t w ith o u t
i t s s p e c i a l a d v a n ta g e s . E x p e r im e n ta l P roced u re.
In a t w o - l i t e r E rlen m eyer f l a s k , eq u ip p ed w it h a
therm om eter and a H ersh b erg s t i r r e r , i s p la c e d a s o l u t i o n o f 160 g . o f sodium h y d r o x id e in 60 m l. o f d i s t i l l e d w a te r . f l a s k i s k e p t in an i c e b a t h . Raney n ic k e l-a lu m in u m a l l o y
The
One hundred tw enty grams o f
i s added i n s m a ll p o r t io n s o v e r a
56
p e r io d o f a b o u t t h i r t y m in u tes# i s k e p t a t a b o u t 60 to 66 OG.
The te m p er a tu r e o f th e m ix tu r e
A fte r a d d it io n o f a l l th e a l l o y ,
t h e s u s p e n s io n i s d ig e s t e d a t t h i s te m p er a tu r e f o r f i f t y m in u te s w it h g e n t le s t i r r i n g *
The f l a s k c o n t a in in g th e m ix tu r e
i s th e n rem oved from th e s e t - u p , f lu s h e d w it h hyd rogen from a ta n k s o u r c e , sto p p e r e d and th e m ix tu r e a llo w e d t o c o o l to room te m p er a tu r e by s t a n d in g .
The o a t a l y s t i s th en w ashed fo u r
t im e s by d é c a n t a t io n w ith d i s t i l l e d w a te r , t w ic e w it h 96 p e r c e n t e th a n o l and two tim e s w it h com m ercial a b s o lu t e e th a n o l and s t o r e d under e t h a n o l. A c tiv ity T e st.
The a c t i v i t y
o f the b a tc h , ( N i( R ) 2 - 2 6 ) , p r e p a r ed
by th e ab ove p ro ced u re w as t e s t e d by h y d r o g e n a tin g a 1 :2 volum e r a t i o s o l u t i o n o f s ty r e n e in e th a n o l in th e manner d e s c r ib e d e a r lie r , i . e . ,
e q u a l am ounts o f th e o a t a l y s t w ere u se d in th e
h y d r o g e n a tio n o f d i f f e r e n t vo lu m es o f th e above l i q u i d m ix tu r e (s e e F ig . 1 3 ).
A b a tc h , N i(R )2 - 5 3 , p rep a red by a s l i g h t
m o d if ic a t io n o f th e p ro ced u re f o r W-4 c a t a l y s t p r e p a r a tio n g iv e n by P a v l ic and A dk ins (3 3 ) a c tiv ity .
showed a s l i g h t l y h ig h e r
N e v e r t h e le s s , c a t a l y s t p rep a red by th e above p ro ced u re
may b e c o n s id e r e d v e r y a c t i v e . M ost o f th e W-4 p r e p a r a tio n s gave h y d r o g e n a tio n cu rv e s im i l a r t o c u r v e B in F i g . 4 .
H y d rogen ation c u r v e s f o r
N i(R )2 -2 6 p r ep a red by th e ab ove p ro ced u re showed h ig h i n i t i a l r a t e o f r e a c t io n and c o r r e sp o n d e d to c u rv e A.
I t w as a t f i r s t
th o u g h t t h a t t h i s was a c h a r a c t e r i s t i c o f t h i s o a t a l y s t . H owever, a W-4 c a t a l y s t p r ep a red by a s l i g h t m o d if ic a t io n o f th e P a v l ic and A d k in s p ro ced u re gave
h y d r o g e n a tio n c u r v e s
37
o o r r e s p o n d in g to c u r v e A.
Curve A i s p r o b a b ly c h a r a c t e r i s t i c
o f any v e r y a c t i v e Raney n i c k e l c a t a l y s t r e g a r d le s s o f p r e p a r a t iv e p r o c e d u r e . The W-7 o a t a l y s t i s r e f e r r e d to a s an a l k a l i n e o a t a l y s t g i v i n g good r e s u l t s in h y d r o g e n a tin g k e t o n e s , p h e n o ls and n itr ile s .
The a l k a l i in th e r e a c t io n m ix tu r e i s c o n s id e r e d
b e n e fic ia l.
The a lc o h o l under w hich c a t a l y s t N i(R )2 -2 6 was
s t o r e d d id n o t g iv e an a l k a l i n e r e a c t io n w it h p h e n o lp h t h a le in . The e v a p o r a tio n o f th e a lc o h o l l e f t a w h ite r e s id u e . R e a c t i v a t io n .
I t i s p o s s ib le
to r e a c t i v a t e Raney n i c k e l
c a t a l y s t s w h ich h a s l o s t some o f i t s a c t i v i t y due to a g e o r t o u s e i n p u r i f i c a t i o n o f o r g a n ic l i q u i d s by th e f o ll o w i n g s im p le and c o n v e n ie n t p r o c e d u r e .
F i f t y grams o f th e Raney n i c k e l
c a t a l y s t to be r e a c t i v a t e d i s added to 50 m l. o f 20 p e r c e n t aqu eou s NaOH s o l u t i o n and h e a te d a t 60 to 65^ 0. f o r te n m in u te s in an E rlen m eyer f l a s k .
The f l a s k i s s to p p e r e d and
th e m ix tu r e a llo w e d to c o o l to room tem p era tu re by s ta n d in g . The o a t a l y s t i s w ashed f o u r tim e s by d é c a n ta t io n w ith d i s t i l l e d w a te r , th en fo u r tim e s w ith th e o r g a n ic l i q u i d in w h ich i t i s t o be k e p t . R e a c t iv a t io n e x p e r im e n ts . c a ta ly s t.
I t i s s to r e d under l i q u i d a s u s u a l . O a ta ly s t N i(R )2 -1 0 was a W-4
The age o f th e sam ple was a b o u t two m on th s.
C a t a ly s t N i(R )2 -1 0 R w as p rep a red by r e a c t i v a t i o n o f N i(R )2 -1 0 by th e p r o c ed u r e g iv e n a b o v e .
The r e a c t i v a t e d c a t a l y s t u sed
i n th e h y d r o g e n a tio n o f 25 m l. o f s ty r e n e i n d i f f e r e n t v o lu m es o f e t h a n o l g a v e a s l i g h ü y h ig h e r r a t e o f r e a c t io n than th e o r ig in a l c a t a ly s t .
M oreover, th e c h a r a c te r o f h y d r o g e n a tio n
38
c u r v e ch an ged from one c o r r e s p o n d in g to c u rv e B , P ig * 4 , to one s i m i l a r to cu rv e A ( s e e P ig * 1 4 ) . A s im i l a r *^hefore and a f t e r " tr e a tm e n t i s i l l u s t r a t e d in P i g . 15 in w h ich th e o r i g i n a l c a t a l y s t w as once u s e d in p u r i f i c a t i o n o f d io x a n hy r e f l u r i n g and t h e r e f o r e s u b j e c t e d to te m p e r a tu r e in th e n eig h b o rh o o d o f 100®0. R e s u l t s and D is c u s s io n The E f f e c t o f Hydrogen on C a t a ly s t P r e p a r a t io n s . Some o f th e b e n e f i c i a l e f f e c t w h ich i s c la im e d f o r th e u s e o f hyd rogen was m e n tio n e d e a r l i e r in th e in t r o d u c t io n t o t h i s p a r t.
P a t t i s o n (3 1 ) s t u d ie d th e e f f e c t o f n it r o g e n g a s , a i r ,
and oxygen g a s on Haney n i c k e l in s t o r a g e and h a s fo u n d th e r e t a r d in g e f f e c t o f t h e s e g a s e s on th e o a t a l y s t a c t i v i t y in c r e a s e i n t h a t o r d e r .
to
Raney n i c k e l c o n t a in s hydrogen bound
to th e m e ta l in some form w h ich i s l o s t s lo w ly in s to r a g e o f th e c a t a l y s t .
T h is l o s s i s e s p e c i a l l y r a p id i n th e p r e s e n c e
o f a ir (3 7 ). The f o l l o w i n g e x p e r im e n t was run to t e s t th e e f f e c t o f hydrogen on t h e s t o r a g e o f Raney n i c k e l .
Two c a t a l y s t sa m p les
w h ich gave th e same b la n k s in th e hyd rem an ation o f 25 m l. o f s t y r e n e w ere u s e d f o r t h i s t e s t .
A f t e r th e c o m p le tio n o f th e
r e a c t i o n , th e r e a c t i o n f l a s k s w ere rem oved from th e sh a k in g a p p a r a tu s .
One was s to p p e r e d i n a i r and th e o th e r was f lu s h e d
w ith h yd rogen and th en s to p p e r e d .
A f t e r f i v e d a y s, 25 m l. o f
s ty r e n e w as added to e a c h and h y d ro g e n a ted o v e r th e same samplei o f c a t a l y s t w h ic h had b een u s e d on ce b e f o r e . shown i n P i g . 1 6 .
The r e s u l t s a r e
39
F ig . 14
R o a o tlv a tio n o f a C a ^ ly s t
HYDROGEN ABSORBED p .8 .1 . IS.O
10.0
5 .0 I II
B efore R e a c t lv a t lo i A fte r R e a c tiv a tio n
0.00 10 TIME —
minutes
40
F ig . 15 R e a c tiv a tio n o fa C a ta ly s t
10.0
p .8 •1 •
II
5 .0
I II
B efo re R e a c t iv a t io n A f t e r R e a c t i v a t io n
0
10
15
TIME — m in u te s
20
41
Fig* 16 K eeping Q u a lity o f C a t a ly s t In a L lq u id under Hydrogen
1 5 .0 HYDROGEN ABSORBED p .8 .1 . B lank Runs 1 6 A -I, 1 6C -I -
10.0
/ '>
— Run 19B—I I ( s t o r e d under h yd rogen )
5 .0
0.00
5
10 TIME — m in u te s
15
20
42
The k e e p in g q u a l i t y o f Raney n i c k e l o a t a l y s t i n i l i q u i d u n d er an a tm osp h ere o f hydrogen i s a p p a r e n tly b e t t e r th an in l i q u i d u n d er a i r .
In v ie w o f th e l i q u i d volum e e f f e c t and
" s o lv e n t" e f f e c t o f th e e th y lb e n z e n e p r e s e n t in th e b e g in n in g o f th e sec o n d run o t e r th e same c a t a l y s t ,
even th ou gh th e
se c o n d run made w ith th e c a t a l y s t k e p t un der hydrogen atm osp h ere p r a c t i c a l l y m a tch es th e b la n k r u n s , th e a c t i v i t y
of
th e o a t a l y s t in t h i s c a s e m ust be c o n s id e r e d to have d e c r e a s e d . A c t i v i t y o f th e c a t a l y s t i s b e t t e r m a in ta in e d i n l i q u i d u n d er hyd rogen p r e s s u r e o f a few a tm o sp h e r e s.
The h y d r o g e n a tio n
cu r v e o f a s o l u t i o n o f 25 m l. s t y r e n e and 26 m l. e th y lb e n z e n e o v e r one l e v e l s p o o n fu l ( c a . 0 .9 g . m o is t w e ig h t) i s shown a s I in P ig . 17.
A f t e r th e c o m p le tio n o f t h e r e a c t i o n th e p r o d u c t
w as k e p t un der hydrogen a t 36 p . s . i . gauge p r e s s u r e f o r 15 h r s . A t th e en d o f th e p e r io d , 26 m l. o f th e l i q u i d (e th y lb e n z e n e ) was w ith draw n and 25 m l. o f s t y r e n e added and h y d ro g en a ted o v e r th e same c a t a l y s t sam p le.
The h y d r o g e n a tio n c u r v e r e a c h e d
th e same mazimum s lo p e b u t w as s lo w e r in r e a c h in g i t
(Curve I I ,
P ig . 1 7 ). B f f e o t o f a C om bination o f Tem perature Change and Hydrogen on th e A c t i v i t y o f th e g a t a l y s i . « When 25 m l. o f s ty r e n e i s h y d ro g e n a ted o v e r Raney n i c k e l , th e r e a c t i o n i s e x o th e r m ic and th e tem p era tu re o f th e m ix tu r e may go ab ove 60®C.
I f im m ed ia te ly a f t e r c o m p le tio n o f th e
r e a c t i o n , th e f l a s k c o n t a in in g th e p r o d u c t i s c o o le d under r u n n in g w a te r to room tem p era tu re and 25 m l. more o f s ty r e n e added and h y d r o g e n a tio n s t a r t e d o n ce more o v e r th e same sam ple
45
P i g . 17
K eeping Q ttality o f C a t a ly s t l a d L iq u id under Hydrogen P r essu re
20.0 H y d ro g e n A b so rb e d p . 8 .1
1 5 .0
10.0
5 .0
I II
B la n k r u n S t o r e u n d e r h y d ro g e n p r e s s u r e (3 6 p . s . i . ) f o r 15 h r s .
0 5
10
Time —
15
minutes
20
44
o f c a ta ly s t*
th e r e a c t i o n s t a r t s o f f a b o u t t h e same a s b e f o r e
b u t th e r a t e
In c re a se s s lig h tly
to w a rd th e en d (P ig * 1 8 ) .
I f , h o w e v e r, t h e m ix tu r e a f t e r c o m p le tio n o f t h e f i r s t r u n i s a llo w e d t o come down t o room te m p e r a t u r e g r a d u a l l y u n d e r an a tm o s p h e re o f h y d ro g e n , a m uch h i g h e r r a t e o r h y d r o g e n a tio n i s o b t a i n e d i n th e s e c o n d r u n ( P i g . 1 9 ) .
T h is i s p r o b a b ly n o t due
t o a n y a c t i v a t i n g e f f e c t o f t h e h y d ro g e n b u t to i t s p r o t e c t i o n o f t h e o a t a l y s t fro m e x p o s u r e to a i r w h ile i t i s s t i l l h o t . S h is c a n b e shown b y m a k in g u p a n d h y d r o g e n a ti n g a m ix tu r e c o n t a i n i n g e t h y l b e n z e n e , s t y r e n e a n d o a t a l y s t i n th e same a m o u n ts p r e s e n t a s i n t h e a b o v e m i x t u r e u s e d i n th e s e c o n d r u n . A b o u t t h e same r a t e i s o b t a i n e d ( s e e P i g . 7 ) . I n t h e p r e p a r a t i o n o f W-4 c a t a l y s t g iv e n b y P a v l i c an d A d k in s , t h e o a t a l y s t i s d i g e s t e d a t 5 0 ^ 0 . f o r 60 m in u te s , th e n w a sh e d w i t h d i s t i l l e d w a t e r by d é c a n t a t i o n . e x p e r im e n t,
In th e above
th e t e m p e r a t u r e o f t h e r e a c t i o n m ix tu r e a f t e r
c o m p le tio n o f t h e f i r s t r u n i s an y w h ere b e tw e e n 50 t o 7 5 * 0 . I t w as shown t h a t i f t h e m ix tu r e w as c o o le d r a p i d l y , t h e s u b s e q u e n t r u n u s i n g th e same o a t a l y s t sam p le i s n o t a s f a s t a s when t h e r e a c t i o n m i x t u r e i s a llo w e d to c o o l s lo w ly u n d e r a h y d ro g e n a tm o s p h e r e .
The w a s h in g o f t h e c a t a l y s t a f t e r
d i g e s t i o n w i t h d i s t i l l e d w a t e r may b e e q u i v a l e n t to a r a p i d c o o lin g .
T h a t i s why a slo w c o o l i n g t o room t e m p e r a t u r e by
f l u s h i n g w i t h h y d ro g e n a n d s t o p p e r i n g th e f l a s k h a s b e e n recom m ended i n t h e o a t a l y s t p r e p a r a t i o n a n d r e a c t i v a t i o n g iv e n above.
45 P i g , 18
E f f e c t o f R a p id C o o lin g o f C a t a l y s t i n Open A ir
H ydrogen Aba o rb e d p •a •i •
15.0
10.0
5 .0
0 0
5
10
15
Time — m in u te s
o B la n k Run + S e c o n d r u n o v e r th e same c a t a l y s t .
46
F i g . 19 E f f e c t o f G ra d u a l C o o lin g o f C a t a l y s t u n d e r H y d ro g en P r e s s u r e
15.0 H y d ro g en A b so rb e d p .s .i.
10.0
II.
5 .0
B la n k r u n S e c o n d ru n o v e r th e same c a t a l y s t
0
10 Time
minutes
47
A W~4 o a t a l y s t p r e p a r e d , by m o d ify in g th e p ro c é d u re g iv e n by P a v l l o an d A d k in s, by c a r r y i n g o u t t h i s slo w c o o lin g u n d e r h y d ro g e n a tm o sp h e re b e f o r e w ashing w ith d i s t i l l e d w a te r was shown to b e v e ry h ig h ly a c t i v e ( P ig . 13) •
I t i s c h a ra c te riz e d
by a h ig h i n i t i a l r a t e and r a p id r i s e t o th e maximum r a t e . However, w h e th e r t h i s i s due to th e a d d i t i o n a l s te p i s n o t c o n s id e r e d c o n c lu s iv e ly p ro v e d . I t i s n o t known w h e th e r th e lo w e re d a c t i v i t y when th e o a t a l y s t i s s u b je c te d to sudden c o o lin g a f t e r i t h ad b e e n u s e d i n th e e x o th e rm ic r e a c t i o n i s due to th e sudden te m p e r a tu re ch an g e o r w h e th e r th e c a t a l y s t i s more s e n s i t i v e to oxygen p o is o n in g (31) when i t i s h o t . Age.
The e f f e c t o f ag e on c a t a l y t i c a c t i v i t y was s tu d i e d by
P a t t i son (31) who o b s e rv e d a slow d e c li n e i n a c t i v i t y w ith a g e . The e f f e c t o f ag e i s m o st n o t i c e a b l e when u s in g in th e t e s t p r o c e d u re p ro p o se d i n P a r t I w here i t i s shown t h a t th e l i q u i d volume e f f e c t d is a p p e a r s a s th e c a t a l y t i c a c t i v i t y g o e s down (P ig * 9 ) .
Even th e n th e o a t a l y s t may be s t i l l c o n s id e r e d to
b e o f good a c t i v i t y . D e n s i ty .
A u d ib e r t an d R ain ea u (4) have c o n c lu d e d t h a t th e
d e n s it y o f an a c t i v e c a t a l y s t i s
alw a y s l e s s th a n t h a t o f
i n e r t m o d ific a tio n .
p ro b a b le t h a t d e n s ity a lo n e
W hile i t i s
an
h a s l i t t l e b e a r in g on a c t i v i t y ( 1 8 ), n e v e r t h e l e s s , i t i s p a r t i c u l a r l y i n t e r e s t i n g t o o b se rv e t h a t c a t a l y s t l i ( R ) 2 - 6 3 , w h ich was shown to be more a c t i v e th a n H i(R )2 -2 6 , gave an a v e ra g e w e ig h t when m easu red o u t w ith a g l a s s spoon much l e s s
48
th a n t h a t o f th e l a t t e r .
îPhe w e ig h ts w ere 0 .4 9 g . a g a i n s t
0 .5 9 g . , i n d i c a t i n g a lo w er d e n s ity f o r th e m ore a c t i v e c a t a l y s t ( s e e T a b le s 1 and 4 ) . Summary.
B e n e f i c i a l e f f e c t o f hydrogen g a s in m a in ta in in g th e
c a ta ly tic a c tiv ity
o f Raney n i c k e l c a t a l y s t was shown.
The
c a t a l y s t i s s u b je c te d to a d e c re a s e d a c t i v i t y i f c o o le d r a p i d ly in open a i r .
P r o c e d u re s w ere g iv e n f o r th e p r e p a r a t i o n o f a
Raney n i c k e l c a t a l y s t a n d f o r r e a c t i v a t i o n o f c a t a l y s t w hich h a d l o s t some o f i t s a c t i v i t y due to age o r to u s e in p u r if y i n g o r g a n ic l i q u i d s .
49
PART I I I THE BPPEOT OF IIQ U IP VOLUME AED THE AMOUET OF CATALYST OE THE RATE OF LIQUID PHASE ÏÏYDROOMTATIOE In tro d u c tio n I t was shown p r e v io u s ly t h a t th e r a t e o f h y d ro g en g a s a b s o r p tio n i n th e l i q u i d p h a se h y d ro g e n a tio n o f s ty r e n e o v e r f r e s h l y p r e p a r e d Raney n i c k e l c a t a l y s t i n a P a r r lo w - p r e s s u r e s h a k in g a p p a r a tu s v a r i e s w ith th e t o t a l l i q u i d volum e w h e th e r s ty r e n e i s u s e d a lo n e o r w ith a s o lv e n t .
I t was s u g g e s te d
t h a t t h i s d i f f e r e n c e c o u ld n o t b e w h o lly a t t r i b u t e d t o w hat i s c a lle d a " s o lv e n t” e f f e c t.
F u rth e rm o re , th e h y d ro g e n a tio n
v e l o c i t y i s n o t a lw a y s p r o p o r t i o n a l to th e am ount o f c a t a l y s t . Inasm uch a s th e h y d ro g e n a tio n r a t e g o es up a t f i r s t w ith l i q u i d volum e, o t h e r f a c t o r s b e in g e q u a l, i t seems r e a s o n a b le to su p p o se t h a t an optimum d i s p e r s io n o f th e c a t a l y s t p a r t i c l e an d , t h e r e f o r e , maximum c a t a l y t i c s u r f a c e e x p o s u re , i s n o t r e a l i z e d a t th e s m a lle r volum es and t h a t th e e f f e c t o f i n c r e a s i n g t h e amount o f l i q u i d i s to i n c r e a s e th e d i s p e r s io n o f th e c a t a l y s t .
S in c e th e s o l i d c a t a l y s t p a r t i c l e i s
s u rro u n d e d by l i q u i d a t a l l tim e s , th e d is p e r s io n o f th e c a t a l y s t s h o u ld n o t have much e f f e c t on th e s ty r e n e .
On th e
o t h e r h an d , th e p r o c e s s e s and r e a c t i o n ta k in g p la c e on th e s u r f a c e may be f a s t enough t h a t th e e x t e n t o f s u r f a c e a r e a ex p o sed to d i r e c t h y d ro g en bom bardment may c o n c e iv a b ly become r a t e d e te r m in in g .
T h is p i c t u r e r e q u i r e s th e c o n c e p t o f c a t a l y s t
p a r t i c l e s b lo c k in g e a c h o t h e r a g a i n s t d i r e c t h y d ro g en m o lecu le
50
bom bardm ent, t h i s e f f e c t b e in g re d u c e d a s the l i q u i d volum e i s i n c r e a s e d a n d th u s s e p a r a t i n g th e c a t a l y s t p a r t i c l e s . The above p i c t u r e o f c a t a l y s t a c tio n h a s b een u s e d s u c c e s s f u l l y to p r e d i c t th e h y d ro g e n a tio n v e l o c i t i e s o f s ty r e n e o v e r Raney n i c k e l w ith ch an g es in th e am ount o f c a t a l y s t and i n th e volum e o f t o t a l l i q u i d .
In a d d i t i o n , some s e p a r a t e and
d i f f e r e n t o b s e r v a tio n s i n h e te ro g e n e o u s c a t a l y s i s made by o th e r i n v e s t i g a t o r s seem e x p l a i n a b le and p o s s ib l e o f c o r r e l a t i o n on b a s i s o f t h i s m o d el. P r in c ip le s The f o llo w in g s t e p s a r e in v o lv e d in c a t a l y t i c h y d ro g e n a tio n ; th e d i f f u s i o n o f th e r e a c t a n t s (h y d ro g en and th e hydrogen a c c e p to r ) t o th e c a t a l y s t s u r f a c e , th e p r o c e s s o f a d s o r p ti o n , th e c h e m ic a l r e a c t i o n p r o p e r on th e c a t a l y s t s u r f a c e , th e p r o c e s s o f d e s o r p tio n o f th e p r o d u c t from th e a c t i v e c e n t e r in su c h a way t h a t p e r m its a c t i v a t i o n o f new m o le c u le s , and th e d i f f u s i o n o f th e r e a c t i o n p ro d u c t away from th e c a t a l y s t su rfa c e .
The g r e a t e r th e sp e e d o f th e v a r io u s p h a s e s , th e
s h o r t e r t h e tim e r e q u i r e d to go th ro u g h t h i s c a t a l y t i c c y c l e . What i s m eant by th e a c t i v i t y of th e c a t a l y s t dep en d s on th e fre q u e n c y o f t h i s c y c le ( 3 2 ) . S in c e th e h y d ro g en i s i n th e g a s p h a se and th e s ty r e n e in t h e l i q u i d p h a s e , f o r th e p u rp o se o f d is c u s s io n th e d i f f u s i o n o f th e h y d ro g en m o lecu le to th e c a t a l y s t s u r f a c e h a s b een s e p a r a t e d from th e a d s o r p tio n o f th e h y d ro g en an d th e - d if f u s io n and a d s o r p tio n o f th e s ty r e n e on th e c a t a l y s t
51
su rfa c e .
T hese l a s t t h r e e p h a s e s have b e e n lum ped t o g e t h e r
w ith t h e s u b s e q u e n t s t e p s l i s t e d above a n d th e whole th i n g r e f e r r e d to a s s u r f a c e p r o c e s s e s and r e a c t i o n . L e t u s c o n s id e r th e oatailsGt p a r t i c l e s a s s o l i d s p h e r e s o f u n ifo rm s i z e .
T h is i s o b v io u s ly an o v e r - s i m p l i f i c a t i o n b u t
t h i s r e p r e s e n t a t i o n s i m p l i f i e s c a l c u l a t i o n s and m akes i t e a s i e r to p i c t u r e t h e p r o c e s s o f c a t a l y s t a c t i o n . The f o llo w in g a s s u m p tio n s a r e made i n d e v e lo p in g a w o rk in g m odel o f th e h y d ro g e n a tio n o f s ty r e n e o v e r Raney n i c k e l c a t a l y s t : 1.
T h a t t h e r e a c t i o n ta k e s p la c e on th e c a t a l y s t s u r f a c e .
2.
T h a t th e s u r f a c e p r o c e s s e s an d r e a c t i o n a r e v e r y f a s t and any r e a c t i n g h y d ro g en m o le c u le c o l l i d i n g w ith th e c a ta ly s t su rfa c e re a c ts in s ta n tly .
However, e v e ry
h y d ro g e n m o le c u le c o l l i d i n g w ith th e c a t a l y s t s u r f a c e i s n o t g o in g to r e a c t .
I t w i l l r e a c t i f a hyd ro g en
m o le c u le , a s ty r e n e m o le c u le a t th e a c t i v e c e n t e r s c o n c e rn e d have gone th ro u g h a c y c le and th e c e n t e r s in v o lv e d a r e re a d y f o r th e n e x t r e a c t i o n . 3.
T h a t th e p e r i o d o f o s c i l l a t i o n o f th e c a t a l y s t p a r t i c l e i s slow r e l a t i v e to th e p e r io d f o r th e c a t a l y s t c y c l e . Due to th e c o n s ta n t s h a k in g o f th e r e a c t i o n f l a s k , a p o i n t on th e c a t a l y s t s u r f a c e may be c o n s id e r e d to move fro m one d i r e c t i o n to th e o t h e r by r o t a t i o n o f th e c a t a l y s t p a r t i c l e a t some a v e ra g e fre q u e n c y ( F ig . 2Cb).
4.
T h a t when two o r more p a r t i c l e s a r e c lo s e t o g e t h e r , e a c h c a n n o t f u l l y ex p o se i t s t o t a l s u r f a c e a r e a to th e
52
d i r e c t h y d ro g en m o le c u le bom bardm ent b e c a u s e p a r t o f i t i s b lo c k e d by th e o t h e r s .
T h is e f f e c t a f f e c t s
th e t o t a l num ber o f m o le c u le s r e a c t i n g p e r u n i t tim e and e x i s t s o n ly u n d e r c o n d it io n s g iv e n ab o v e ; t h a t th e s u r f a c e r e a c t i o n and p r o c e s s e s a r e v e r y f a s t and t h a t th e p e r io d o f o s c i l l a t i o n o f t h e c a t a l y s t p a r t i c l e s i s slow r e l a t i v e to t h i s . 5.
T h a t th e m e asu red r a t e o f h y d r o g e n a tio n i s p r o p o r t i o n a l to th e e f f e c t i v e s u r f a c e a r e a a s d e te rm in e d by c o n d i t i o n s g iv e n above an d n o t to th e t o t a l s u r f a c e are a .
6.
T h a t t h e r e i s a c e r t a i n optimum r a t i o o f c a t a l y s t w e ig h t to l i q u i d volum e, i . e . , one p a r t i c l e o f c a t a l y s t p e r u n i t volum e, a t w h ich th e h y d r o g e n a tio n r a t e i s maximum.
A t t h i s r a t i o , th e e f f e c t i v e s u r f a c e
a r e a an d th e t o t a l s u r f a c e a r e a o f th e c a t a l y s t c o in c id e .
T h is means t h a t when th e am ount o f
c a t a l y s t i s d o u b le d , th e volum e a t w h ich th e maximum r a t e o c c u rs i s a l s o d o u b le d . The e f f e c t i v e s u r f a c e a r e a e x i s t s o n ly u n d e r c o n d it io n s o f t h e e x p e r im e n t.
I t i s p ro b a b ly b e s t e x p r e s s e d in te rm s o f
c o o r d i n a t e s s in c e by t h i s tr e a t m e n t, i t i s p o s s ib le to t a l k a b o u t s u r f a c e w ith o u t any s p e c i f i c s ta te m e n t a b o u t th e a c t u a l su rfa c e a re a .
L e t th e c e n t e r o f th e c a t a l y s t s p h e re be th e
o r i g i n o f th e t h r e e c o o r d i n a t e s , x , y , and z , and th e s i x p ro je c tio n s ,
jhy and + z, r e p r e s e n t th e t o t a l s u r f a c e a r e a .
A t th e optimum volum e f o r a g iv e n am ount o f c a t a l y s t , th e
53
F ig* 20
R e l a t i v e S u r fa c e E xp o su re Based on S p h e r ic a l P a rtic le s +Z —\ f-
'
♦X a . P e r io d o f P a r t i c l e O s c illa tio n
e
S ix p r o j e c t i o n s to d e s ig n a te f u l l o u te r s u r f a c e a r e a ex p o su re .
b . One p a r t i c l e p e r u n i t volume t o g iv e f u l l s u r f a c e e x p o su re a n d , t h e r e f o r e , maximum r a t e Two p a r t i c l e s p e r u n i t volum e. d , e . T hree p a r t i c l e s p e r u n i t volum e.
54
e f f e c t i v e s u r f a c e a r e a e q u a ls th e t o t a l s u r f a c e a r e a an d i s a l s o r e p r e s e n t e d hy a l l s i x p r o j e c t i o n s o f e x p o s u re (F ig * 20 h ) . The e x t e n t o f th e e f f e c t i v e s u r f a c e a r e a r e l a t i v e to th e t o t a l s u r f a c e a r e a d ep en ds on two f a c t o r s :
(1 ) th e p e r io d o f
th e c a t a l y t i c c y c le and (2 ) t h e p e r io d o f t h e p a r t i c l e o s c illa tio n .
The h y d ro g e n a tio n o f s t y r e n e seem s to c o r re s p o n d
to th e l i m i t i n g c a s e w here th e p e r io d o f th e c a t a l y t i c c y c le i s v e ry much f a s t e r th a n t h e p e r io d o f th e p a r t i c l e o s c i l l a t i o n . S t a r t i n g w ith a volum e o f s ty r e n e o r s ty r e n e i n a s o lv e n t an d an am ount o f c a t a l y s t i n th e optimum r a t i o f o r maximum h y d ro g e n a tio n r a t e , d o u b lin g th e am ount o f c a t a l y s t d o u b le s th e c a ta ly tic su rfa c e a re a .
However, i f th e volum e i s k e p t
c o n s ta n t an d t h e p a r t i c l e s a r e c lo s e t o g e t h e r , th e e f f e c t i v e s u r f a c e a r e a i s n o t d o u b le d .
E ach p a r t i c l e c o n t r i b u t e s o n ly
5 /6 o f i t s s u r f a c e a r e a s i n c e 1 /6 o f i t i s b lo c k e d by th e o th e r.
The e f f e c t i v e s u r f a c e a r e a , t h e r e f o r e , i n c r e a s e s o n ly
2 X 5 /6 o r 5 / 3 tim e s t h a t o f th e o r i g i n a l am ount ( s e e F i g . 20 0 ) . By t r i p l i n g th e am ount o f c a t a l y s t , th e e f f e c t i v e a r e a g o es up 7 / 3 tim e s i n s t e a d o f t h r e e tim e s , s in c e o f th e t h r e e p a r t i c l e s i n th e u n i t vo lum e, one i s b lo c k e d on two s i d e s , w h ile each o f th e o t h e r two a r e b lo c k e d on one s i d e . As th e number o f p a r t i c l e s i n c r e a s e s p e r u n i t volume o f l i q u i d i n c r e a s e s t h e p o s s i b l e c o m b in a tio n o f c a t a l y s t p o s i t i o n s in c re a s e s .
The a v e ra g e i n c r e a s e i n e f f e c t i v e s u r f a c e a r e a w i l l
b e fo u n d to b e c l o s e to th e f i g u r e c a l c u l a t e d by c o n s id e r in g th e c a t a l y s t p a r t i c l e s a r r a n g e d i n a s t r a i g h t l i n e .
The
55
f o llo w in g t a b l e g iv e s th e i n c r e a s e in e f f e c t i v e a r e a w it h th e num ber o f p a r t i c l e s p e r u n i t v o lu m e. T ab le 5 num ber o f P a r t i c l e s p e r U n it Volume and th e E f f e c t i v e S u r fa c e A rea num ber o f p a r t i c l e s 1
2 3 4 6 6 7 8 9 10
In c re a s e in E ffe c tiv e s u r f a c e a r e a ______ 1
5 /3 7 /3 3 1 1 /3 1 3 /3 6 1 7 /3 1 9 /3 7
I f i n s t e a d o f i n c r e a s i n g th e am ount o f c a t a l y s t ,
th e
volum e o f th e l i q u i d i s d e c r e a s e d , s t a r t i n g from th e volum e w h ich i s a t th e optimum f o r th e am ount o f c a t a l y s t p r e s e n t , th e e f f e c t i v e s u r f a c e a r e a s h o u ld d e c r e a s e a c c o r d in g to th e r e c i p r o c a l s o f th e im p ro p e r f r a c t i o n s g iv e n above i f th e am ount o f c a t a l y s t i s k e p t c o n s ta n t a s th e volume i s c u t down to 1 / 2 , 1 / 3 , 1 / 4 , e t c .
56
Table 6 E f f e c t i v e S u r fa c e A rea f o r C o n s ta n t Amount o f C a t a l y s t w i t h D e c re a s e i n l i q u i d Volume Volume d e c r e a s e
D e c re a s e i n e f f e c t i v e su rfa c e a re a
I
É
a /ll 3 /lS 1 /5 3 /1 7 3 /1 9 1 /7
1 /5 1 /6 1 /7 1 /8 1 /9 1 /1 0
From th e t r e n d o f th e f i g u r e s f o r th e e f f e c t i v e s u r f a c e a r e a s f o r th e c o r re s p o n d in g f r a c t i o n s to w hich th e volum e i s r e d u c e d , i t may he s e e n t h a t th e e f f e c t i v e s u r f a c e a r e a , f , can he e x p r e s s e d by t h e e m p ir ic a l e q u a tio n f
=
3 "1--------4— 57nr
w here ”n ” i s th e f r a c t i o n to w hich th e o r i g i n a l optimum volum e i s red u ced . S in c e th e m ea su re d h y d ro g e n a tio n r a t e s a r e assum ed to be p r o p o r t i o n a l to th e e f f e c t i v e s u r f a c e a r e a , a c u rv e show ing th e ch an g e i n r a t e w ith l i q u i d volume may be p l o t t e d from th e v a lu e s g iv e n a b o v e . and volum e Vw h ic h used,
3 / 6 Ei s
L e t t i n g E s ta n d f o r th e h y d ro g e n a tio n r a t e i s th e optimum f o r th e
th e r a t e a t l/S V ,
am ount o f c a t a l y s t
3 /7 E , a t l/4 V , e t c .
(se e
F i g . 2 1 )• To se e w h e th e r a p a r t i c u l a r s e t o f e x p e r im e n ta l d a ta c h e c k s w ith su ch a c u r v e , i t i s f i r s t n e c e s s a r y to d e te rm in e
57
F ig . 21
T h e o r e t i c a l C urves Showing Change o f R ate w ith 5 0 ^ D ecrease o r lOO'^ I n c r e a s e i n th e Amount o f C a t a l y s t
3R R ate
1 0 /9 2R
-
2 /3 R 5 /3 —
— j!---------
2V L iq u id Volume
58
fro m a p o r t i o n o f th e e x p e r im e n ta l d a ta th e volume w h ich s h o u ld g iv e th e maximum r a t e f o r th e am ount o f c a t a l y s t u s e d an d th e v a lu e o f t h i s maximum r a t e i t s e l f .
Knowing th e s e th e c o m p le te
c u rv e can be p l o t t e d a s i l l u s t r a t e d i n th e p a r a g ra p h above an d th e re m a in d e r o f th e e x p e r im e n ta l d a ta c h e c k e d to see w h e th e r th e y f a l l on t h i s c u r v e . A c c o rd in g to a s s u m p tio n 6, i f V i s th e optimum volum e f o r a c e r t a i n am ount, say one u n i t , o f c a t a l y s t an d th e R, th e c o r re s p o n d in g r a t e ,
th e n f o r tw ic e th e am ount, i . e . ,
2 u n its ,
o f c a t a l y s t th e optimum volume i s 27 an d t h e r a t e i s
(2 5 /9 )R .
T h is l a t t e r f i g u r e i s a r r i v e d a t a s f o llo w s :
A t 7 f o r one u n i t
o f c a t a l y s t th e r a t e i s R.
F o r two u n i t s o f c a t a l y s t a t 7 ,
th e r a t e g o es up to 5 / s R.
T h is , i n t u r n , i s o n ly 3 /5 o f th e
r a t e a t 2 7 , w h ich a c c o r d in g ly , s h o u ld b e 6 /3 x ( 5 / S ) R o r ( 2 5 /9 ) B .
T h is r e l a t i o n i s diagram m ed i n F i g . 2 1 .
When d a ta
o f th e h y d ro g e n a tio n r a t e s o f d i f f e r e n t volum es o f s ty r e n e f o r a c e r t a i n am ount o f c a t a l y s t a r e a v a i l a b l e , th e r a t e s a t th e same l i q u i d volum es f o r m u l t i p l e s o r f r a c t i o n s o f t h i s am ount o f c a t a l y s t s h o u ld b e p r e d i c t a b l e .
T h is h a s been fo u n d to be
so. Two m ethods o f c a l c u l a t i n g th e optimum c a t a l y s t - l i q u i d volum e r a t i o w i l l b e i l l u s t r a t e d i n c o n n e c tio n w ith th e s o l u t i o n o f p ro b le m s .
59
E x p e rim e n ta l The a p p a r a tu s an d p ro c e d u re i n r u n n in g th e h y d r o g e n a tio n s w ere d e s c r i b e d i n P a r t I o f t h i s t h e s i s . R e s u l t s and D is c u s s io n The m e a su re d h y d r o g e n a tio n v e l o c i t i e s f o r th e a s c e n d in g p o r t i o n o f th e r a t e - l i q u i d volum e c u rv e o v e r one l e v e l s p o o n fu l ( c a . 0 .9 g . m o is t w e ig h t i n d io x a n ) o f c a t a l y s t d e s ig n a te d M ( R ) l - 7 3 , p r e p a r e d by th e m ethod g iv e n by P a v li c an d A d k in s ( 3 3 ) , a r e a s f o llo w s : Run
S ty re n e
90-B 91-B 92-A
25 m l. 50 75
I n i t i a l tem p. 2 7 .0 ^ 0 . 2 8 .4 2 6 .6
R a te 0 .7 6 p s i/m i n . 1 .1 5 1 .5 0
To c a l c u l a t e th e optimum volum e o f s ty r e n e w hich t h e o r e t i c a l l y w ould g iv e th e maximum r a t e o f h y d ro g e n a tio n f o r th e am ount o f c a t a l y s t u s e d , a g ra p h i s drawn and th e l i n e p r o je c t e d beyond th e a s c e n d in g p o r ti o n o f th e c u rv e ( s e e F i g . 22) The p a r t i c u l a r volum e on th e c u rv e whose r a t e i s 5 /3 tim e s t h a t o f a volum e one h a l f i n m a g n itu d e i s th e volum e c o r re s p o n d in g t o th e optimum r a t i o .
The v a lu e o f 1 .8 0 p . s . i . / m i n . a t 100 m l.
and 1 .1 0 p . s . i . / m i n . a t 50 m l. a p p ro x im a te ly b e a r t h i s re la tio n .
The optimum volum e i s ,
t h e r e f o r e , 100 m l.
For
tw ic e th e am ount o f c a t a l y s t th e optimum volume i s 200 m l. and th e c o r r e s p o n d in g r a t e , 2 5 /9 x 1 .8 0 p . s . i . / m i n . o r 5 .0 0 P * S .l ./ m i n .
The c a l c u l a t e d v a lu e s f o r th e h y d ro g e n a tio n o f
s ty r e n e o v e r a p p ro x im a te ly 2 x 0 .9 m o is t w e ig h t o f B l( R ) l- 7 3 a r e g iv e n in T able 7 .
60
F ig . 23P
G raphioal D eterm in a tio n o f th e Optimum Volume
1.60 P r o je o te d curve
rate
A ctu a l Curve
1.00
0 .7 0 25
50
75
100
Volume o f S tyren e — m l.
125
61
T a b le 7 P r e d i c t e d H y d ro g e n a tio n R a te s o f D i f f e r e n t Amounts o f S ty re n e O ver 2 x 0 .9 g . M o is t W eight o f H i(R )1 -7 3 Volume d ec re a se
C a lc u la te d r a t e s
A c tu a l volum e
I
5 .0 0 3 .0 0 2 .1 5 1 .6 5 1 .3 5 1 .1 5 1 .0 0 0 .9 0
200 m l. 100 67 50 40 33 2 8 .5 25
p .s .i./m in . ( 3 /5 X 5 .0 0 ) ( 3 /7 X 5 .0 0 ) ( 1 /3 X 5 .0 0 ) (3 /1 1 X 5 .0 0 ) (3 /1 3 X 5 .0 0 ) ( 1 /5 X 5 .0 0 ) (3 /1 9 X 5 .0 0 )
T ab le 8 H y d ro g e n a tio n R a te o f D i f f e r e n t Amounts o f S ty re n e Over Two l e v e l S p o o n sfu l ( c a . 2 x 0 .9 g . M o is t W eight i n D ioxan) o f H l( R ) l- 7 3 Run Ho.
Volume o f s ty r e n e
95-A 2-5A 94-0 95-B 94-A
75 m l. 60 50 35 26
I n i t i a l m ix tu re te m p e r a tu re 2 6 .1 ^ 0 . 2 7 .4 2 7 .8 2 9 .5 2 6 .8
H y d ro g e n a tio n ra te 2 .2 5 p s i/ m in . 1 .9 0 1 .4 5 1 .2 0 0 .9 0
T h a t th e c a l c u l a t e d c u rv e i s i n f a i r l y good a g re e m e n t w ith th e e x p e r im e n ta lly o b ta in e d c u rv e c an be se e n i n th e g ra p h p lo tte d in F ig . 23.
62
Pig* 23 C a lc u la te d and E xperim ental Hydrogena. t i e n B a tes o f S tyren e
2 .5 0
2.00
1 .5 0
1.00 O E xperim ental Bate 4 - O a lc u la te d Rate 0 .5 0
50 Volume o f S tyren e
75 m l.
62
The seco n d p ro b le m i s s i m i l a r to th e f i r s t e x c e p t t h i s
tim e th e l i q u i d i s a s o l u t i o n o f s ty r e n e i n e th a n o l m ixed in 1 :2 p a r t s by vo lu m e.
Ih e c a l c u l a t i o n i s i n th e r e v e r s e d i
r e c t i o n i n t h a t th e r a t e s f o r h a l f th e am ount o f c a t a l y s t i s to be c a l c u l a t e d .
As i n th e f i r s t c a s e , th e volum e w h ich
g iv e s th e maximum r a t e f o r th e am ount o f c a t a l y s t u s e d i s d e te rm in e d f i r s t .
I n th e p r e c e d in g exam ple th e c a l c u l a t i o n
o f t h i s volume c o u ld b e done g r a p h i c a l l y b e c a u s e i t d id n o t l i e much beyond th e e x p e r im e n ta l v a l u e s .
I n o a s e s w here th e
optimum volum e i s f a r beyond th e e x p e r im e n ta l r e g io n , a n o th e r m ethod m ust b e u s e d . When th e optimum volume l i e s f a r beyond th e e x p e rim e n ta l r e g i o n , t h i s v a lu e c a n n o t be d e te rm in e d w ith p r e c i s i o n .
T h is
i s r e a d i l y u n d e rs to o d when i t i s c o n s id e r e d t h a t th e volum e i t s e l f may be 10 to 20 tim e s th e d i f f e r e n c e s i n th e volum es u s e d i n th e e x p e r im e n ts .
F u rth e rm o re , th e r a t e change w ith
volum e becomes s m a l l e r a s th e optimum volume i s a p p ro a c h e d and may l i e w ith in e x p e r im e n ta l e r r o r o v e r a w ide r a n g e .
The
r e g io n o f th e optimum v a lu e may n e v e r t h e l e s s be w e l l a p p r o x i m ated fro m e x p e r im e n ta l r a t e s a t th r e e o r f o u r d i f f e r e n t v o lu m e s. T h is s e c o n d i s a m ethod by a p p ro x im a tio n .
The v a lu e o f
th e p r o d u c t o f th e optimum volum e and th e maximum r a t e a t t h i s volum e i s s o lv e d by u s in g th e d a ta on two ( p r e f e r a b l y more) o f th e m easu red r a t e s and th e c o r re s p o n d in g v o lu m es.
64
Table 9 H y d ro g e n a tio n R a te s o f D i f f e r e n t Volumes o f a M ix tu re o f 8 t y r e n e - E th a n o l in 1 :2 P a r t s by Volume Volume o f s t y r e n e C a ta ly s t* e t h a n o l m ix tu re ___________________ 85 m l. 75 60
R a te ____
1 .1 6 g . 1 .1 5 1 .1 2
* O a t a l y s t d e s ig n a te d R i(R )2 -2 6 .
2 .9 0 2 .5 0 2 .0 5
p s i./m in .
A ge, one m onth.
I n T ab le 9 a r e l i s t e d th e e x p e r im e n ta l h y d r o g e n a tio n r a t e s o f a s o l u t i o n o f s t y r e n e in e th a n o l o v e r a p p ro x im a te ly 1 .1 5 g . o f c a ta ly s t.
I f 85 m l. w ere l / 2 o f th e optimum volum e, th e
r a t e a t t h i s volum e w i l l be 2 .9 0 p . s . i . / m i n . x 6 /3 o r 4 .8 4 p . s . i . / m i n .
(U se T ab le 6 ) .
The p r o d u c t o f th e optimum
volume an d th e r a t e i s th e n , 170 m l. x 4 .8 4 p . s . i . / m i n .
If
86 m l. w ere l / 3 o f th e optimum volum e, th e maximum r a t e f o r t h i s volume w i l l be 2 .9 0 p . s . i . / m i n . x 7 /3 o r 6 .7 6 p . s . i . / m i n . By a ssu m in g 85 m l. to b e l / 4 , l / 5 , l / 6 ,
e t c . , o f th e optimum
volum e, o t h e r p r o d u c ts o f th e assum ed optimum volume and th e c o r r e s p o n d in g maximum r a t e a r e o b ta in e d .
T h is p ro c e d u re i s
r e p e a t e d f o r 2 .5 0 p . s . i . / m i n . and 75 m l. and ( o r) 2 .0 6 p . s . i . / m i n . a t 60 m l. th e same c u r v e ,
S in c e th e s e e x p e r im e n ta l p o i n t s l i e
on
somewhere a lo n g th e way, th e p r o d u c t o f the.
assum ed optimum volum e and th e c o r re s p o n d in g r a t e s h o u ld be a b o u t e q u a l.
These w i l l be th e d e s ir e d v a lu e s o f th e optimum
volum e an d r a t e .
The c a l c u l a t i o n s f o r th e s o l u t i o n o f th e
optimum f o r th e above s e t o f d a t a i s g iv e n b e lo w .
66
75 m l. 2 .5 0 p s i . / m i n .
F ra c tio n o f assum ed o p t i mum volum e
I
85 m l. 2 .9 0 p s i . / m i n ,
625* 1315 2250 3440 5850 6570 8500 10700
822 1720 2960 4530 6410 8610 11200
* U n it, m l. p . s . i . / m i n . Only n u m e ric a l v a lu e s a r e o f any s i g n i f i c a n c e , h ow ever. The f r a c t i o n 1 /7 f o r 75 m l. and l / 6 f o r 85 m l. and 1 /8 f o r 75 m l. and l / 7 f o r 85 m l. g iv e th e c l o s e s t p a i r s o f a n s w e rs . F o r th e f i r s t p a i r th e optimum v a lu e i s 525 m l. to 510 m l. and f o r th e se c o n d p a i r , 600 m l. to 595 m l.
As a f i r s t
a p p ro x im a tio n , i t i s th u s e s t a b l i s h e d t h a t th e optimum volum e i s i n th e r e g io n o f 500 m l. to
600 m l.
A c l o s e r a p p ro x im a tio n i s
550 m l.
The p r o d u c t
o f volum e
and r a t e a t d i f f e r e n t assum ed optimum volum es a r e a s f o llo w s ; Assumed optimum volume 500 550 500
60 m l. 2 .0 5 p s i . / m i n . 6050 7290 8610
75 m l. 2 .5 0 p s i . / m i n . 5970 7200 8500
85 m l. 2 .9 0 p s i . / m i n . 6160 7400 8750
The maximum r a t e , by w h ich th e assum ed optimum volume i s m u l t i p l i e d , i s c a l c u l a t e d by u s in g th e e m p ir ic a l e q u a tio n f =
3 . w h ich w as g iv e n b e f o r e . The r e c i p r o c a l o f t h i s 1 ♦ 2/n e q u a tio n i s th e f a c t o r by w hich th e e x p e r im e n ta l r a t e i s m u l t i p l i e d to g e t th e maximum r a t e a t any p a r t i c u l a r v olum e.
66
The p r o d u c ts f o r 550 m l. have th e s m a l l e s t p e r c e n ta g e d i f fe re n c e s.
W hile th e optimum volume c a n n o t he d e te r m in e d w ith
p r e c i s i o n by th e d e s c r ib e d m ethod, th e an sw er o b ta in e d i s s u ita b le f o r p r a c t i c a l p u rp o se. T a k in g 550 m l. a s th e optimum v olum e, th e a v e ra g e maximum r a t e f o r t h i s volum e, d e te rm in e d from th e t h r e e e x p e r im e n ta l r a t e s , i s 13»3 p s i . / m i n .
F o r o n e - h a lf th e am ount o f c a t a l y s t ,
i . e . , 1 / 2 X 1 .1 5 g . , th e optimum volume and maximum r a t e a r e 275 m l. and 4 .8 0 (9 /2 5 x 1 3 ,3 ) p s i . / m i n .
I n T ab le 10 a r e
sum m arized th e e x p e r im e n ta l and o a l c u l a t e d h y d ro g e n a tio n v e l o c i t i e s u s in g o n e - h a l f th e am ount o f c a t a l y s t . T a b le 10
( s e e F ig . 24)
O a lc u la te d and E x p e rim e n ta l H y d ro g e n a tio n R a te s o v e r c a . l / 2 x 1 .1 5 g . o f Raney l i o k e l C a t a l y s t Volume s ty r e n e e th a n o l m ix tu r e
C a ta ly s t
75 m l. 75 60 50
0 .6 0 g . 0 .5 9 0 .5 4 0 .5 9
E x p e rim e n ta l ra te
1 .7 5 p s i . / m i n . 1 .7 5 1 .5 0 1 .2 0
C a lc u la te d ra te
1 .7 3 p s i . / m i n . 1 .7 3 1 .4 3 1 .2 0
T hus, th e ch an g e in h y d ro g e n a tio n v e l o c i t i e s to w ard th e d i r e c t i o n o f m ore c a t a l y s t f o r s ty r e n e w ith o u t s o lv e n t , and to w ard t h a t o f l e s s c a t a l y s t f o r s ty r e n e w ith s o l v e n t , have b e e n w e ll a p p ro x im a te d f o r th e a s c e n d in g p o r ti o n o f th e r a t e l i q u i d volum e c u r v e .
However, th e e x p e r im e n ta l c u r v e s do n o t
go up to th e c a l c u l a t e d maximum n o r i s th e r e l a t i v e m a g n itu d e s
67
F i g .24 C a lc u la te d an d E x p e rim e n ta l H y d ro g e n a tio n R a te s f o r 50^ D e crease i n th e Amount o f C a ta ly s t
3 .0 0 R a te p .s .i. m in. 2 .5 0
2.00
1.50
1.00 50
75 L iq u id volume — m l.
S ty re n e i n e th a n o l ( 1 :2 p a r t s by volum e) y C a lc u la te d R ate O E x p e rim e n ta l R ate
68
o f th e o a t a l y s t and th e c a l c u l a t e d optimum volume su c h t h a t th e b lo c k in g e f f e c t w h ich h a s b e e n p o s t u l a t e d c a n e x i s t .
The
p a r t i c l e s m u st be c l o s e t o g e t h e r f o r such an e f f e c t to ta k e p la c e . I n a p a p e r on th e dep en d en ce o f th e r a t e o f h e te r o g e n e o u s c a t a l y t i c r e a c t i o n s on th e am ount o f c a t a l y s t , G o l 'd a n s k l l (15) h a s s u g g e s te d a r e l a t i o n s h i p b etw een th e I n t e r f a c l a l a r e a b etw een th e g a s and l i q u i d p h ase and th e c a t a l y t i c r a t e when th e t o t a l c a t a l y t i c s u r f a c e a r e a i s c o n s t a n t .
I t I s p o s s ib le
t h a t th e i n t e r f a c e b etw een th e g a s and l i q u i d p h a s e s I s th e r e a l f a c t o r I n s t e a d o f th e l i q u i d v o lu m e.
The I n t e r f a c l a l a r e a I s
a f u n c t io n o f th e t o t a l l i q u i d volum e, th e s i z e and shape o f th e r e a c t i o n f l a s k , and th e s h a k in g f r e q u e n c y .
The l a s t two
com ponents a r e k e p t c o n s ta n t so t h a t th e I n t e r f a c l a l a r e a I s d e te rm in e d more o r l e s s by th e l i q u i d v o lu m e.
The I n c r e a s e
In I n t e r f a c l a l a r e a w ith l i q u i d volume d o es n o t f o llo w a l l th e way b e c a u s e o f t h e l i m i t a t i o n p la c e d by th e s i z e an d o f th e re a c tio n f la s k .
F u r t h e r c o m p lic a tio n r e s u l t s b e c a u s e a s th e
l i q u i d volume I s I n c r e a s e d more an d more c a t a l y s t w i l l be found In th e l i q u i d body I n s t e a d o f n e a r o r a t th e i n t e r f a c e . I n T able 5 , th e I n c r e a s e In e f f e c t i v e c a t a l y t i c s u r f a c e a r e a w as fo u n d by t a k i n g a u n i t volume and a d d in g one, tw o, t h r e e , e t c . , p a r t i c l e s to t h i s .
I t was i n d i c a t e d t h a t th e
h y d ro g en m o le c u le s c o u ld a p p ro a c h th e c a t a l y s t p a r t i c l e s from a l l d i r e c t i o n s o f t h i s u n i t volum e.
S ty re n e can be k e p t u n d e r
h y d ro g en In th e p r e s e n c e o f Raney n i c k e l f o r a c o n s id e r a b le
69
p e r i o d o f tim e w ith o u t a p p r e c ia b le d ro p i n th e h y d ro g en p r e s s u r e i f t h e r e I s no s h a k in g and th e c a t a l y s t re m a in s s e t t l e d a t th e b o tto m o f th e f l a s k .
T h is shows t h a t th e
c a t a l y s t p a r t i c l e m u st b e n e a r o r a t th e i n t e r f a c e o f th e g a s and l i q u i d p h a s e s f o r th e h y d ro g e n a tio n to b e r a p i d .
T h e re fo re ,
a volume s m a ll enough to p e r m it hyd ro g en m o le c u le s to a p p ro a c h from a l l s i d e s , a s was assum ed f o r o u r m odel, may b e c o n s id e r e d to b e a l l s u r f a c e and w hat was r e f e r r e d to a s a p a r t i c l e p e r u n i t volum e may b e a l s o c o n s id e r e d a s a p a r t i c l e p e r u n i t In te rf a c la l a re a .
U n f o r t u n a t e ly , th e I n t e r f a c l a l a r e a i s n o t
e a s i l y d e te rm in e d so t h a t th e I n t e r f a c e h a s t o be s t i l l e x p r e s s e d I n a d e q u a te ly in te rm s o f th e l i q u i d v o lu m e. I n th e e x p e r im e n ta l w ork I t was found t h a t th e d e c r e a s e In h y d ro g e n a tio n v e l o c i t i e s s t a r t e d I n th e r e g io n o f 75 to 90 m l. o f l i q u i d .
A maximum r a t e w as assum ed f o r a c e r t a i n
optimum r a t i o o f c a t a l y s t w e ig h t to l i q u i d volum e.
W ith t h e
am ount o f c a t a l y s t em ployed th e optimum volume w as c a l c u l a t e d to b e beyond th e 75 to 90 m l. r e g i o n , an d , t h e r e f o r e , c o u ld n o t be shown t o e x i s t .
The am ount o f c a t a l y s t c an be re d u c e d
so t h a t th e optimum l i e s below t h i s r e g i o n .
In t h i s case I t
sh o u ld be fo u n d t h a t w h e re a s f o r th e u s u a l am ount o f c a t a l y s t u s e d ( c a . 0 .5 g .) t h e r e i s an I n c r e a s e I n r a t e w ith volum e, f o r th e s m a l l e r am ount o f c a t a l y s t t h e r e I s no I n c r e a s e I n th e same r e g i o n . from F i g . 2 5 .
T h is w as shown to be th e c a s e a s can be seen D a ta was p r e s e n te d In T ab le 1 .
T h is I s n o t
c o n c lu s iv e p r o o f b u t I t I n d i c a t e s t h a t th e optimum r a t i o o f c a t a l y s t to l i q u i d volum e f o r maximum r a t e i s n o t p u r e ly a
70
F i g . 25 D is p la c e m e n t o f Optimum Volume w ith th e R e d u c tio n i n th e Amount o f C a t a l y s t
2.00
R a te m ln. 1 .5 0
1.00
0 50
75 L iq u id Volume — m l. L iq u id m ix tu re c o n ta in in g s ty r e n e a n d e th a n o l i n r a t i o o f 1%2 p a r t s by v o lu m e. Lower c u rv e O b ta in e d w ith a b o u t o m e ~ fifth th e am ount o f c a t a l y s t u sed f o r th e u p p e r c u r v e .
71
m a th e m a tic a l f l o t io n . The h e a r i n g o f th e r e l a t i v e p e r i o d s o f p a r t i c l e s o s c i l l a t i o n and th e c a t a l y t i c c y c le on th e e f f e c t i v e s u r f a c e a r e a may h e shown i n te rm s o f th e i l l u s t r a t i o n s i n F i g . 2 6 . L e t th e l e n g t h o f th e s e m i - c i r c u l a r l i n e r e p r e s e n t th e tim e r e q u i r e d f o r a p o i n t on th e c a t a l y s t s u r f a c e a t A to move fro m t h e r e to a p o i n t A* hy th e r o t a t i n g o f th e c a t a l y s t p a r t i c l e due to s h a k in g .
E s s e n t i a l l y th e same e f f e c t may h e o h ta in e d
hy a p a r t i c l e hy a t r a n s l a to r y m o tio n from a p o s i t i o n a d j a c e n t to one to a p o s i t i o n a d j a c e n t to a n o t h e r .
L e t th e th i c k n e s s
o f th e l i n e B r e p r e s e n t th e tim e r e q u i r e d to c o m p lete th e re a c tio n , i . e . ,
th e p e r io d o f th e c a t a l y t i c c y c l e .
U nder s u c h
c ir c u m s ta n c e s , p o i n t A on th e c a t a l y s t s u r f a c e w i l l move on a n e g l l g l h l e d i s t a n c e d u r in g th e tim e a c a t a l y t i c c y c le i s c o m p le te d and th e e f f e c t i v e c a t a l y t i c s u r f a c e a r e a i s a p p ro x im a te ly t h a t c a l c u l a t e d on h a s l s o f a s t a t i c m o d e l, i . e . , th e f i g u r e s g iv e n i n T ah le 6 , However, i f th e p e r io d o f th e c a t a l y t i c c y c le i s l o n g e r , and i s e q u i v a l e n t to th e l e n g t h o f th e v e r t i c a l l i n e C, th e n p o i n t A w i l l move a n a p p r e c i a b l e d is ta n c e i n th e tim e i t t a k e s t o c o m p lete a c a t a l y t i c c y c l e .
A c tiv e c e n t e r s w h ich w ere
b lo c k e d from th e d i r e c t bom bardm ent o f h y d ro g en m o le c u le s a r e now e x p o se d w ith th e r e s u l t t h a t t h e r e i s a n i n c r e a s e i n e f f e c t i v e s u r f a c e a r e a r e l a t i v e to th e t o t a l s u r f a c e a r e a . F i n a l l y , when th e c a t a l y t i c c y c le i s slow a s c a u s e d hy n o t to o a c t i v e a c a t a l y s t , o r h y an i n h e r e n t l y slow r e a c t i o n , th e r e s u l t i s t h a t th e w hole c a t a l y s t s u r f a c e i s e x p o se d d u r in g
72
P ig . 26 R e la t iv e P e r io d s o f P a r t i c l e O s c i l l a t i o n and C a t a l y t i c C y c le
O0.. B
a
a
o© P e r io d o f P a r t i c l e O s c illa tio n
■X—
c
I P e r io d o f C a t a l y t i c C y c le
75
t h e p e r i o d i t t a k e s t o c o m p le te th e c a t a l y t i c c y c le and th e e f f e c t i v e s u r f a c e a r e a i s e q u a l to th e t o t a l s u r f a c e a r e a . The e f f e c t o f l i q u i d volume d is a p p e a r s b e c a u s e t h e r e i s no b lo c k in g e f f e c t ta k in g p l a c e . The above seem s to b e a r e a s o n a b le a n d p l a u s i b l e e x p la n a t i o n f o r th e d is a p p e a r a n c e o f th e l i q u i d volume e f f e c t a s th e c a t a l y s t a g e s and d e c l i n e s i n a c t i v i t y * The in f l u e n c e o f th e d e g re e o f a g i t a t i o n on th e h y d ro g e n a tio n r a t e o b s e rv e d i n p r a c t i c e h a s b e e n s tu d i e d by a few i n v e s t i g a t o r s ( 1 2 ,1 6 ,2 5 ) .
I n c r e a s i n g th e s h a k in g fre q u e n c y
i n c r e a s e s th e r a t e o f h y d ro g e n g a s a b s o r p t io n u n t i l th e c o n s t a n t v a lu e i s r e a c h e d .
T h is i s th e r e g io n in w h ich th e
m easu re d r a t e o f h y d r o g e n a tio n i s d e te rm in e d by th e k i n e t i c s o f th e r e a c t i o n an d n o t by d i f f u s i o n f a c t o r s ( 1 2 ,1 6 ) , I t seem s a l o g i c a l e x te n s io n o f th e p i c t u r e p r e s e n te d b e f o r e t h a t i f t h e r e l a t i v e p e r i o d s o f th e p a r t i c l e o s c i l l a t i o n an d i f th e c a t a l y t i c c y c le can b e a l t e r e d by th e d e c r e a s e in c a t a l y t i c a c t i v i t y , i t may a l s o be changed by s h o r te n in g th e p e rio d o f p a r t ic l e o s c i l l a t i o n .
T his may be a c c o m p lish e d by
i n c r e a s i n g th e fre q u e n c y o f s h a k in g .
S h o r te n in g th e p e r io d o f
p a r t i c l e o s c i l l a t i o n h a s th e e f f e c t o f i n c r e a s i n g th e e f f e c t i v e s u r f a c e a r e a to a p p ro a c h t h a t o f th e t o t a l s u r f a c e a r e a , i n c r e a s i n g th e m e a su re d h y d ro g e n a tio n v e l o c i t y .
G o l* d a n s k ii
and B lo v ic h (16) have fo u n d t h a t th e g r e a t e r th e am ount o f c a t a l y s t , th e g r e a t e r th e fre q u e n c y o f a g i t a t i o n n e c e s s a r y to r e a c h th e k i n e t i c r e g i o n .
T h is i s c o n s i s t e n t w ith o u r m odel
74
w h ich g iv e s a h i g h e r maximum r a t e f o r th e g r e a t e r am ount of c a ta ly s t. I t a p p e a r s t h a t th e l i q u i d volum e e f f e c t an d th e non p r o p o r t i o n a l i t y o f t h e am ount o f c a t a l y s t to th e o b s e rv e d r a t e s o f h y d r o g e n a tio n a r e i n t e r r e l a t e d phenom ena.
They a p p e a r to
o c c u r i n th e r e g io n w h ich c o r re s p o n d s to w h at th e R u s s ia n i n v e s t i g a t o r s c a l l th e d i f f u s i o n r e g i o n .
H ere th e o b se rv e d
k i n e t i c s have no r e l a t i o n to th o s e t r u l y c h a r a c t e r i s t i c o f th e p r o c e s s . Summary A t e n t a t i v e h y p o th e s is h a s b e e n p ro p o se d to e x p l a i n th e change i n h y d ro g e n a tio n r a t e o f s ty r e n e o v e r Raney n i c k e l w ith t o t a l l i q u i d volum e.
I t h a s b e e n shown p o s s i b l e to p r e d i c t
h y d ro g e n a tio n r a t e s w ith c h a n g e s i n th e volum e o f l i q u i d and i n th e amount o f c a t a l y s t .
76
PART IT DBTELOEMBITT A # APPLICATION OF AN EMPIRICAL ..EQUATION FOR HYDROGEN CONSUMPTION The i n i t i a l p o r t i o n o f th e h y d ro g e n a tio n o f s ty r e n e o v e r Raney n i c k e l c a t a l y s t a p p a r e n tly f o llo w s th e e q u a tio n
A • k ^ t^
4
kgt
(1)
w here A i s th e am ount o f h y d ro g en consumed a t tim e t an d k^ and kg a r e c o n s t a n t s .
I f A i s e x p r e s s e d i n p . s . i . an d tim e i n
m in u te s , th e n th e u n i t s o f k^ and kg a r e p . s . i . / m i n . ^ and p .s .i./m in . re s p e c tiv e ly . The s lo p e s o f th e ta n g e n ts to th e c u rv e a lo n g th e i n i t i a l p o r t i o n o f num erous h y d r o g e n a tio n c u r v e s (am ount h y d ro g en consumed v s . tim e ) w ere g r a p h i c a l l y d e te r m in e d .
T hese v a lu e s
when p l o t t e d a g a i n s t tim e showed a l i n e a r o r p r a c t i c a l l y l i n e a r in c re a s e (se e F ig . 2 7 ).
T h e r e f o r e , s e t t i n g up an
e q u a tio n f o r a s t r a i g h t l i n e , we o b ta in
dA/dt = k t w here k i s
+
kg
( a) ,
th e s lo p e o f th e l i n e and k g , th e i n t e r c e p t .
I n t e g r a t i n g , th e n s u b s t i t u t i n g 2 k^ f o r k g iv e s E q u a tio n 1 . The c o n s t a n t s may be d e te rm in e d g r a p h i c a l l y o r by s o l u t i o n o f s im u lta n e o u s e q u a tio n s * The u t i l i t y kg.
o f E q u a tio n 1 l i e s i n th e c o n s t a n ts k]_ and
D i f f e r e n t f a c t o r s a f f e c t one or th e o t h e r , o r b o th
c o n s ta n ts .
I f th e p a r t i c u l a r p r o p e r ty o f th e system to w hich
k% and kg a r e r e l a t e d w ere Imown, th en th e s p e c i f i c e f f e c t o f any f a c t o r can be more c l o s e ly e v a lu a te d by o b s e r v in g c h a n g e s
76
F ig . 27
R e la t io n o f th e I n s ta n ta n e o u s R ate t o Time in th e H y d r o g e n a tio n o f S ty r e n e
o—
d A /d t
1 .5
II
I II III
0
Run 3 9 C -II Run 3 9 A -II Run 4 2 C -I I
10
5
Time —
minutes
77
in
o r kg th a n by th e c h a n g e s I n th e c o n s ta n t r e a c t i o n r a t e
a lo n e . S in c e kg i s d A /d t a t t = 0 , i t I s p ro b a b ly c o n n e c te d w ith th e i n i t i a l c o n d itio n o f th e c a t a l y s t i t s e l f .
T h is i s
c o n s i s t e n t w ith th e id e a t h a t v e ry a c t i v e c a t a l y s t s show h ig h i n i t i a l re a c tio n v e lo c ity .
The r e l a t i o n o f
to th e sy stem
i s n o t d e f i n i t e l y known. From th e d i s c u s s io n i n th e p r e c e d in g p a r t on th e p o s s i b l e i n t e r f e r e n c e o f s o l i d p a r t i c l e s on one a n o th e r , i t may be deduced t h a t i n e r t s o l i d p a r t i c l e s o f th e o r d e r o f th e s i z e o f th e c a t a l y s t p a r t i c l e s may c a u s e a d e c r e a s e in th e h y d ro g e n a tio n r a t e o f s ty r e n e f o r t h e same r e a s o n . r e a l i z e d E o r i t A o r p u m ice. - I n T ab le H
T h is h a s been
i s sum m arized th e
e f f e c t o f th e p r e s e n c e o f i n e r t s o l i d s in th e h y d ro g e n a tio n o f 25 m l. o f s ty r e n e i n 60 m l. o f e th a n o l o v e r Raney n i c k e l c a ta ly s t. T a b le 11 E f f e c t o f I n e r t S o lid s on th e H y d ro g e n a tio n R ate o f S ty re n e Run
2-24A 2-23A* 2-23B* 2-22B 2-210 2-22A
Amount of in e rt s o lid ad d ed none 0 .4 0 0 .5 9 2 .0 0 2 .0 0 7 .0 0
g î* g t* g r g?** e>*
In itia l m ix tu re tem p. 2 4 .4 °G . 2 7 .0 2 4 .8 2 7 .0 2 7 .0 2 6 .8
Room tem p.
2 5 . 0 OO. 2 5 .5 2 5 .2 2 7 .0 2 7 .0 2 6 .8
B la n k ru n c h a rg e c o n s is t e d a b s o lu t e e t h a n o l and a b o u t 0 .6 R i(R )2 -1 0 R . * * H o rit A. H e a te d i n b o i l i n g th e n d r i e d o v e r n ig h t a t llO ^ C . ***?um ice *^H ydrogenation
Maximum ra te p s i. m in.
k, p s i. m in .
2 .1 5 2 .1 5 2 .1 5 1 .9 0 1 .8 0 1 .7 0
0 .1 1 0 .1 1 0 .1 1 0 .1 1 0 .1 2 0 .1 0
kg p s i . m in .
1 .2 1 .2 1 .2 0 .4 2 0 .2 2 0 .2 3
o f 25 m l. s ty r e n e i n 50 m l. o f g . o f Raney n i c k e l d e s ig n a te d d l l . HHOg s o l u t i o n f o r a n h o u r cu rv e s u p e rp o s a b le on 2-24A cu rv e
78
W hile th e p r e s e n c e o f i n e r t s o l i d c a u s e s a r a t e d e c r e a s e , 2 .1 6 p . s . i . / m i n . down to 1 /7 0 p . s . i . / m i n . , i t i s s i g n i f i c a n t t h a t t h i s d e c r e a s e i s acco m p an ied by a d e c r e a s e i n th e v a lu e o f kg w h ile t h a t o f k ^ re m a in s a b o u t c o n s t a n t .
The c o n s ta n t
k]^ re m a in e d a p p ro x im a te ly 0 ,1 1 p . s . i . / m i n . ^ w h ile kg d ro p p ed from 1 ,2 0 p . s . i . / m i n . to 0 .2 2 p . s . i . / m i n . E x p e rim e n ta l c o n d i ti o n s may be ch o sen so a s to k eep kg c o n s t a n t and to b r i n g a b o u t c h a n g e s in k ^ .
F o r an i l l u s t r a t i o n
o f t h i s we a r e u s in g d a ta w h ich w ere u s e d in show ing th e e f f e c t o f l i q u i d volume on th e h y d ro g e n a tio n r a t e o f s ty r e n e o v e r Raney n i c k e l .
H ere i t was shown t h a t i n c r e a s i n g th e volum e
i n c r e a s e d th e r a t e o f h y d r o g e n a tio n .
I n T a b le 18, i t s h o u ld
be o b se rv e d t h a t a lo n g w ith th e i n c r e a s e in th e maximum r a t e , th e v a lu e o f k ^ i n c r e a s e s w h ile t h a t o f kg re m a in s a b o u t c o n s ta n t. T ab le 12 E f f e c t o f L iq u id Volume on th e H y d ro g e n a tio n R ate o f S ty re n e Run
95B 940 95A 2-5A 94-Bl
Amount of S ty re n e
In itia l m ix tu re tem p.
25 m l. 35 SO 60 75
2 6 .8 % . 29.6 27.8 27.4 26.1
Room tem p. 27.cPc. 26.0 2 6 ,8 25.5 26.0
Maximum ra te p s i. m in . 0.90 1.15 1.45 1.90 2.25
^1 281.. m in. 0.019 0.031 0.050 0 .0 6 3 0.091
kp p s i ^ min 0.47 0.61 0.55 0.59 0.56
A bout 1 .2 g . o f Raney n i c k e l d e s ig n a te d H i(R )1 -7 3 . A p l o t o f th e v a lu e s o f k^^ a g a i n s t th e volum e o f s ty r e n e g iv e s a s t r a i g h t l i n e .
T h is i n d i c a t e s t h a t k^ i s r e l a t e d to
79
some a d d i t i v e p r o p e r ty o f th e sy stem ( F ig . 2 8 ) . F u r t h e r i n v e s t i g a t i o n i s n e c e s s a r y to e s t a b l i s h c o n c lu s iv e ly th e r e l a t i o n o f th e v a r i o u s A c t o r s w hich can i n f lu e n c e th e r a t e o f h y d r o g e n a tio n an d t h e two c o n s t a n t s ,
and k g .
I t does
seem r e a s o n a b le and p l a u s i b l e t h a t kg i s c o n n e c te d w ith th e c o n d i t i o n o f th e c a t a l y s t .
80
F ig . 28
R e la t io n o f k% t o T o ta l L iq u id Volume
1.00
0.50
25
50 L iq u id Volume —m l.
75
61
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V IT A
Y o sM k azu Yamada was b o rn i n H onokaa, H aw aii on May 8 0 , 1 9 1 5 .
He r e c e iv e d a B .S . d e g re e fro m th e U n i
v e r s i t y o f H a w a ii, H o n o lu lu , T. H . , i n June, 1937 and a n M .S. d e g r e e from th e H orace H. Rackham S c h o o l o f G ra d u a te S t u d i e s , U n i v e r s i t y o f M ic h ig a n , i n Ju n e 1 9 3 8 . He h a s a l s o s t u d i e d d ra w in g and p a i n t i n g a t th e C o lle g e o f A r c h i t e c t u r e , U n i v e r s i t y o f M ic h ig a n .
D u rin g th e
w ar he w as s t a t i o n e d lo n g enough a t B r is b a n e , A u s t r a l i a t o a t t e n d s e s s i o n s a t t h e (Q ueensland U n i v e r s i t y o f th a t c ity . He i s a member o f P h i Lambda U p s ilo n .