Chakrabarti 1993 Reactive-Polymers

7/24/2019 Chakrabarti 1993 Reactive-Polymers

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Reactive Polymers 2 0 (1 9 9 3 ) 1 -4 5 1

E l s e v i e r S c i e n c e P u b l i s h e r s B . V . , A m s t e r d a m

State of the Art Report

C a t i o n i c i o n e x c h a n g e r e s i n s a s c a t a l y s t

A n i m e s h C h a k r a b a r t i a n d M . M . S h a r m a *

Department of Chemical Technology University of Bom bay Matunga Bombay-400 019 India

( R e c e i v e d N o v e m b e r 2 5, 1 9 92 ; a c c e p t e d F e b r u a r y 2 , 1 99 3)

b s t r a c t

Th is paper prese nts a review of the l i te ra tu re pe r ta in ing to ca ta lysis by ca tion exchange

re s ins . Emp has i s ha s been g iven to the l i t e ra tu re tha t ha s ap pea red du r ing the l a s t seven

years . A var ie ty of reac t ions ca ta lyzed by ca t ion exchange resins have been tabula ted

according to the i r broad c lass if ica tion; indust r ia l ly im porta nt rea c t ions have bee n de l in-

ea ted . Examples , where the use of ion exchange resin ca ta lysis has led to an improvement

in the se lec tiv i ty of the desi red products , h ave a lso been d iscussed . App roach es for the

in te rp re t a t ion o f k ine t ic da ta and mode l ing have been rev iewed .

The type o f r eac to r to be employed fo r c a r ry ing ou t ion exchange re s in ca t a lyzed

reac t ions ha s been d i scussed . A new em erg ing a rea i s t he adop t ion o f d i s ti l la t ion co lumn

reac tors e . g . , methy l t e r t - b u t y l e the r f rom i sobu ty lene and me thano l .

Some a spec t s o f the deac t iva t ion and regene ra t ion o f the se ca t a lys t s have been b r i e f ly

discussed.

The use o f ion exchange re s ins fo r the remova l o f impur i t i e s f rom mix tu re s and the

separa t ion of c lose-boi l ing compounds by explo i t ing the i r d i f fe rent c h em i c a l reac t iv ity has

been h igh l igh ted .

Sugges t ions have been mad e fo r fu r the r work .

Keywords: ca ta lysis ; ca t ion exchange resin ; a lkyla t ion; e ther i f ica t ion; es te r i f ica t ion; Am-

berlyst-15

C o n t e n t s

A b s t r a c t 1

1 . I n t r o d u c t i o n 2

2 . P r e v i o u s r e v i e w s 3

3 . P r e p a r a t i o n o f i o n e x c h a n g e r e s i n c a t a l y s t s 3

4 . R e s i n s t r u c t u r e a n d i t s c a t a l y t ic c o n s e q u e n c e s 4

* C o r r e s p o n d i n g a u t h o r .

0 9 2 3 - 1 1 3 7 / 9 3 / 0 6 . 0 0 1 99 3 - E l s e v i e r S c i e n c e P u b l i s h e r s B . V . A l l r i g h t s r e s e r v e d


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2 A. Chakrabarti, M.M. Sh arm a/R eac t. Polym. 20 1993) 1-4 5

5. Catalysis by ion exchange resins 5

6. Adv antages and limitations of ion exchange resins as catalyst 6

7. Selectivityof ion exchange resin catalysts 7

8. Kinetics of ion exchange resin catalysis 8

8.1. Role of ma ss transfer 8

8.2. Kinetic mod el 9

8.3. Dis tribution coeffic ient 11

9. Reactions catalyzed by cation exchange resins: Reactions of industrial importance 12

10. Reactors used for ion exchange resin catalyzed reactions 22

11. So m e important observations on ion exchange resin catalysis 23

12. Separation of close-boilingcom pounds through reactions catalyzed by ion exchange resin 25

13. Rem oval of impurities from a mixture by reaction catalyzed by ion exchange resin 26

14. M odified ion exchange resin s and supported perfluorinated resin sulfonic acid 27

15. Deactivation and regeneration of ion exchange resin catalysts 29

16. I on exchan ge resin s versus clays versus othe r catalysts 30

17. Co nclus ions 31

18. Futu re scop e 32

References 32

1. I n t r o d u c t i o n a c id s , b u t t h e u s e o f a c i d i o n e x c h a n g e r e s i n

p r o v i d e d r e a s o n a b l y h i g h r e a c t i o n r a t es a t

A n i o n e x c h a n g e m a t e r i a l m a y b e b r o a d l y t h e lo w t e m p e r a t u r e s e m p l o y e d [ 3 ]. I n t h e

d e f i n e d a s a n i n s o lu b l e m a t r i x c o n t a i n i n g c a s e o f d e h y d r a t i o n o f t e r t - b u t a n o l , s u l f o n i c

l a bi le i o n s c a p a b l e o f e x c h a n g i n g w i t h i o n s i n a c i d re s i n c at a ly s ts w e r e f o u n d t o b e m u c h

t h e s u r r o u n d i n g m e d i u m w i t h o u t m a j o r p h y s - m o r e e f f ec t iv e t h a n t h e s o l u b l e a c i d c a ta l ys t s

i ca l c h a n g e t a k i n g p l a c e i n i ts s t r u c t u r e . T h e [ 4] . S i m i l a rl y , a c t i v it i e s h i g h e r t h a n s o l u b l e

r e si n s t yp ic al ly e m p l o y e d a r e su l fo n i c a c id p - t o l u e n e s u l f o n i c a c id p - T S A ) h a s b e e n r e-

c a t i o n e x c h a n g e r s i n t h e h y d r o g e n f o r m o r p o r t e d f o r t h e a d d i t i o n o f a l c o h o l s t o o l e f in s

q u a t e r n a r y a m m o n i u m a n i o n e x c h a n g e r s i n u s i n g i o n e x c h a n g e r e s i n c a ta l ys t s [ 5] . F o r t h e

t h e h y d r o x i d e f o r m . T h e i d e a t h a t i o n e x - e t h e r i f i c a t io n o f e t h y l e n e a n d p r o p y l e n e g ly -

c h a n g e r s c a n b e u s e d a s a s u b s t i t u t e fo r c o ls w i t h i s o b u t y l e n e , i t w a s o b s e r v e d t h a t

m i n e r a l a c i ds a n d b a s e s , d a t e s b a c k t o 1 91 1 t h e r a t e s o f r e a c t i o n w i t h c a t i o n e x c h a n g e

[1 ]. T h e f ir s t c o m m e r c i a l p r o c e s s , f o r e s t er i fi - r e s i n c at a ly s t w e r e m u c h h i g h e r t h a n t h o s e

c a t i o n a n d e s t e r h y d r o ly s i s o v e r W o f a t i t p h e - w i t h s o lu b l e p - T S A c a t a ly s t [ 6 ]. I n t h e c a se

n o l s u l p h o n i c a c i d - f o r m a l d e h y d e c o n d e n s a - o f e t h e ri f ic a t io n o f t h e p h e n o l s w i t h i so b u ty -

t i o n p o l y m e r s , w a s d e v e l o p e d b y I . G . F a r - l e n e , t h e y i e ld s o f t h e c o r r e s p o n d i n g t e r t -

b e n i n d u s t r i e in t h e 1 9 40 s i n t h e c o n t e x t o f b u t y l e t h e r s w e r e r e m a r k a b l y h i g h c o m p a r e d

t h e G e r m a n w a r ef f o rt [ 2 ]. A l t h o u g h io n t o t h a t w i t h p - T S A [7a]. B e c a u s e o f t h e

e x c h a n g e c a ta l ys is i n v ol v e s t h e u s e o f i o n i m p r o v e d s e l e c ti v it y o f t h e i o n e x c h a n g e

e x c h a n g e r e si n s t o p r o m o t e r e a c t i o n s t h a t r e si n s , t h e c u r r e n t i o n e x c h a n g e r e s i n c a t a-

a r e n o r m a l l y c a t a ly z e d b y m i n e r a l a c i d s a n d l ys t c a p a c i ty o f a b o u t 4 00 0 m 3 / y r o f r e s i n i s

b a s e s, t h e r e a r e m a n y i n s t a n c e s w h e r e t h e e x p e c t e d t o d o u b l e o v e r t h e n e x t f iv e y e a r s,

u s e o f i o n e x c h a n g e r e s i n c a ta l y st s h a s l e d t o e s p e c ia l l y d u e t o t h e i r h i g h c o n s u m p t i o n i n

i m p r o v e d a ct iv it y a n d / o r y i el d o v e r t h e h o - m e t h y l t e r t - b u t y l e t h e r M T B E ) p l a n t s [7 b].

m o g e n e o u s c a ta l ys ts . F o r t h e r e a c t i o n o f l in - T h i s p a p e r t a k e s i n t o c o n s i d e r a t i o n a ll t h e

e a r k e t o n e s a n d a l c o h o ls t o g i ve k e t al s , t h e p r e v i o u s r e v ie w s w h i c h h a v e a p p e a r e d i n t h e

r a t e s w e r e i m p r a c t i c a b l y l o w w i t h t h e s o l u b l e l i t e ra t u r e . I n t h is r e v ie w , e m p h a s i s h a s b e e n


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A. Chakrabarti, M.M. Sharma /Re ac t. Polym . 20 1993) 1-45 3

e s p e c i a ll y g i v e n t o t h e l i te r a t u r e o f t h e l a st t a g e t h a t t h e d e g r e e o f c r o s s li n k i n g a n d t h e

s e v e n y e a rs . A n a t t e m p t h a s b e e n m a d e t o p a r t i c l e s i ze o f t h e re s i n s a r e m o r e re a d i l y

f o c u s a t t e n t i o n o n i m p o r t a n t a s p e c t s o f c a t a l- a d j u s t e d [ 16 ].

y s is b y i o n e x c h a n g e r e s in s . T h e n e w d e v e l - T h e m o s t i m p o r t a n t r e s i n s o f t h is t y p e a r e

o p m e n t s i n p r e p a r i n g t a i l o r - m a d e r e s i n c a t a - c r o s s l i n k e d p o l y s t y re n e s w i t h s u l fo n i c a c id

l ys ts h a v e a l so b e e n d i s c u ss e d . T h e u s e o f g r o u p s w h i c h h a v e b e e n i n t r o d u c e d a f t e r

c a t i o n e x c h a n g e r e s i n s f o r a v a r i e ty o f a c i d- p o l y m e r i z a t i o n b y t r e a t m e n t w i t h c o n c e n -

c a t a l y z e d r e a c t i o n s h a s b e e n c o v e r e d ; s p e c ia l t r a t e d s u l fu r ic a c i d o r c h l o r o s u l f o n ic a c i d

a t t e n t io n h as b e en g iv en to in d u s t r i a l ly im- [1 7 -1 9 ]. A s a ru l e , d iv in y lb en z en e i s u sed as

p o r t a n t r e a c t io n s . T h e p o t e n t i a l o f e x p e n s i v e t h e c r o s s li n k i n g a g e n t ( c o m m e r c i a l m i x t u r e

p e r f l u o r i n a t e d s u lf o n ic a c i d b a s e d i o n e x - o f d i v i n y l b e n z e n e a n d e t h y l s t y r e n e i s u s e d

c h a n g e r e s i n a s s u p p o r t e d c a t al y st s h a s b e e n f o r t h is p u r p o s e ) .

c o n s i d e r e d . T h e c o p o l y m e r b e a d s a r e p r e p a r e d b y t h e

s o - c a l l e d p e a r l p o l y m e r i z a t i o n t e c h n i q u e

[2 0,2 1]. T h e m o n o m e r s ( f r o m w h i c h p o l y m e r -

2.

Previous reviews

i z a t i o n i n h i b i t o r s h a v e b e e n r e m o v e d ) a r e

m i x e d a n d a p o l y m e r i z a t i o n c a ta l y st s u c h a s

B h a g a d e a n d N a g e s h w a r h a v e p u b l i s h e d b e n z o y l p e r o x i d e is a d d e d . T h e m i x t u r e is

r e v ie w s o n d i f f e r e n t r e a c t i o n s, n a m e l y , hy - t h e n a d d e d t o a t h o r o u g h l y a g i t a t e d a q u e o u s

d r a t i o n , d e h y d r a t i o n , e s t e r i fi c a t i o n , e s t e r h y - s o l u t i o n w h i c h is k e p t a t t h e t e m p e r a t u r e

d ro lys i s an d a lk y la t io n , ca t a ly zed b y io n ex - r eq u i re d fo r p o ly m er i za t io n (u su a l ly 8 5 to

ch a n g e r es in s [8 -1 2 ] . In a l l t h e cases , t h ey 1 00 C ). T h e mix tu re fo rm s smal l d ro p le t s

h a v e t a b u l a t e d t h e r e a c t a n t s a n d t h e c a t al y st w h i c h r e m a i n s u s p e n d e d . A s u s p e n s i o n s t a bi -

u sed . W id d ec k e [1 3 ], i n an ex h au s t iv e r ev iew , l i ze r (g e l a t in , p o ly v in y l a l co h o l , so d iu m

h a s d i s c u s s e d t h e w o r k i n g c o n c e p t s o f i o n

e x c h a n g e r e s i n s a s c a ta l ys t . S o m e i m p o r t a n t o l e a t e , s o d i u m m e t h a c r y l a t e , m a g n e s i u m s il i-

p o i n t s a b o u t t h e d e s i g n a n d i n d u s t r ia l a p p li - c a t e ,

e t c .

i n t h e a q u e o u s p h a s e p r e v e n t s

a g g l o m e r a t i o n o f t h e d r o p l e t s . T h e s i ze o f

c a t i o n s o f t h e c a ta l y st s h a v e a ls o b e e n h i g h - t h e d r o p l e t s d e p e n d s c h i e fl y o n t h e n a t u r e o f

l ig h te d b y h im . R ec en t ly , N e ie r [1 4 ] h as p u b - th e su sp e n s io n s tab i l i ze r, v i scos i ty o f t h e so -

l i s h e d a c o m p r e h e n s i v e r e v i e w o n t h e i o n

l u t io n , a n d a g i t a t io n a n d c a n b e v a r i e d w i t h in

ex ch an g er s a s ca t a ly s t . O lah e t a l . [ 1 5 ] h a v e w i d e l im i ts . T h e p o l y m e r i s o b t a i n e d i n t h e

p u b l i s h e d a r e v i e w a r t ic l e o n p e r f l u o r i n a t e d f o r m o f f a ir ly u n i f o r m s p h e r i c a l b e a d s . F o r

su l fo n ic ac id r e s in ca t a ly zed reac t io n s . T h e mo s t p u rp o se s , a b e ad s i ze o f 0 .4 to 1 .1 m m

p r e s e n t r e v i e w c o v e r s s o m e a d d i t i o n a l a n d is p r e f e r r e d , b u t b e a d s f r o m 1 ~ m to 2 m m

n e w a s p e c t s o f c a ta l ys i s a n d a ls o h i g h l ig h t s i n d i a m e t e r c a n b e p r e p a r e d w i t h o u t m a j o r

m a n y o f t h e i n d u s t ri a l ly i m p o r t a n t r e a c t i o n s .

d i f f i cu l t i e s . P o ly mer i za t io n in aq u eo u s su s -

p e n s i o n i s p o s s i b l e i f t h e m o n o m e r s a r e i n -

3. Preparat ion of ion exchange res in cata so lu b le in w a te r . T h i s is n o t a lw ay s th e case .

lysts H o w e v e r , w a t e r - s o l u b l e m o n o m e r s s u c h a s

ac ry l i c ac id can b e mad e in so lu b le , fo r ex am-

M o s t p r e s e n t d a y i o n e x c h a n g e r e s i n s a r e p i e , b y e s t e r if i c a t io n . T h e e s t e r g r o u p s a r e

a d d i t i o n c o p o l y m e r s p r e p a r e d f r o m v i n yl t h e n h y d r o l y z e d a f t e r p o l y m e r i z a t i o n . A l t e r -

m o n o m e r s . T h e s e p o l y m e r s h a v e a h i g h e r n a t iv e ly , t h e w a t e r - i n - o i l t e c h n i q u e ( in -

c h e m i c a l a n d t h e r m a l s t a bi li ty t h a n t h e i r v e r s e s u s p e n s i o n p o l y m e r i z a t i o n ) c a n b e

f o r e r u n n e r s , t h e c o n d e n s a t i o n p o l y m e r s , u s e d . H e r e , t h e c o p o l y m e r i s f o r m e d e x c lu -

A l s o , a d d i t i o n p o l y m e r i z a t i o n h a s t h e a d v a n - s iv e ly f r o m h y d r o p h i l i c m o n o m e r s . T h e


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4 A. Chakrabarti, M.M. Sharma/React. Polym. 20 1993) 1-45

d r o p l e t s o f th e p o l y m e r i z a t i o n m i x t u r e a r e u n i f o r m s iz e . I f s u i t a b le m e t h o d s a r e u s e d t o

s u s p e n d e d i n a n i n e r t o r g a n i c s o l v e n t in p r e v e n t t h e m f r o m c o a l e s c i n g t o f o r m l a r g e r

w h i c h t h e m o n o m e r s a r e i n so l u bl e , d r o p l et s , m o n o d i s p e r s e b e a d s a r e f o r m e d ,

T h e p o l y m e r i z a t i o n p r o c e d u r e d e s c r i b e d y i e l d i n g m o n o d i s p e r s e r e s in s a f t e r f u n c t i o n -

a b o v e is g e n e r a l l y a d o p t e d f o r m a n u f a c t u r i n g a l iz a t io n . U s i n g t h e p r o c e s s d e v e l o p e d b y

g e l -t y p e r e si n s. H o w e v e r , t h e c o n v e n t i o n a l B a y e r A G , L e v e r k u s s e n , i t is p o s s ib l e t o p r o -

p e a r l p o l y m e r i z a t i o n t e c h n i q u e c a n b e s u it - d u c e b o t h g e l a n d m a c r o p o r o u s r e s in s . F o r

a b ly m a n i p u l a t e d t o g e t h i g h l y p o r o u s , t h e m o n o d i s p e r s e r e s i n t h e r e i s n o G a u s s i a n f r e -

s o - c a ll e d m a c r o r e t i c u l a r o r m a c r o p o r o u s , i o n q u e n c y d i s t ri b u t io n . T h u s , m o n o d i s p e r s e

e x c h a n g e r e si n s . A n o r g a n i c s o l v e n t w h i c h is r e f e r s t o p r o d u c t s w h e r e a t l e a s t 9 0 % o f a ll

a g o o d s o l v en t f o r t h e m o n o m e r s , b u t a p o o r b e a d s a r e o f t h e s a m e s iz e w i t h a t o l e r a n c e

s o l v en t f o r t h e p o l y m e r , is a d d e d to t h e p o ly - o f + 0 .1 m m . H o w e v e r , t h e b e a d s a r e u s u a l ly

m e r i z a t i o n m i x t u r e . A s p o l y m e r i z a t i o n p r o - w i t h i n a n e v e n n a r r o w e r t o l e r a n c e ,

e.g.

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g r o w i n g c o p o l y m e r r e g i o n s. I n t h is W a y , o n e A n o t h e r t y p e o f i o n e x c h a n g e r e s in ,

c a n o b t a i n s p h e r i c a l b e a d s w i t h w i d e p o r e s n a m e l y , p e r f l u o r i n a t e d s u l fo n i c a c i d re s i n

( s e v e ra l h u n d r e d A n g s t r o m u n i t s) w h i c h a l- ( N a t i o n ) , i s p r e p a r e d fr o m a c o p o l y m e r o f

l o w a c c e ss t o t h e i n t e r i o r o f t h e r e s i n e v e n t e t r a f l u o r o e t h e n e a n d p e r f l u o r o [ 2 -( f l u o r o -

w h e n n o n - p o l a r s o l v e n t s a r e u s e d [ 22 ]. s u l f o n y le t h o x y ) ] p o ly v i n y l e t h e r . T h e p e r f l u o -

T h e s u lf o n a t i o n o f t h e r e s in s p r e s e n t s n o r i n a t e d v i ny l e t h e r i s p r o d u c e d by r e a c t i n g

p r o b l e m s i f p r o p e r p r e c a u t i o n s a r e t a k e n , t e t r a f l u o r o e t h e n e w i t h S O 3 t o f o r m a c y c li c

S u l f o n a t i o n p ro g r e s s e s f r o m t h e o u t e r s h e ll s u l f o n e w h i c h s u b s e q u e n t l y r e a r r a n g e s t o f lu -

t o w a r d s th e c e n t r e o f t h e p a r t i c le a n d is o r o c a r b o n y l m e t h a n e s u lf o n y l f l u o r id e . T h e

a c c o m p a n i e d b y c o n s i d e r a b l e s w e l li n g a n d l i n e a r a n a l o g r e a c t s w i t h t w o m o l e s o f h e x a -

e v o l u t i o n o f h e a t . T h e m a t r ix is s t r a i n e d f l u o r o p r o p y l e n e o x i d e t o y i e l d a c o m p o u n d

r a t h e r s e v e re l y , a n d t h e b e a d s m a y c r a c k , w i t h a t e r m i n a l 1 - f l u o r o c a rb o n y l t r if l u o r o -

S u c h d i s i n t e g r a t i o n c a n b e a v o i d e d b y l e t ti n g e t h o x y g r o u p . T h i s g r o u p l o s es c a r b o n y l f l uo -

t h e b e a d s s w e ll , p r i o r t o s u l f o n a t io n , i n s o l- r i d e o n h e a t i n g w i t h N a 2 C O 3 t o g i v e t h e

v e n t s s u c h a s t o l u e n e , n i t r o b e n z e n e , m e t h y l - p e r f l u o r i n a t e d v in y l e t h e r . T h e c o p o l y m e r

e n e c h l o r i d e o r t r i c h l o r o e t h a n e [1 9]. S i m i l a r r e s i n i n t h e s u l f on y l f l u o r i d e f o r m i s b a s e

s t ra i n s d e v e l o p w h e n t h e s u l f o n a t e d b e a d s h y d r o l y z e d t o t h e a l k al i f o r m a n d t h e n a c id i -

a r e t r a n s f e r r e d i n t o a d i l u t e a q u e o u s s o l u t i o n f l e d t o t h e s u l f o n i c a c i d f o r m [2 4].

o r p u r e w a t e r . T h e r e f o r e , i t i s a d v i s a b l e t o

t r a n s f e r t h e b e a d s a t f i rs t i n t o a h i g h l y c o n -

c e n t r a t e d e l e c t r o l y t e s o l u t io n w h i c h c a u s e s 4 . R e s i n s t r u c t u r e a n d it s c a t a l y ti c c o n s e -

l es s s w e l li n g , a n d t h e n t o d i l u t e t h e s o l u t io n q u e n e e s

prog ress ive ly [19].

T h e c o m m e r c i a l r e s in s a v a i la b l e a r e h e t - T h e r e s in s c a n b e d i v i d e d i n t o t w o g r o u p s

e r o d i s p e r s e a n d h a v e p r o p e r t i e s w h i c h c a n h a v i n g m a j o r s t r u c t u r a l d i f f e r e n c e s , g e l a n d

b e a t t r i b u t e d d i r e c tl y t o t h e b a n d w i d t h , m a c r o r e t i c u l a r r e s in s . O n a m i c r o s c o p i c

w i t h i n w h i c h t h e b e a d s iz e s f al l. T h e s e i r re g - s c a le , t h e t h r e e - d i m e n s i o n a l p o l y m e r i c g e l

u l a r it i e s c a n b e o b s e r v e d i n t h e m e c h a n i c a l m a t r i x i s h o m o g e n e o u s w i t h n o d i s c o n t i n u -

s t a b il i ty , h y d r a u l i c p r o p e r t i e s , a n d k i n e t i c i t ie s . I f t h e g e l b e a d s a r e t o t a l l y d r y , t h e n t h e

p h e n o m e n a i n c o l u m n s [2 3]. p o l y m e r i c m a t r i x c o l la p s e s a n d t h e p o ly s ty -

I n t h e p a s t f e w y e a r s i t h a s b e e n p o s s ib l e r e n e c h a i n s w i l l b e as c l o s e a s a t o m i c f o r c e s

t o d i s p e r s e l i q u id m o n o m e r s i n t o d r o p l e t s o f a l lo w . I n t h is c o n d i t i o n , u n l e s s a r e a c t a n t i s


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i t s e l f c a p a b l e o f s w e l l in g t h e m a t r ix , t h e c o l- m e d i u m a n d p r e s e n t u n i f o r m l y t h r o u g h o u t

l a p s e d g e l b e a d e x h i b it a l m o s t n o c a ta l y ti c t h e s ys t e m . T h i s i s n o t t h e c a s e w i t h r e s i n

ac t iv i ty b ec au se o n ly th e s i t e s o n th e b ea d ' s ca t a ly s i s. T h e ca ta ly t i ca lly ac t iv e g ro u p s a re

s u r f a c e ( w h i c h a r e i n s i g n if i c a n t i n n u m b e r a n c h o r e d t o t h e m a t r i x a n d , i n t h e s o l v e n t -

c o m p a r e d t o t h e t o t a l a c t iv e s i te s w i t h i n t h e r e s i n s y s te m , a re l o c a t e d a t t h e s u r fa c e o f

b o d y o f t h e b e a d ) a r e a v a il a b le t o t h e re a c - a n d w i th i n t h e b o d y o f t h e r e s in b e a d o n l y.

t a n t s [ 2 5 ]. T h e r e f o r e , t h e s w e l l i n g a b il it y o f T h e b u l k s o l u t i o n i s c o m p l e t e l y f r e e o f c a t a -

th e r eac t a n t s i s a p re r eq u i s i t e fo r ca t a ly s i s b y lys t an d co n seq u en t ly ca t a ly ti ca l ly in e r t .

g e l re s i n s. G e l r e s i n s a r e c h a r a c t e r i z e d b y H o w e v e r , i n p o l a r s o l ve n t s , a c i d l e a c h i n g m a y

d i v i n y l b e n z e n e c o n t e n t g e n e r a l l y b e l o w 1 2 % . b e o b s e r v e d l e a d i n g t o t h e p r e s e n c e o f c a t -

T h e l im i t a t io n o f t h e g e l r e s in s w as l a rg e ly a ly ti ca lly ac t iv e sp ec ies in th e b u lk so lu t io n

o v e r c o m e , a r o u n d 1 9 60 , w i t h t h e a d v e n t o f a s w e l l a s i n t h e r e s in .

t h e m a c r o p o r o u s i o n e x c h a n g e r e s i ns [ 2 6 - I o n e x c h a n g e r s a r e , i n e f f e c t, p a r t i c u l a t e

3 0] . T h e y co n s i s t o f ag g lo m era te s o f v e ry ac t iv e sp ec ies an d w h e n u se d as ca t a lys t s

s m a l l m i c r o s p h e r e s i n t e r s p e r s e d w i t h m a c r o - o f f e r t h e c h e m i c a l b e n e f i t s o f h o m o g e n e o u s

p o r e s . R e a c t a n t s m a y m o v e e a s il y i n t o th e c a ta l ys is c o m b i n e d w i t h t h e p h y s ic a l a n d m e -

i n t e r i o r o f t h e b e a d t h r o u g h t h e s e m a c r o - c h a n i c a l b e n e f i t s o f h e t e r o g e n e o u s c a ta l ys t s

p o res . T h e s ig n i f i can t co n seq u e n ce i s t h a t , [25 ].

w h e r e a s g e l r e s i n s c a n o n l y f u n c t i o n e f f e c - D e p e n d i n g o n t h e n a t u r e o f t h e r e a c t a n t s

t iv e ly a s ca t a ly s ts i n a sw e l l in g m ed iu m , mac - an d so lv en t , a l l t h e r e s in -ca t a ly ze d r eac t io n s

r o r e t i c u l a r r e s i n s c a n f u n c t i o n a l so i n n o n - f a ll in t o o n e o f t w o m a j o r ty p e s , n a m e l y ,

s w e l li n g s o l ve n t s, t h e r e b y g r e a t l y e x p a n d i n g T y p e A a n d T y p e B [ 2 5 ] . T y p e A c a n b e

th e p o ss ib i l i ti e s o f r e s in ca t a lys i s [3 1 -3 4 ]. su b d iv id ed in to tw o g ro u p s : (A 1 ) ca t a ly s i s b y

f u ll y w a t e r - s w o l l e n r e s i n s i n a q u e o u s s y s te m s

a n d ( A 2 ) ca ta ly si s in m i x e d w a t e r / o r g a n o

5 . C a ta ly s i s b y io n ex ch an g e r es in s so lv en t s. In th e f i rs t case , t h e h y d ra t ed p ro -

to n i s t h e ca t a ly t i c ag en t an d th e r e s in i s

T h e p r i n c i p a l d i f f e r e n c e s b e t w e e n c a ta l y- f o u n d t o b e m o r e e ff e c t iv e t h a n h o m o g e -

s is b y d i s so lv ed e l ec t ro ly t es an d b y r es in s a re : n eo u s ac id . D av i s an d T h o m as [37 ] sh o w e d

i )

w i th r e s in s a s ca ta ly s ts , t h e ca t a ly s i s t h a t t h e r e s in -ca t a ly ze d h y d ro ly s is o f a se r i e s

o v e r l a p s w i t h d i f fu s i o n , a d s o r p t i o n a n d d e - o f e s t e r s u s i n g p u r e w a t e r a s a s o l v e n t w a s

s o r p t i o n p r o c e s s e s [ 3 5 ]; a n d t h e c o n c e n t r a - m o r e e f f e c t i v e t h a n h y d r o c h l o r i c a c i d .

t i o n o f t h e r e a c t a n t s i n s i d e t h e c a t al y s t ( w h e r e H a s k e l l a n d H a m m e t t [3 8] u s e d 7 0 % a c e t o n e

t h e r e a c t i o n t a k e s p l a c e ) m a y b e d i f f e r e n t a s t h e s o l v e n t i n t h e h y d r ol y s is o f d i f f e r e n t

f r o m t h a t i n t h e b u l k s o l u ti o n , d e p e n d i n g o n e s t e r s c a t a l y z e d b y i o n e x c h a n g e r e s i n a s t h e

t h e n a t u r e o f t h e m a t r i x, fi x e d i o n i c g r o u p , c a t al y st ( T y p e A 2 ) a n d f o u n d t h a t h y d r o c h l o -

t h e r e a c t a n t s , a n d t h e s o lv e n t s. F o r a p a r t ic u - r ic a c i d w a s m o r e e f f i c ie n t t h a n t h e r e s in .

l a r c a t a ly s t a n d r e a c t a n t s y s te m , t h e d i s tr i b u - H e r e t h e p r e s e n c e o f a c e t o n e c h a n g e s t h e

t i o n o f t h e r e a c t a n t s b e t w e e n t h e r e s i n p h a s e d i s t r ib u t i o n o f t h e e s t e r i n f a v o u r o f t h e b u l k

a n d t h e b u l k s o l u t i o n m a y b e c h a n g e d b y s o l u t i o n w h i c h i s r i c h i n a c e t o n e (i o n e x -

c h a n g i n g t h e s o l v e n t [3 6]. c h a n g e r i s e n r i c h e d b y w a t e r d u e t o i ts h i g h e r

i i )

t h e m a t r i x w i t h t h e f i xe d i o n i c g r o u p d i e l e c t r ic c o n s t a n t ) l e a d i n g t o a l o w e r e f fi -

m a y h a v e s o m e i n f l u e n c e ( w h i c h i s n o t p u r e l y c i e n c y o f t h e re s i n . T h e a b o v e d i s c u s si o n a l so

p h y s ic a l ) o n t h e c o u r s e o f t h e r e a c t i o n , s h o w s t h e i m p o r t a n c e o f r e a c t i o n c o n d i t i o n s

In h o m o g en eo u s ca t a ly s i s, t h e ca t a ly t i ca lly in ach iev in g su ccess in r e s in ca t a ly s i s. T y p e B

ac t iv e sp ec ies is d i s so lv ed in th e r eac t io n i s d iv id ed in to tw o su b g ro u p s : (B 1 ) ca t a ly s i s


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6 A. Chakrabarti , M.M . Sha rma /React . Polym. 20 1993) 1-4 5

b y w a t e r - f r e e ) r e s in s i n n o n - a q u e o u s sy s- c a p i t a l a n d p r o c e s s i n g c o s ts b y e l i m i n a t i n g

t e m s w h e r e w a t e r is n o t a p r o d u c t o f t h e t h e s te p s a n d e q u i p m e n t r e q u i r e d f o r c a t a-

r e a c t i o n a n d B 2 ) n o n - a q u e o u s c a ta l y si s i n l ys t r e m o v a l i n a n a l o g o u s h o m o g e n e o u s p r o -

w h i c h w a t e r i s a b y - p r o d u c t o f r e a c t i o n , c e s se s . T h e w a s t e d i s p o s al p r o b l e m i s o b v i-

A l k y l a t i o n o f p h e n o l w i t h o l e f in s is a t y p ic a l a t e d . P r o d u c t p u r i ty a n d y ie l d a r e im p r o v e d

e x a m p l e o f t h e B l - t y p e r e a c t i o n . W a t e r h a s a i n m a n y c a s es . R e s i n s c a n o f t e n b e u s e d , i n

d e t r i m e n t a l e f f e c t o n th e B l - t y p e r e a c t i o n s h u n d r e d s o f c a t a ly t ic c y c le s w i t h o u t r e g e n e r -

w h i c h a r e c a ta l y z e d b y u n d i s s o c i a t e d s ul - a t i o n i n w e l l - d e s i g n e d p r o c e s s es . T h e r e f o r e ,

f o n i c a c i d g r o u p s ) . T h e c a u s e f o r t h e d e t r i - t h e c o s t o f t h e r e s i n i s s p r e a d o v e r t h e l if e o f

m e n t a l e f f e c t o f w a t e r o n B l - t y p e r e a c t i o n t h e r e s in , m a k i n g t h e c a t al y s t c o s t p e r u n i t

w a s g i ve n b y Z u n d e l [3 9]. W a t e r c o m p e t e s p r o d u c t i o n l o w e r t h a n t h e i r h o m o g e n e o u s

w i t h t h e r e a c t a n t f o r t h e a c t iv e s i te s a n d is c o u n t e r p a r t i n r e a l t e r m s .

s t ro n g l y b o n d e d t o s u l f o n ic a c i d g r o u p s . O n e T h e a b i li ty o f i o n e x c h a n g e r e s in s t o w o r k

w a t e r m o l e c u l e a t t a c h e s i ts e l f t o f o u r s u l- i n b o t h a q u e o u s a n d n o n - a q u e o u s s y s te m s

f o n i c a c i d g r o u p s le a d i n g t o a r e d u c t i o n i n c o n f e r s u n i q u e a d v a n t a g e s . H y d r o p h o b i c sy s-

t h e n u m b e r o f a v a i la b l e a c i d g r o u p s w h i c h i n t e m s c a n b e c a ta l y z e d b y d r y m a c r o r e t i c u l a r

t u r n d e c r e a s e s t h e r a t e o f t h e r e a c t i o n . E x - r e si n s. T h e d r y i n g o f t h e r e s in s is m u c h e a s -

a m p l e s o f t y p e B 2 r e a c t i o n s a r e t h e d e h y d r a - i e r t h a n t h a t o f p - T S A . R e s i n s e v e n h a v i n g

t i o n o f a n a l c o h o l, t h e e s t e r i f ic a t i o n o f a c i d t h e e q u i v a l e n t s t r e n g t h o f s t r o n g m i n e r a l a c i d

wi t h a l c o h o l , e tc . H e r e a s t h e r e a c t io n p r o - c a n b e h a n d l e d w i t h o u t d a n g e r t o p e r s o n n e l.

c e e d s , t r a n s i ti o n f r o m B 2 t o A 1 t a k e s p l a c e D u e t o i ts h e t e r o g e n e o u s n a t u r e t h e r e s in ,

wi t h r e s u l t i n g d r o p i n t h e c a t a l y t i c a c ti v it y , t h o u g h i t c o n t a i n s a c i d a t h i g h c o n c e n t r a t i o n ,

T h e r e f o r e to m a i n t a i n t h e B - t y p e c h a r a c t e r , c a n b e u s e d c o n v e n i e n t l y i n m i l d s t e e l e q u i p -

i . e . , t o m a i n t a i n h ig h c a t a ly t i c a c ti v it y, w a t e r m e n t : t h e n u m b e r o f a c i d g r o u p s a t t h e s u r -

n e e d s to b e r e m o v e d f r o m t h e s y s t em a s s o o n f a c e o f t h e b e a d i n c o n t a c t w i t h e q u i p m e n t is

a s i t is g e n e r a t e d , a v e r y s m a l l p e r c e n t a g e o f t h e t o t a l n u m b e r

o f a c i d g r o u p s p r e s e n t , t h u s o b v i a t i n g t h e

p r o b l e m o f c o r r o s i o n . A g i t a t i o n c a n f u r t h e r

6 . A d v a n t a g e s a n d l i m i t a ti o n s o f i o n e x

r e d u c e a n y c o r r o s i o n b y m i n i m i z i n g t h e c o n -

c h a n g e

r e s i n s a s c a t a l y s t

t a c t b e t w e e n t h e r e s i n p a r t i c l e s a n d t h e

e q u i p m e n t .

T h e p a r t ic u l a t e n a t u r e o f t h e i o n e x c h a n g e T h e m a j o r d i s a d v an t a g e o f i o n e x c h a n g e

r e s i n s p e r m i t s m e c h a n i c a l s e p a r a t i o n o f t h e r e s i n s i n c a t a l y s is i s t h e i r r e l a t i v e l y l o w t h e r -

c a t a ly s t a n d t h e r e a c t a n t - p r o d u c t m i x t u r e b y m a l st a bi li ty . I o n e x c h a n g e r e s in s c a n w i t h -

f i lt r a ti o n o r d e c a n t a t i o n , t h u s e l i m i n a t i n g s t a n d t e m p e r a t u r e s b e l o w 1 25 C f o r l o n g p e -

d i s ti l la t i o n o r e x t r a c t i o n p r o c e d u r e s f o r r io d s . F o r m a c r o r e t i c u l a r r e s in s , o p e r a t i o n a t

p r o d u c t i s o la t io n . R e s i n s c a n b e u s e d a s c a ta - 1 5 0 C f o r a lo n g t i m e m a y c a u s e d e s u l f o n a -

l ys t i n c o n t i n u o u s p r o c e s s e s i n f i x ed b e d r e - t i o n l e a d i n g t o a r e l e a s e o f s u l f o n i c a c i d a s

a c t o r s . I n t h i s c a s e , s i z e o f t h e i o n e x c h a n g e we l l a s a d r o p i n t h e a c t iv i ty . I t is r e c o m -

r e s i n m a y n e c e s s i t a t e t h e u s e o f s p e c i al s u p - m e n d e d t h a t s u c h c a t a l ys t s a r e n o t u s e d

p o r t t r a y s [ 40 ]. P a r t i c l e s s h o u l d p r e f e r a b l y b e a b o v e 1 20 C . R e s e a r c h i s g o i n g o n t o d e -

o f u n i f o r m s iz e . O t h e r w i s e , s m a l l e r p a r t i c le s v e l o p i o n e x c h a n g e r e s i n s h a v i n g h i g h e r t h e r -

m a y f il l u p t h e s p a c e b e t w e e n l a r g e r p a r t i c l e s m a l s t a b il i ty , a n d t h i s w i l l b e d i s c u s s e d l a t e r

c a u s i n g i m p r o p e r d is t r ib u t i o n o f t h e re a c - i n t h e t e xt . N a t i o n c a n w i t h s t a n d t e m p e r a -

t a n t s i n t h e r e s i n b e d [4 1] . t u r e u p t o 2 0 0 C , b u t u n f o r t u n a t e l y s u c h

C a t a ly s i s b y i o n e x c h a n g e r e s i n s l o w e r s m a t e r i a l s a r e e x p e n si v e ; t h e u s e o f s u p p o r t e d


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p e r f l u o r i n a t e d s u l f o n ic a c i d m a y h o w e v e r r e - w i t h p - T S A , A m b e r l y s t- 1 5 a n d N a f i o n - H as

d u c e o v e r a l l o p e r a t i n g c o s t s, t h e c a t a ly s t , r e s p e c t i v e l y [ 42 ]. E t h e r i f i c a t i o n

o f p h e n o l w i t h i s o a m y l e n e w a s t r i e d a t l o w

t e m p e r a t u r e w i t h p - T S A a s t h e c a t a l y s t [ 7 ] .

7 . e lec t iv i ty o f ion exchange res in ca ta lys ts O n l y C - a l k yl a te d p r o d u c t w a s f o r m e d . H o w -

e v e r , e t h e r i f i c a t i o n p r o c e e d e d w e l l a t t h e

T h e se l e ct iv i ty o f i o n e x c h a n g e r c a t al y st s s a m e t e m p e r a t u r e w i t h A m b e r l y st - 1 5 a s t h e

o f t e n l e a d s t o y i e l d s w h i c h a r e c o n s i d e r a b l y c a t a ly s t .

h i g h e r t h a n t h o s e o b t a i n e d w i t h c a ta l y si s b y I n t h e a l k y l a ti o n o f p h e n o l w i t h o l e fi n s ,

d i s so l v e d e l e c t r o l y te s [1 6]. T h e i o n e x c h a n g e r s o m e r e m a r k a b l e d i f f e r e n c e s w e r e o b s e r v e d

d i s ti n g u i s h e s m o r e s h a r p l y b e t w e e n t h e v a r i- w i t h i o n e x c h a n g e r e s i n a s t h e c a t a ly s t i n t h e

o u s r e a c t a n t m o l e c u l e s . I o n e x c h a n g e r s a s

o - / p - p r o d u c t

d i s t r ib u t i o n [ 7 4 ]. W i t h a - m e t h -

c a t al y s ts a r e p e r h a p s a b o u t h a l fw a y b e t w e e n y l s t y re n e ( A M S ) a s t h e a l k y la t in g a g e n t , t h e

t h e n o n - s e l e c t i v e d i s s o l v e d e l e c t r o l y t e s a n d o - / p - d i s t r i b u t i o n w a s 1 6 : 8 4 a n d 3 : 9 7 w i t h

t h e e x t r e m e l y s e l e c ti v e e n z y m e s . I o n e x- p - T S A a n d A m b e r l y st - 1 5 a s t h e c a t al y st , r e -

c h a n g e r e s in s c a n b e t a i l o r - m a d e t o u s e a s a s p e ct iv e ly ; w i t h d i i s o b u t y l e n e ( D I B ) a s t h e

m e a n s f o r s e l e c t i v e c a t a l y si s o f s m a l l a l k y la t in g a g e n t , t h e v a l u e s w e r e 4 1 : 5 9 a n d

m o l e c u l e s i n t h e p r e s e n c e o f l a r g e m o l e c u l e s . 5 9 5 w i t h p - T S A a n d A m b e r l y st - 1 5 a s t h e

A c r o s s l i n k d e n s i t y m a y b e c h o s e n t o i n h i b i t c a t a ly s t , r e s p e c t i v e l y ; a n d w i t h 1 - o c t e n e a s

ma t r i x e x p a n s i o n s u f f i c i e n tl y s o t h a t l a r g e t h e a l k y l a t i n g a g e n t , t h e r a t i o w a s 7 2 2 8 a n d

m o l e c u l e s a r e e x c l u d e d f r o m t h e i n t e r i o r o f 5 9 : 4 1 w i t h p - T S A a n d A m b e r l y st - 1 5 a s t h e

t h e b e a d b y s i e v e a c t i o n w h i l e s m a l l c a ta l y st , r e s p ec t iv e l y . R e c e n t l y , C h a n d r a a n d

m o l e c u l e s m a y e n t e r t h e m a t r i x t h u s f a v o u r- S h a r m a [ 4 4 ] h a v e o b s e r v e d t h a t m e t h y l

t e r t -

i n g t h e r e a c t i o n o f t h e s m a l l m o l e c u l e s o n l y b u t y l e t h e r ( M T B E ) c a n b e a d v a n t a g e o u s l y

[2 5]. O t h e r s p e c if i c e x a m p l e s o f s e l e ct i v e r e s i n u s e d f o r t h e b u t y l a t i o n o f p h e n o l w i t h A m -

c a t a ly s i s , w h i c h c a n n o t b e e x p l a i n e d s imp l y b e r l ys t - 15 a s c a t a ly s t . T h e s e le c t i v it y f o r 2 -

i n t e r m s o f m o l e c u l a r s i z e a n d s i e v e a c t i o n , t e r t - b u t y l p h e n o l c a n b e i m p r o v e d b y c ar e f u l ly

i n c l u d e c o n d e n s a t i o n o f f u r f u r a l w i t h a n s e l e c t in g t h e t e m p e r a t u r e a n d t h e l e ve l o f

a l d e h y d e . S u c h e f f e c t s m a y b e t e n t a t i v e ly c o n v e r s i o n . F o r t h e a l k y l at i o n o f s u b s t i t u t e d

e x p l a i n e d b y d i f f e r e n c e s i n s o r p t io n o f v a r i- h y d r o q u i n o n e s s u c h a s m e t h y l h y d r o q u i n o n e ,

o u s r e a c ta n t s . T h e p r e f e r e n t ia l s o r p ti o n o f p h e n y l h y d r o q u i n o n e a n d

t e r t - b u t y l h y d r o -

o n e o f t h e r e a c t a n t s i n t h e r e s i n m a y f a v o u r q u i n o n e , K i m e t a l . [ 1 7 7 ] h a v e r e p o r t e d b e t -

a r e a c t i o n w h i c h i s i n s i g n i f i c a n t i n c a t a ly s i s t e r s e l e c ti v i ty t o 2 , 5 - d i - t e r t - b u t y l h y d r o q u i -

b y d i s so l v e d e l e c tr o l y te s . I n t h e a b o v e - m e n - n o n e s w i t h A m b e r ly s t -1 5 c at a ly s t t h a n 7 0

t i o n e d c a s e , d i s s o l v e d b a s e s u n d e r o t h e r w i s e s u l p h u r i c a c i d . T h e s e l e c ti v i t y o f 2 ,5 - s ub -

i d e n t i c a l c o n d i t i o n s a lm o s t e x cl u si v el y g i ve s t i t u te d h y d r o q u i n o n e s w a s i n t h e d e s c e n d -

s e l f - c o n d e n s a t i o n o f t h e a l d e h y d e , i n g o r d e r o f

t e r t - b u t y l ,

p h e n y l , a n d m e t h y l h y -

I o n e x c h a n g e r e s in s s h o w e d h i g h e r s e l ec - d r o q u i n o n e s .

t iv i ty f o r t h e d e s i r e d p r o d u c t i n m a n y r e a c - I n t h e a c i d - c a ta l y z e d c r a c k i n g o f M T B E ,

t io n s . I n th e a l k y l a t i o n o f b e n z e n e w i t h c o n s i d e r a b l e i m p r o v e m e n t i n t h e s e le c t iv i ty

s t y r e n e , t h e p e r c e n t a g e y i e ld o f a l lo y la te d f o r t h e d e s i r e d p r o d u c t c o u l d b e r e a l i z e d b y

p r o d u c t w a s 0 , 1 0.7 a n d 1 3.7 w i t h p - T S A , u s i n g a s u r f a c e - s u l p h o n a t e d p o r o u s p o l y s ty -

A m b e r l y st - 1 5 a n d N a f i o n - H a s t h e c a ta l y st , r e n e c a t a ly s t i n s t e a d o f t h e c o m m e r c i a l l y

r e s p e c t i v e l y [4 2] . I n t h e a ll o y la t io n o f t o l u e n e a v a i l a b l e re s i n s . T h i s m a y b e a t t r i b u t e d t o

w i t h s t y r e n e , t h e p e r c e n t a g e y i e l d o f t h e t h e f o r m a t i o n o f b y - p r o d u c t s i n t h e s o l id

a l k y l a t e d p r o d u c t w a s 5 1 .5 , 6 1.5 a n d 8 6. 2 m a t r i x r e g i o n s o f t h e c o m m e r c i a l c a t a l y s ts


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8 A. Chakrabart i, M.M . Sharm a/React . Polym. 20 1993) 1-45

w h i c h is i n h i b i t e d b y p r o v i d i n g t h e - S O 3 H o b v i o us l y b e r a t e - c o n t r o l l in g s i n ce i n t h is l im -

g r o u p s o n l y o n t h e s u r f a c e o f t h e c a t a ly s t i ti n g c a s e a ll r e a c t a n t m o l e c u l e s r e a c t a s

[4 5] . s o o n a s t h e y r e a c h t h e s u r f a c e o f t h e c a t a l y s t

p a r t i c l e . I f t h e c h e m i c a l r e a c t i o n i s m u c h

s l o w e r t h a n t h e d i f f u s i o n p r o c e s s e s , s o r p t i o n

8. i n e t i cs o f io n e x c h a n g e r e s i n c a t a l y s i s e q u i l i b r i u m o f t h e r e a c t a n t s i s e s t a b l i s h e d

a n d u p h e l d t h r o u g h o u t t h e c a t a l y s t p a r t i c l e

8 .1 . R o l e o f m a s s t r a n s fe r

s i n c e d i f f u s i o n i s e n o u g h t o m a k e u p f o r t h e

d i s a p p e a r a n c e o f r e a c t a n ts b y c h e m i c a l r ea c -

T h e t h e o r y o f c a t al y s is b y i o n e x c h a n g e r s t io n . T h e o v e r a l l r a t e is t h u s c o n t r o l l e d b y

h a s n o t y e t b e e n w e l l - e s ta b l i s h e d . I n a ll c a s e s t h e r a t e o f t h e c h e m i c a l r e a c t i o n t h r o u g h o u t

w h i c h h a v e s o f a r b e e n s t u d i e d a n d i n w h i c h t h e p a r t ic l e . I f i n t r a p a r t i c l e d i f fu s i o n is m u c h

l i m i t a ti o n s d u e t o s l ow d i f fu s i o n p r o c e s s c a n s l o w e r t h a n th e a c t u a l c h e m i c a l r e a c t i o n , t h e

b e r u l e d o u t , t h e k i n e t i c o r d e r o f t h e c h e m i - r e a c t a n t m o l e c u l e s w i ll r e a c t b e f o r e t h e y h a v e

c a l r e a c t i o n i n t h e p a r t i c le s w a s f o u n d t o b e t i m e t o p e n e t r a t e i n t o t h e i n t e r i o r o f t h e

t h e s a m e a s i n h o m o g e n e o u s c a t a l y si s b y a c a t a l y s t p a r t i c l e . I n t h i s l a t t e r l i mi t i n g c a s e ,

d i s s o l v e d e l e c t r o l y t e . T h i s is s t r o n g e v i d e n c e t h e r e a c t i o n o c c u r s o n l y i n a t h i n l a y e r a t t h e

i n s u p p o r t o f th e v i e w t h a t t h e r e a c t i o n s u r f a c e a n d i ts r a t e is c o n t r o l l e d b y e i t h e r

m e c h a n i s m i s e s s e n t ia l l y t h e s a m e in b o t h f il m d i f fu s i o n o r c h e m i c a l r e a c t i o n a t t h e

c a s e s . H o w e v e r , t h e r e a r e d i f f e r e n c e s i n r e - s u r f a c e . If t h e f i lm d i ff u s i o n i s s u f f i c i e n t ly

a c t i o n r a t e s, e v e n w h e n t h e a m o u n t o f c a t a - f as t, t h e p r o c e s s is c o n t r o l l e d b y c h e m i c a l

l ys t i n c o u n t e r - i o n e q u i v a l e n t s ) i s t h e s a m e r e a c t i o n a t t h e s u rf a c e . I n t r a p a r t i c l e d if f u-

i n b o t h c a s e s . A s i g n i f i c a n t d i f f e r e n c e b e - s i o n c a n a f f e c t t h e o v e r a l l r a t e o f r e a c t i o n ,

t w e e n h o m o g e n e o u s c at al ys is a n d h e t e r o g e - b u t i t c a n n e v e r b e t h e s o le r a t e - d e t e r m i n i n g

n i z e d h o m o g e n e o u s c a t al y si s is t h e p r e s e n c e s t e p a s d i f f u s io n a n d c h e m i c a l r e a c t i o n

o f d i f f u si o n a l p r o c e s s e s i n t h e l a t e r c a s e. a r e p a r a l l e l s t ep s , o c c u r r i n g s i m u l t a n e o u s l y

M o s t o f t h e i o n e x c h a n g e r e s i n c a t a l y z e d w i t h i n t h e r e s i n b e a d .

r e a c t i o n s r e p o r t e d i n t h e l i t e r a t u r e h a v e b e e n T h e s e c o n s i d e r a t i o n s s u g g e s t t h a t , i n t h e

c a r r i e d o u t i n t h e li q u i d p h a s e ; t h e r e f o r e , l i m i t in g c a s es , t h e o v e ra l l r a t e o f a n y i o n

o u r d i s c u s si o n w i l l b e l i m i t e d t o t h e l iq u i d - e x c h a n g e r e s i n c a t a l y z e d r e a c t i o n i s co n -

p h a s e r e a c t io n s . H o w e v e r , t h e s a m e t r e a t - t r o l l e d b y : i ) f i lm d i ff u s io n ; i i ) c h e m i c a l

m e n t c a n b e a d a p t e d , w i t h a f e w o b v i o u s r e a c t i o n t h r o u g h o u t t h e p a r t ic l e ; a n d

i i i )

c h a n g e s , t o g a s - p h a s e r e a c t io n s . I n o r d e r f o r c h e m i c a l r e a c t i o n a t t h e s u r fa c e . O b v i o u s l y

t h e r e a c t i o n t o o c c u r , r e a c t a n t m o l e c u l e s i n t e r m e d i a t e c a s e s a r i s e i f t h e r a t e s o f i n d i-

m u s t f ir s t m i g r a t e f r o m t h e b u l k s o l u t io n i n t o v i d u a l st e p s a r e c o m p a r a b l e . H o w e v e r , i t i s

t h e i o n e x c h a n g e r ; a n d m u s t r e a c t ; t h e r e a c - f o u n d g e n e r a l l y t h a t fi lm d i f fu s i o n d o e s n o t

t i o n p r o d u c t s m u s t t h e n m i g r a t e b a c k i n t o c o n t r o l t h e o v e r a l l r a t e i n i o n e x c h a n g e r e s i n

t h e s o lu t i o n . T h u s , t h r e e p h e n o m e n a c a n c a t a l y z e d p r o c e s s e s. I f t h e v i sc o s it y o f t h e

a f f ec t t h e r a t e o f o v e r a l l p r o c e ss : i ) d i ff u - r e a c t a n t m i x t u r e i s t o o h i g h o r t h e s p e e d o f

s i o n o f t h e r e a c t a n t s a n d p r o d u c t s a cr o s s t h e a g i t a t io n i s t o o lo w , t h e n f il m d i f fu s i o n m a y

f i lm N e r n s t d i f f u s i o n l a y e r ) s u r r o u n d i n g t h e c o n t r o l [ 16 ]. B u t t h e s e a r e e x c e p t i o n a l c a s e s .

ca ta lys t pa r t i c le ;

i i )

d i f fu s i o n o f t h e r e a c - O f t e n t h e o v e r a ll r a t e is c o n t r o l l e d b y a

t a n t s a n d p r o d u c t s i n t h e i n t e r i o r o f t h e c o m b i n a t i o n o f i n t r a p a r t i c l e r e a c t i o n a n d i n -

c a t a l y s t p a r t i c l e ; a n d

i i i )

c h e m i c a l r e a c t i o n t r a p a r t i c le d i f fu s i on .

a t t h e a c t iv e s it e s. I f f il m d i f fu s i o n i s m u c h T h e p r o c e d u r e f o r d i s c e r n i n g t h e c o n t r o l -

s l o w e r t h a n th e c h e m i c a l r e a c t i o n , i t m u s t l in g m e c h a n i s m in i o n e x c h a n g e re s i n c a t -


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A. Chakrabarti , M .M. Sharma / React . Polym. 20 (1993) 1-4 5 9

a l y z e d l i q u i d / s o l i d r e a c t i o n h a s b e e n d i s - a c c e s si b il it y = f ( d i v i n y l b e n z e n e c o n t e n t , p a r -

c u s s e d i n d e t a i l b y D o r a i s w a m y a n d S h a r m a t ic l e s iz e , p o r o si t y, r e a c t i o n m e d i u m , d i ff u -

[46 ]. T h ey h av e a l so d i scu sse d th e p ro ced u re s s iv ity) .

f o r d i s c e r n i n g t h e c o n t r o l l i n g m e c h a n i s m i n F o r a g i v e n t y p e o f a c i d r e s i n c a ta l ys t ,

g a s / l i q u i d / s o l i d ( w h e r e t h e so l id a c ts as t h e h i g h e r d i v i n yl b e n z e n e c o n t e n t w i ll r e d u c e t h e

ca ta ly s t) r eac t io n s ca r r i ed o u t in s lu r ry o r sw e l l in g ab i l it y o f th e r e s in , t h u s r ed u c in g

f ix ed b ed re ac to r s [4 7 ] . C ar ra [4 8 ] h as d is - access ib il i ty to th e cata ly s t . In th e p re sen ce

c u s s e d t h e t y p e o f r e a c to r s u s e d , r o le o f o f m o r e p o l a r r e a c t i o n m e d i u m , t h e

h y d r o d y n a m i c f a ct o rs , m a s s t r a n sf e r i n a gi - p o l y m e r - b o u n d - S O 3 H g r o u p s a r e m o r e d is -

t a t e d s y st e m s , r o l e o f i n t r a p a r t i c l e d i f fu s i on , s o c i a t e d l e a d i n g t o a d e c r e a s e i n t h e a c id i ty

etc . ,

f o r i o n e x c h a n g e r e s i n c a t a l y z e d r e a c - o f t h e s u l fo n i c a c i d r e s in . W i t h m o r e p o l a r

t io n s , c o m p o n e n t s , t h e s w e l li n g o f t h e r e s i n i s

h ig h er an d , h en c e , t h e access ib i li t y i s im-

8 . 2 . K i n e t i c m o d e l

p ro v ed . B u t t e r sack [4 9 ] h as fu r th e r c l a ss i f i ed

t h e a c c e s si b il it y i n t o n o n - i n t e r a c t i o n a n d i n -

T h e sco p e o f ca t a ly t ic ap p l i ca t io n o f t e rac t io n access ib i li t y. T h e fo rm er i s ak in to

s t r on g l y a c i d ic i o n e x c h a n g e r e s i n s i n t h e t h e t e r m d i s p e r s i o n u s e d i n t h e c o n v e n -

l i q u id p h a s e e x t e n d s f r o m e s s e n t i a ll y h o m o - t i o n a l h e t e r o g e n e o u s c a ta l ys is fo r d e f i n i n g

g e n e o u s m e c h a n i s m s t o c l as s ic a l h e t e r o g e - t h e f r a c t io n o f c a t al y ti c a ll y a c t iv e g r o u p s a t

n e o u s c a t al ys is . D e p e n d i n g o n t h e i n t e r a c - t h e s u r f ac e a n d is r e l a t e d t o t h e m o r p h o l o g y

t i o n o f t h e s o lv e n t w i t h t h e a c i d g r o u p s a n d o f t h e r e s i n i n t h e d r y s t at e . T h e l a t t e r r e -

t h e p o l y m e r b a c k b o n e , d i f f e r e n t d e g r e e s a n d f l ec t s t h e i n f l u e n c e o f t h e s o l v e n t a n d a d -

p o s s ib l y t y p e s o f s w e l l in g o c c u r. T h e i d e a l - s o r b e d m o l e c u l e s ( t h e s t e a d y s t a t e r e a c t i o n

i z e d h o m o g e n e o u s s t a te r e q u i re s c o m p l e t e m e d i u m ) o n t h e i o n e x c h a n g e r e s in c a ta ly st .

sw e l l in g an d to t a l d i s so c ia t io n o f th e po ly - T h e access ib i li t y i s a l so a fu n c t io n o f th e

m e t - b o u n d - S O 3 H g r o u p ( s p e c if i c c a ta ly s is ), e f f e c t iv e d i ff u si v it y o f t h e r e a c t a n t s w i t h i n

W h e r e a s , t h e h e t e r o g e n e o u s s t a t e i s c h a r a c - t h e p o r e s , w h i c h is r e l a t e d t o t h e T h i e l e

t e r i z e d b y a d i r e c t i n t e r a c t i o n o f t h e s u b - m o d u l u s t h r o u g h t h e e q u a t i o n

s t ra t e w i th t h e p o ly m e r - b o u n d - S O 3 H g r o u p

= R f k / D

(g en era l ca t a ly s i s) . Mo s t r e s in -ca ta ly ze d reac -

t io n s can b e c la ss i f i ed e i th e r a s q u as i -h o m o - w h e re R is th e r ad iu s o f th e ca ta ly s t p a r t i c l e ,

g e n e o u s

( e . g . ,

h y d ro ly s i s o f su c ro se , ca r - k i s t h e r eac t io n r a t e co n s tan t , an d D i s th e

b o x y l i c e s t e r s ) o r q u a s i - h e t e r o g e n e o u s

( e . g . ,

e f fec t iv e d i f fu s iv ity o f th e r eac ta n t .

b e n z e n e p r o p y l a t io n , i s o b u t y l e n e o l i g o m e r - A p a r t f r o m t h e a d s o r p t i o n i s o t h e r m a n d

i z a ti o n ). C o m p l i c a t e d s i t u a ti o n s a r i se w h e r e d i s t r ib u t i o n c o e f f i c i e n t o f t h e re a c t a n t , t h e

t h e s o l v e n t c a u s e s o n l y p a r t i a l d i s s o c i a ti o n o f T h i e l e m o d u l u s a l so a ff e c ts t h e a c t u a l n u m -

- S O 3 H g r o u p s , d u e t o a l o w d e g r e e o f s o lv a - b e r o f s i te s , o u t o f t h e t o t a l a c c e s s ib l e s it e s,

t i o n

( e . g . ,

M T B E sy n th es i s ) [49 ]. o ccu p ied b y th e r eac tan t . T h e e f fec t o f in t r a -

T h e r a t e o f a r e s i n - c a t a ly z e d r e a c t i o n w i ll p a r t i c le d i f fu s i o n c a n b e i n c o r p o r a t e d in t h e

b e a fu n c t io n o f (1 ) th e ac id ity an d (2 ) th e r a t e ex p re ss io n b y w ay o f th e e f fec t iv en e ss

access ib i li t y o f th e ac t iv e s i t e s [1 3 ] ,

i . e . ,

f a c t o r ~ w h i c h c a n b e c o r r e l a t e d t o t h e

r = f ( ac id i ty , access ib il i ty ) T h ie l e mo d u lu s . A tw o -p h ase m o d e l h as b e en

w h e r e s u g g e s t e d f o r t h e e f f e c t i v e n e s s f a c t o r o f a

ac id i ty = f ( ty p e an d n u m b e r o f ac id g ro u p s , ma cro re t i cu la r r e s in [5 0 ] , s in ce i t i s e s sen t i a l

d i v i n y lb e n z e n e c o n t e n t , r e a c t io n m e d i u m ) t o t a k e a c c o u n t o f b o t h m a c r o p o r e a n d m i -

an d c ro -p h ase d i f fu s io n .


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I n t h e a b s e n c e o f a n y i n t r a p a r t i c l e d if f u - s a t i s fa c t o r i ly a p p l i e d in t h e c a s e o f i s o b u t y l-

s i on l i m i t at i o n , t h e r a t e o f r e a c t i o n c a n b e e n e o l i g o m e r i z a t i o n [ 55 ], d i m e r i z a t i o n o f

e x p r es s e d u s in g a s i m p le p s e u d o h o m o g e - i s o a m y l e n e [ 5 6 ] , a n d b e n z e n e p r o p y l a ti o n

n e o u s m o d e l o r a m o r e c o m p l e x m o d e l b a s e d [3 4]. A m o r e c o m p l e x s i t u a t io n a ri s e s f o r t h e

o n t h e L a n g m u i r - H i n s h e l w o o d m e c h a n i s m , e t h e r if i c a ti o n r e a c ti o n s o f o l ef in s w i t h a lc o -

T h e p s e u d o h o m o g e n e o u s m o d e l is b a s e d o n h o ls M T B E / E T B E / T A M E s yn th es is ): d e -

t h e H e l f f er i c h a p p r o a c h w h i c h t r e a t s t h e p e n d i n g u p o n t h e c o n c e n t r a t i o n o f t h e a lc o -

c a ta l ys i s b y i o n e x c h a n g e r es i n s a s h o m o g e - h o l , t h e r e c an b e a t r a n s i t io n f r o m g e n e r a l t o

n e o u s c a t a l y si s c o n f i n e d w i t h i n t h e i n t e r n a l s p e c i f i c c a t al y s is . F o r M T B E s y n t h e s i s , a t

c a t a l y s t ma s s

i . e . ,

r e s i n v o l u m e ) , w h e r e i n l o w e r c o n c e n t r a t i o n o f m e t h a n o l t h e c a ta l y si s

t h e r e a c t a n t s , p r o d u c t s a n d s o l ve n t s a r e i n i s b y t h e p o l y m e r - b o u n d - S O 3 H g r o u p s

d i s t r ib u t i o n e q u i l i b r i u m w i t h t h e b u l k s o lu - w h i c h a r e v e r y a c t iv e b u t i f t h e c o n c e n t r a t i o n

t io n . H e r e , t h e r e a c t i o n m e c h a n i s m is s i m i l ar o f m e t h a n o l i s i n c r e a s e d , m e t h a n o l d i ss o c i-

t o t h e o n e o b s e r v e d w i t h t h e d i s so l v e d e l e c - a t e s t h e a c i d g r o u p s a n d s o l v a te d p r o t o n s

t ro l y te s . T h e d i ff e r e n c e i n t h e p e r f o r m a n c e b e c o m e t h e c a t a ly t ic a g e n t s w h i c h a r e r e l a -

o f t h e tw o is a t t r i b u t e d t o t h e s e l e c t iv e s o r p - t iv e l y l e s s a c t iv e . A t v e r y h i g h m e t h a n o l c o n -

t i o n o f o n e o f t h e r e a c t a n t s b y t h e r e s in c e n t r a t i o n s , t h e m e t h a n o l is n o l o n g e r a b l e

d e p e n d i n g u p o n t h e n a t u r e e . g . , p o l a r i t y ) o f t o a f f e c t t h e r a t e e i t h e r a s r e a c t a n t o r a s

t h e r e a c t a n t s / s o l v e n t m e d i u m . I n t h is m o d e l , s o l ve n t , h a v i n g c o m p l e t e l y l e v e l le d t h e c a t a -

l i n e a r r e l a t io n s h i p s a r e a s s u m e d b e t w e e n t h e l ys t a c ti vi ty . S o m e r e s e a r c h e r s V o l o c h et a l .

r e a c t a n t c o n c e n t r a t i o n a t t h e a c t iv e s it e s [5 7], S u b r a m a n i a m a n d B h a t i a [5 8]) h a v e u s e d

w i t h in t h e r e s in a n d t h a t i n t h e b u lk . B u t t e r- a p s e u d o h o m o g e n e o u s m o d e l i n t h e c as e o f

s a c k [4 9] h a s d e f i n e d a c a t a ly t i c e f f ic i e n c y q ) M T B E s y n t h e s is a n d h a v e b e e n a b l e to co r -

a s t h e r at i o o f t h e o v e ra l l r e a c t i o n r a t e p e r r e l a t e t h e e x p e r i m e n t a l k i n e t i c d a t a s a ti sf a c-

a c i d s it e, o b t a i n e d w i t h a r e s i n c a t a ly s t t o t o ri ly ; n o n e t h e l e s s L a n g m u i r - H i n s h e l w o o d

t h a t o b t a i n e d w i t h a m i n e r a l a c id . T h e q o r R i d e a l - E l e y m o d e l s h av e b e e n m o r e

v a lu e s f o r m a n y r e a c ti o n s h a v e b e e n f o u n d t o w i d e l y u s e d H o f f m a n n

e t a l .

[ 5 9 - 6 2 ] , A n c i l -

b e i d e n t i c a l t o t h e d i s t r i b u t i o n c o e f f i c i e n t s , l o t ti e t a l . [ 5 ] , G i c q u e l a n d T o r c k [ 6 3] , G a t e s

T h e p s e u d o h o m o g e n e o u s a p p r o a c h is p a r t ic - a n d J o h n s o n [ 64 ], C u n i l l e t a l . [65]), and

u l a r l y a p p l i c a b l e i n c a s e s w h e r e o n e o f t h e t h e s e c a n b e a p p l i e d a n d e x t r a p o l a t e d o v e r a

r e a c t a n t s o r s o l v e n t is h i g h ly p o l a r . I n t h e w i d e r r a n g e o f c o n c e n t r a t i o n s . W h e n t h e

p r e s e n c e o f p o l a r c o m p o n e n t s , s o l v a ti o n o f r a t e - li m i t i n g s t e p i n vo l ve s a r e a c t a n t f r o m a

t h e p o l y m e r - b o u n d - S O 3 H g r o u p t a k e s f lu i d p h a s e w i t h o n e t h a t is a d s o r b e d , t h e

p l a c e , a n d th e c a ta l ys i s is b y t h e s o l v a te d m e c h a n i s m is c a l l e d a R i d e a l - E l e y m e c h a -

p r o t o n . F o r e x a m p l e , t h is m o d e l h a s b e e n n i sm . If a ll t h e r e a c t a n t s in v o l v e d i n t h e

s u c c es s fu l ly u s e d f o r t h e h y d r o l y si s o f s u - r a t e - d e t e r m i n i n g s t e p a r e a d s o r b e d , t h e c o r -

c r o s e [5 1], t h e h y d r o ly s is o f c a r b o xy l ic e s t e r s r e s p o n d i n g k i n e t i c b e h a v i o u r i s t e r m e d

[5 1], t h e h y d r a t i o n o f o l e f in s [5 2,5 3], a n d t h e L a n g m u i r - H i n s h e l w o o d . A fe w r e a c t i o n s e x -

d e h y d r a t i o n o f a l c o h o l s [5 4] . h i b i t m a x i m u m o f r e a c t i v i t y a t c e r t a i n s u b -

W h e r e , d u e t o t h e n o n - p o l a r n a t u r e o f t h e s t ra t e c o n c e n t r a t i o n e . g . , v a p o u r - p h a s e d e -

r e a c t a n t o r s o l ve n t, t h e p o l y m e r - b o u n d h y d r a t i o n o f a l c o h o l s , v a p o u r - p h a s e s y n t h e s i s

u n d i s s o c ia t e d - S O 3 H g r o u p is t h e p r o t o n o f M T B E / E T B E [6 6]). S u c h a m a x i m u m c a n

d o n o r , a s i m p l e h o m o g e n e o u s m o d e l m a y b e e x p l a in e d b y a L a n g m u i r - H i n s h e l w o o d

n o t f it t h e d a t a . A m o r e s u i t a b le a p p r o a c h i s m e c h a n i s m , b a s e d o n t w o - s it e a d s o r p t i o n o f

o n e b a s e d o n t h e L a n g m u i r - H i n s h e l w o o d o r i s o b u t e n e a n d th e e th e r , a n d a s i m p le a d -

R i d e a l - E l e y m e c h a n i s m . T h e s e h a v e b e e n s o r p ti o n o f m e t h a n o l . B u t t e r s a ck [ 4 9 ] h a s


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11

s u g g e s t e d a m o r e g e n e r a l c o n c e p t o f v a r ia b l e

8 .3 . D i s t r ibu t ion coe f f i c i en t

a c t i v e c e n t r e s , i n w h i c h , a t l o w d e g r e e o f

a d s o r p t i o n , e a c h s u b s t r a t e m o l e c u l e r e q u i r e s A s d i s c u s s e d e a r li e r , w h e n c a ta l ys i s b y t h e

a c e r t a i n n u m b e r o f a c i d s it e s t o f o r m a n c a t i o n e x c h a n g e r i s s i m i l a r t o h o m o g e n e o u s

a c t i v e c e n t r e . A s i s k n o w n f o r a u s u a l L a n g - c a t al y s is , t h e a c t u a l c o n c e n t r a t i o n o f t h e d i f-

m u i r i s o t h e r m , a f r a c t i o n o f s i te s p a r t i c i p a t e f e r e n t c o m p o n e n t s o f t h e r e a c t i o n m i x t u r e i n

i n t h e a d s o r p t i o n a n d a n o t h e r f r a c t i o n o f t h e r e s i n p h a s e m a y n o t b e t h e s a m e a s t h a t

s i te s r e m a i n u n o c c u p i e d . W h e n al l s i te s p a r - i n t h e b u l k s o l u t io n , s i n c e t h e m i c r o e n v i r o n -

t i c ip a t e i n t h e a d s o r p t i o n , t h e m a x i m u m r e - m e n t o f t h e r e s i n m a y d i f f e r s u b s t a n ti a l ly

a c t i o n r a t e is a c h i e v e d . A f t e r a t t a i n m e n t o f f r o m t h e b u l k . T h e r e m a y b e p r e f e r e n t i a l

s a t u r a t i o n , f u r t h e r a d s o r p t i o n o f t h e s u b - d i s t r i b u t io n o f s o m e o f t h e c o m p o n e n t s d e -

s t r a t e m o l e c u l e s is p o s s ib l e b y l o w e r i n g t h e p e n d i n g o n t h e i r r e l at i v e c o m p a t i b i l it y w i t h

s iz e o f t h e a c ti v e c e n t r e s d o w n t o o n e a c i d t h e r e s i n p h a s e . T h e r e f o r e , k n o w l e d g e o f t h e

g r o u p p e r s u b s t r a t e m o l e c u l e . T h i s s i z e -r e - d i s t r i b u t i o n c o e f f i c i e n t s i s n e c e s s a r y t o f i n d

d u c t i o n o f t h e a c t iv e c e n t r e s c a u s e s a d e - o u t t h e a c t u a l c o n c e n t r a t i o n o f t h e d i f f e r e n t

c r e a s e o f t h e a c id i ty a n d t h e re a c t i o n r a te . c o m p o n e n t s i n t h e r e s i n p h a s e . D i s t r i b u t i o n

T h u s th e m a x i m u m o f r e ac t iv i ty d e p e n d s o n c o e ff i ci e n t o f a p a r t ic u l a r c o m p o n e n t is d e -

t h e p r o t o n a c c e p t o r a b il it y o f t h e s u b s t r a t e ; f i n e d a s t h e r a t io o f t h e c o n c e n t r a t i o n o f t h a t

t h e h i g h e r t h e a b il it y t h e s h a r p e r is t h e m a x i - c o m p o n e n t i n t h e r e s in p h a s e t o t h a t in t h e

m u m a n d t h e l o w e r i s t h e s u b s t r a t e c o n c e n - b u l k p h a s e . D i s t r i b u t i o n c o e ff i c i en t c a n b e

t r a t i o n a t m a x i m u m r e a c ti v it y . I n t h e e x - f o u n d o u t b y t h e m e t h o d d e s c r i b e d b y H e l f -

t r e m e c a s e w h e n t h e p r o t o n a c c e p t o r a b il it y f e r ic h [6 9,7 0]. T w o m e t h o d s h av e b e e n s u g -

o f t h e s u b s t r a t e i s v e r y l ow , th e m a x i m u m g e s t e d f o r t h is p u r p o s e . I n t h e f ir s t o n e , t h e

d i s a p p e a r s a t i n f in i t e s u b s t r a t e c o n c e n t r a - r e a c t a n t s a r e e q u i l i b r a t e d w i t h t h e c a ta l ys t

t i o n s , a n d t h e g e n e r a l k i n e t i c s r e d u c e s t o t h e f r o m w h i c h t h e c a ta l y t ic a l ly a c t iv e s p e c i e s i s

R i d e a l - E l e y k i n e t ic s . W h e n o p e r a t i n g i n a r e p l a c e d w i t h s o m e i n a c ti v e i o ns . I t m a y n o t

s o l v e n t w i t h h i g h e r p r o t o n a c c e p t o r ab i li ty p r e s e n t t h e a c t u a l p i c t u r e ; t h e r e p l a c e m e n t

t h a n t h a t o f t h e s u b s t r a t e , t h e a d d i t i o n a l o f c a t a ly t i c al l y a c t i v e s p e c i e s b y s o m e i n a c -

i n f l u e n c e o f t h e s u b s t r a t e c a n b e n e g l e c t e d , t iv e i o n s m u s t c h a n g e t h e e n v i r o n m e n t w i t h i n

a n d t h e s t a t u s o f t h e a c i d si t e s i s n e a r l y t h e r e s i n p h a s e , l e a d i n g t o a c h a n g e i n t h e

e x c lu s iv e ly d e t e r m i n e d b y s o l v at i on , s o t h a t d i s t r i b u t io n o f t h e c o m p o n e n t s . T h e o t h e r

a n a ct i ve c e n t r e s h o u l d b e i d e n t i c a l w i t h a m e t h o d , w h i c h i s m o r e a c c u ra t e , c o n s is t s o f

s i n g l e s o l v a t e d a c i d s i te . T h u s , t h e d e a c t i v a - e q u i l i b r a t i n g s m a l l p a r t i c l e s o f t h e c a t a l y s t

t i o n o f t h e r e s i n c a t al y s t b y t h e s u b s t r a t e h a s w i t h t h e r e a c t a n t s t o e n s u r e t h e a t t a i n m e n t

b e e n e x p l a i n e d s a t is f a ct o r il y b y t h e c o n c e p t o f s o r p t i o n e q u i l i b r i u m b e f o r e a n y a p p r e c i a -

o f v a r i a b le a c ti v e c e n t r e s f o r t h e p r o p y l a t i o n b l e c o n v e r s i o n o c c u r s . T h e n t h e c o n t e n t s o f

o f b e n z e n e B u t t e r s a ck

et al .

[6 7]). t h e r e s i n a r e e l u t e d b y s o m e s o l v e n t , a n d t h e

r e a c t i o n i s c o m p l e t e d i n t h e e l u a t e b y s o m e

s o l u b l e c a ta l ys t. T h e a m o u n t o f th e p r o d u c t s

R e a c t i o n s u n d e r s u p e r c r i t i c a l c o n d i t i o n s

i n t h e e l u a t e w h i c h i s s t o i c h i o m e t r i c a l l y

T h e m a n u f a c t u r e o f i s o p r o p a n o l b y h y d r a - e q u i v a l e n t t o t h e a m o u n t o f r e a c t a n t i n it ia l ly

t io n o f p r o p y l e n e a n d s e c - b u t a n o l b y h y d r a - t a k e n u p b y t h e r e s i n ) i s t h e n a n a l y t ic a l l y

t i o n o f b u t e n e s m a y i n vo l v e s u p e r c r it i c a l c o n - d e t e r m i n e d . I n t h is m e t h o d , t h e r e i s n o p ro -

d i t io n s . H e r e f ix e d b e d r e a c t o r s a r e e m - v i s io n f o r e s t i m a t i n g t h e d i s t r i b u t i o n c o e ff i-

p l o y e d . T h e r e is h a r d l y a n y l i t e r a t u r e o n t h e c i e n t o f t h e p r o d u c t w h i c h n e e d s t o b e c on -

k i n e t i c s i n s u c h r e a c t i o n s y s t e m s [6 8]. s i d e r e d i n t h e c a s e o f a r e v e r s i b l e r e a c t i o n .


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TABLE 1

Physical properties of some cation exchange resins

Catalyst Properties

Crosslinking density Surface rea Pore volume Ca paci ty Maximum perating

( DVB) (m2/g) (ml/g) (meq/g) temperature (C)

Amberlyst-15 20 45 0.35 4.8 120

Amberlyst-35 20 44 0.41 5.2 140

Amberlyst XN-1010 > 50 540 0.47 5.3 150

Nation NR 50 _ a 0 .003 no n-po ro us 0.8 200

Lewatit SPC 118 18 40 0.46 5.0 120

a Not applicable.

Anothe r method (adopted in our laboratory) 9. Reactions catalyzed by cation exchange

which may be more useful is as follows. The

resins Reactions of industrial importance

reaction is carried out for some time. The

resin phase is then carefully filtered off from All the reactions generally catalyzed by

the bulk solution. The co ntents of the resin mineral acids, can be carried out in the pres-

phase are th en elute d by some suitable sol- ence of cation exchange resin as catalyst with

vent and analyzed by the usual method . The some of the advantages which have been

bulk phase is then analyzed as usual. Thus by discussed earlier. The physical properties of

knowing the composition of the resin phase relevant cation exchange resins are listed in

and the bulk phase, the distribution coeffi- Table 1. A num ber of cation exchange resin

cient of the reactant s and the products can catalyzed processes have been commercial-

be fo und out. ized, a list is given in Tab le 2. Tab le 3 lists

TABLE 2

Some important commercial processes catalyzed by cation exchange resins

Name of the product Key reactants Ref.

Methyl

tert-butyl

ether (MTBE) Methanol + Isobutylene 77,133

Ethyl

tert-butyl

ether (ETBE) Ethanol + Isobutylene 77

tert-Amyl methyl ether (TAME) Methanol + Isoamylene 77

Isobutylene tert-Butanol 134-137

tert-Butanol

Isobutylene + Water 137

Isopropanol Propylene + Water 138-140

sec-Butanol

n-Butenes + Water 141, 142

Isopropyl esters Propylene + Carboxylic acids up to C20 143

sec-Butyl

acetate Butene + Acetic acid 144

sec-Butyl acrylate 1/2-Butene + Acrylic acid 145

Acrylates and Methacrylates Acrylic acid or Methacrylic acid + Alcohols 146-148

Alkylphenols Phenols + Olefins 149

Bisphenol A Phenol + Acetone 149

Methyl glucoside Dextrose + Methanol 150

Methyl isopropenyl ketone Methyl ethyl ketone + Formalin 151

Methyl isobutyl ketone Acetone + H 2 152


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A. C hakrabarti , M.M. Sharm a /Re ac t . Polym. 20 1993) 1-4 5

13

TABLE 3

Examples of the reactions catalyzed by cation exchange resins

Reaction System Catalyst Ref.

Aceta l format ion

Glyoxal + 3-Hydroxypropene Sulfonic acid resin 153

Formaldehyde + Methanol Lewatit SPC 118 104

Furfural + Ethylene glycol D61, D72 154

Benzophenone + Trimethyl orthoformate Nafion-H 155

Acetone

Butanone ~ + Methanol Dowex 50 3

Cyclohexanone]

[Ethylene glycol

Cyciohexanone + ~ 1,3-Propanediol Amberlyst-15 156

Alkylation of benzene / substituted benzene

Benzene + Ethylene Nation-H 157

Benzene + Propylene Amberlyst-15,

Dowex 50W-X2,

Dowex 50W-X4,

Dowex 50W-X12 34

Benzene + 1-Dodecene Amberlyst- 15,

Amberlyst XN-1010 158

m-Xylene + Isoprene Nafion-H 159

Benzene + Styrene Nation-H,

Amberlyst-15 42

Toluene + Styrene

idem.

42

p-Xylene + Styrene

idem.

42

o-Xylene + Styrene

idem.

42

m-Xylene + Styrene

idem.

42

1,2,4-Trimethylbenzene + Styrene idem. 42

1,3,5-Trimethylbenzene + Styrene

idem.

42

Toluene + p-Methylstyrene Nafion-H 42

m-Xylene + p-Methylstyrene

idem.

42

Alkylat ion of naphthalene

Naphthalene + Propylene Amberlyst-15 160

Alky lation o f phe nol / substituted phenols

Phenol + Ethylene Nafion-H 161

Phenol + Propylene Nation-H,

Amberlyst-15 161

Phenol + Isobutylene IB)

idem.

161

Phenol + Propylene Amberlyst-15, 43

Phenol + Butenes Amberlyst XN-010, 43

Phenol + IB Nation NR-50 43

Phenol + Isoamylene IA)

idem.

43

Phenol + 1-Octene

idem.

43

Phenol + Diisobutylene DIB)

idem.

43

Phenol + a-Methylstyrene

idem.

43

Phenol + a-Methylstyrene Amberlyst-15 163

Phenol + IB Sulfonic acid resin 162

Phenol + DIB Strongly acidic ion

exchanger 164


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14

A. Chakrabart i, M.M . Sharma / React . Polym. 20 1993) 1-4 5

T A B L E 3 ( c o n t in u e d )

Reac t ion Sys tem Ca ta lys t Ref .

Alkylation o f phenol / substituted phenols

Phenol + DIB Am ber lys t -15 ,

Am ber lys t XN-1010 165

Phenol + 1-Dodecene

idem.

165

Phenol + 1-Decene KU -2 166

Phen ol + C8_18 n-ole tins Sulfo-ba sed cation excha ngers 167

Phenol + P ropylen e t r imer Am ber lys t XN-1010 168

Phenol + Cyc lohexene Am ber lys t-15 ,

Amber l i te IR-120,

Na t ion NR-50 124

Phen ol + Styren e Na tion 117 169

Pyroga l lo l + S tyrene

idem.

170

Phenol + 1-Pentanol Wo fa t i t KPS 171

o-Cresol + 4-M ethyl - l -pe ntene Am ber lys t-15 172

m- C r e so l + I B N a t io n - H ,

Amberlyst-15 173

p-Creso l + IB Am ber lys t - 15 174

m- C r e so l /

p -Creso l /

2,5-Xylenol~ + AM S

idem.

100

2,4-Xylenol /

2,6-Xylenol}

m- C r e so l

p - C r e so l ~ + D I B

idem.

100

2,6-Xylenol )

Phenol /

o - C h lo r o p h e n o l

+ IB

idem.

7a

o - E th y lp h e n o l

G u a ia c o l

P h e n o l

o - C h l o r o p h e n o l | _ .

+ I A

idem.

7a

o - E th y lp h e n o l

Gua iacol )

P h e n o l + M T B E

idem.

44, 175

m- C r e so l + M T B E W o f a t i t O K - 8 0 1 76

Hyd roquino nes + IB Am ber lys t -15 177

Alkylation o f naphthols

a - N a p h th o l ~

t -Naphthol~ + IB

idem.

7a

a - N a p h th o l~ _ .

/3-Naphthol~ + IA

idem.

7a

Alkylation o f poly p-vinylphenol)

Poly(p-v inylphenol) +

tert-Butanol idem.

178

Alkylation o f phenylalkoxy- and hydroxy-benzoates

Phenylsa l icy la te + IB Wo fa t i t OK-80 179

Carbonylation

Form aldehy de ace ta l + Unspec i f ied comm erc ia l

Carbo n mon oxide ion exchanger 180


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A. Chakrabarti , M.M . Sharma /Rea ct . Polym. 20 1993) 1-4 5

15

TABLE 3 (continued)


Condensation

Methyl N-phenylcarbamate + Formaldehyde Cation exchange resin 181

Anethole + Acetaldehyde

idem.

182

Phenol + Acetone Revachit SPC-118 BG

(20 neutralized

with

H 2 N C H 2 C H z S H )

183

Phenol + Acetone Cation exchange resin 184-189

o-Benzoylbenzoic acid Sulfonic acid resin 190

1,4-Bis 2-propanol)benzene

+ Aniline Perfluorinated

sulfonic acid resin 191

Cyclohexanone Amberlite IR-120,

Dowex 50 192

to-Undecylenic acid Amberlyst- 15 193

Cross-dimerization

ot-p-Dimethylstyrene + IA

idem.

194

Cyanoethylation

Aniline + Acrylonitrile Strongly acidic resin 195

Decomp osition / cracking

MTBE Lewatit SPC 118, 65,

Amberlyst-15 196

TAME SiO2-modified

Lewatit SPC 118 197

Cumene hydroperoxide Amberlyst XN-1010,

Amberlite IR-118 127

p-tert-Butyl cum ene-hydroperoxide)

Vionit CS-1 198

Dim eriza ion / oligomeriza ion

IB Indion-130 199-201

IB Wofatit OK-80 202

IA Amberlyst-15, Polystyrene

sulfonic acid 203

1-Butene, 2-Butene Sulfonated polystyrene resin 204

DIB Macroporous cation

exchanger 205

Styrene Nafion-H,

Amberlyst-15 206-208

AMS Nafion NR-50,

Amberlyst-15, K2661,

Lewasorb AC 10 FT 209

Formaldehyde Ion exchange resin 210

Epoxidation

Ricebran oil + Hydrogen peroxide Strongly acidic

ion exchange resin 211

Cottonseed oil + Hydrogen peroxide Ion exchange resin 212

Esterification o f olefins

Propene +Acetic acid Lewatit SPC 213, 214

n-Butenes + Acetic acid KU-23 215

1-Butene

Isobutylene

1-Octene ] +Aceti c acid Amberlyst-15 95

1 - D o d e c e n e ]


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16 A. Chakrabarti, M.M. Sharma / React. Polym. 20 1993) 1-4 5

T AB L E 3 ( c on tinue d)

Rea ction System Catalyst Ref .

Esterification o f olefins

Cyclohexene + Acetic acid 001 x 7 (Cation exchanger) 216

Cyclohexene + Acetic acid Amberlyst-15 217

Cyclohexene + Acetic acid + water Lew atit SPC 118 218

/Fo rm ic acid Cation exchange resin 219

Cam phen e + ~Acetic ac id

Dihydrom yrcene + A cet ic ac id idem. 219

Styrene + Acetic acid Ostion KS 220

Styrene +A ceti c acid Amberlyst-15, Am berlyst

XN-1010, Nation NR -50,

Mon odisperse K2661,

K2631 221

Propy lene + Ch loroacetic acid Amberlyst-15 95

1-Butene + Acrylic acid Lew atit SPC 118 145, 222

Ca mp hen e + Methacrylic acid D001-ML 223

Dicy lopentad iene + Acetic acid Lew atit SPC 108 224

2_Methyl_l_butene Lew atit SPC

Isopren e ) + Acetic acid 118 (45

Cyclopentadiene ] neut ra l ized 225

with K + )

Pro py lene + My ristic acid Am berlyst-15 226

Esterification o f alcohols

I sopropanol + Acet ic ac id Dia ion HP K 55

(Modif ied to ge t

cor responding

f luor ina ted ion

exchange resin) 227

Hexyl alcohol + Acetic anh ydrid e Ion Exch anger 228

Glycerol +A cet ic anhydr ide EX 146H 229

fAce t ic ac id

Glycerol + ~Propionic acid D61, D7 2, Am berlyst-15 230

Eth ano l + Oxalic acid Am berli te IR-120 123, 231

C 6-12 Alc hls + Maleic anh ydrid e Vion it 232

M ethan ol + Methacrylic acid Cation exchange resin 233

2-Ethylhexanol + Methacrylic acid idem. 234

2-Ethylhexanol + Acrylic acid Dia ion PK 208 235

Ethy lene glycol )

Di-e thy lene glycol ~ Strongly acidic 236

Tri-ethylene glycol [ + Acrylic acid ion exchanger

Tetra-eth ylene glycol]

Me thanol + Fa t ty ac id Lewat i t 237

4-Oxo-pentanoic acid r)

c/s-Pinanoic acid

trans-Aconitic acid + M etha nol Amberlyst-15 238

( S) - M a nde l i c a c id

Oleic acid

Malonic ac id m onoethyl es te

Phe nol + Methacrylic acid idem. 239

Ring o pened adduct of cyanoethyl a lcohol

and e-Cap rolactone + Acrylic acid idem. 240


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A. C hakrabarti , M.M. Sharma /Re ac t . Polym. 20 1993) 1-4 5 17

T A BL E 3 c o n t in u e d )

Re act io n System Catalyst Ref.

Esterification of alcohols

Lip ids + Acet i c anhydr ide Cat ion exchange res in 241

Pyr role diacids + m ethan ol Am berl i te IR-120 242

Ethy lene g lycol H-fo rm ca t ion

mo noethy l e ther + Acet i c ac id exchanger 243

D i me t h y l p h o s p h o r a mi d o t h i o a t e

+ Ac et ic anhy dride Amberlyst -15 244

Tr ioxane + Carbon monox ide St rong ly ac id ic

+ me thano l ion exchanger 245

Etherification

IB + M ethano l Cat ion exchange res in 5 , 77 ,

246-261

IB + Eth ano l Am berlyst - 15, 77,

Amberlyst-35, 262,

Fluorocarbo n su l fon ic

acid 263

IA + M ethan ol Amberlyst -15 77, 264-2 66

2-M ethy l - l -bu tene + M ethano l Vion i t CS-34 267

IA + Eth ano l Amberlyst -15,

Amberlyst-35 267

IB + Eth ylen e glycol Acidic ion

exchange res in ,

Amberlyst -15 268-270

IB + Pro pylen e glycol Amberlyst -15 6, 271

E t h y l e n e

/ G l y c o l

1 -Butene + ~Propy lene idem. 270

| G l y c o l

I,Di -e thy lene g lycol e the r

E t h y l e n e

| G l y c o l

P r o p e n e + ~Pr o p y l e n e idem. 270

| G l y c o l

~Di -e thy lene g lyco l e ther

Dicy lopen tad iene + E thy lene g lycol idem. 272

[ E t h a n o l

Cam phene + ~Isopropano l Cat ion exchange res in 273

D i h y d r o my r c e n e + Me t h a n o l idem. 273

D I B

M ethy lpen tene + M ethano l Amber lys t-15 274

P i n e n e

a - P i n e n e ~

~ - P i n e n e ] + M e t h a n o l idem. 275

Cyc lohexen e + 2-Methyl-2-phenyl ethan ol idem. 276

Cyclohexene + Phene thy l a l coho l idem. 277

f Isoamyl alcohol

Sty rene + ~Cyclohexano l idem. 278

A M S + Me t h a n o l idem. 91


18/45

18

A. Chakrabart i, M.M. Sharma React. Polym. 20 (1993) 1-4 5

TABLE 3 continued)


E theri ic a tion

Phenol

IB + {a-Naphthol idem. 7a

~/3-Naphthol

Phenol

IA + {a-Naphthol

idem.

7a

~/3-Naphthol

Glucose + Methanol Nation 511, 150,

Amberlyst-15 279, 280

Methylolurea +

2-Methylpropanol Wofati t OK 80 281

Hydration

Propylene + Water Cation exchange resin 282

Propylene + Water Imac C8P 52

n-Butenes + Water XE-307 53

IB + Water Amberlyst-15,

Amberlyst XN-1010 84, 87, 283

Isopentenes + Water Amberlyst- 15,

Amberlyst XN-1010,

Lewatit SPC 118,

Lewatit SC 102 284-287

Camphene

a-Pinene

Dihydromyrcene + Water Cation exchange resin 288

Dipentene

Carene

Camphene + Water D001-ML, Strongly 289,

acidic ion exchange resin 290

Citronellol + Water Amberlyst-15 291

Cyclohexene + Water Lewatit SPC 118, 88-90,

Amberlite XE-307 218

AMS + Water Amberlyst-15,

Amberlite IR-120 91

Acrolein + Water Duolite C467, 292,

Amberlite ICR-718 293

Cyclohexene

oxide + Water Diaion-PK228 294b

2-Cyclohexenone + Water Ion exchanger

containing SO H

or NH4OH 294b

Acrylonitrile + Water Strongly acidic

ion exchanger

containing Cu ions 295

Hydrolysis

Methyl Acetate + Water Ion exchange resin 296

sec-Butyl-trifluoro

acetate + Water Nation NR 501 297

Ethylene glycol

mono-tert-butyl

ether + Water Amberlyst-15 298

Ethylene glycol

di-tert-butyl

ether + Water

idem.

299

Benzophe none

dimethyl acetal + Water Nation-H 155


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A. Chakrabarti , M.M. Sharma /R ea ct. Polym. 20 1993) 1-4 5 19

T A B L E 3 ( c o n t in u e d )

Reac t ion Sys tem Ca ta lys t Ref .

Hydrolysis

2,2-Dim ethyl- 1,3-dioxolane + W ater Am berlys t- 15 300

D i - me th y lp h o sp h o e n o lp y r u v a t e + W a te r D o w e x 5 0 H 3 01

Isomerization

endo-Dicyc lopentadiene Strong ac id ion exchanger 302

2-M ethy l- l-bu tene Sulfonic acid resin 303

1-Butene Ca t ion exchange re s in 304

2,5-Dimethylhexadienes Duo l i te C26H 305

Styrene oxide Na t ion 501 ,

Amberlyst-15 306

Epoxides Am ber l i te IR-120 307

2,4 -Dihydroxy -2 ,2 -d iphenylpropan e Dow ex MSC - 1 308

2,4 -Dihydroxy -2 ,2 -d iphenylpropan e Dow ex MSC - 1

conta in ing

(HSC H 2CH 2)2 N H 309

Mixture of 3-me thyl te t rahydroph

Documents

Chakrabarti 1993 Reactive-Polymers