Studies in Surface Science and Catalysis 24 - uni-muenchen.de · Studies in Surface Science and...

Studies in Surface Science and Catalysis 24

ZEOLITES Synthesis, Structure, Technology and Application

Proceedings of an International Symposium organized by the "Boris Kidric" institute of Chemistry, Ljubljana on behalf of the International Zeolite Association, Portoroz-Portorose, September 3-8, 1984

Editors

B. Drzaj, S. Hoöevar and S. Pejovnik »Boris Kidric« Institute of Chemistry, 61000 Ljubljana, Yugoslavia

ELSEVIER Amsterdam - Oxford - New York - Tokyo 1985

ν

CONTENTS

S t u d i e s i n S u r f a c e S c i e n c e and C a t a l y s i s X I

P r e f a c e X I Π

SYNTHESIS

S y n t h e s i s o f z e o l i t e s (R.M. B a r r e r ) ( P l e n a r y l e c t u r e ) 1

The s y n t h e s i s , c r y s t a l l i z a t i o n a n d s t r u c t u r e o f h e t e r o a t o m c o n t a i n i n g

ZSM-5 t y p e z e o l i t e (M-ZSM-5) (Xu Ruren a n d Pang Wenqin ( P l e n a r y

l e c t u r e ) 27

S y n t h e s i s o f ZSM-5 t y p e z e o l i t e s i n t h e s y s t e m ( N a , K )20 - A 1

20

3- S i 0

2-

H20 w i t h o u t and w i t h ΤPA Br ( A . N a s t r o , C. C o l e l l a a nd R. A i e l l o ) 39

C r y s t a l l i z a t i o n o f ZSM-5 t y p e z e o l i t e s f r o m r e a c t i o n m i x t u r e s f r e e o f

o r g a n i c c a t i o n s ( Ü . M . B e r a k and R. M o s t o w i c z ) 47

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

o f ( p o l y ) a l k y l mono- a n d d i a m i n e s ( Z . G a b e l i c a , M. C a v e z - B i e r m a n , P.

B o d a r t , A. G o u r g u e , and J.B. Nagy) 55

F a c t o r s i n f l u e n c i n g t h e c r y s t a l m o r p h o l o g y o f ZSM-5 t y p e z e o l i t e s

( R . M o s t o w i c z and J.M. B e r a k ) 65

The i n f l u e n c e o f a l k a l i m e t a l c a t i o n s on t h e f o r m a t i o n o f s i l i c a l i t e

i n NH^OH-TBAOH s y s t e m s ( T u Kungang and Xu R u r e n ) 73

T e m p l a t e v a r i a t i o n i n t h e s y n t h e s i s o f z e o l i t e ZSM-5 ( F . J . van d e r

Gaag, J.C. Jansen and H.van Bekkum) 81

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

( L i H o n g y u a n , L i a n g J u a n , Y i n g M u l i a n g and L i n B a o x i a n g ) 89

S y n t h e s i s o f s i l i c a - h i g h z e o l i t e s i n t h e p r e s e n c e o f s u r f a c t a n t s ( J .

B a t i s t a , B. D r z a j and A. Z a j c ) 97

S y n t h e s i s o f o f f r e t i t e - e r i o n i t e t y p e z e o l i t e f r o m s o l u t i o n phase ( S .

Ueda, M. N i s h i m u r a , a nd M. K o i z u m i ) 105

S t u d i e s on t h e t r a n s f o r m a t i o n b e t w e e n e r i o n i t e and o f f r e t i t e i n T - t y p e

z e o l i t e (Wang X i n g q i a o and Xu R u r e n ) 111

S y n t h e s i s and c h a r a c t e r i z a t i o n o f f a u j a s i t e - t y p e z e o l i t e s I I . The r o l e

o f a l k a l i c h l o r i d e s ( N . D e w a e l e , P. B o d a r t , Z. G a b e l i c a and J.B. Nagy) 119

A c o n t r i b u t i o n t o t h e s y n t h e s i s o f t h e l o w - s i l i c a X z e o l i t e (M. T a t i c

a n d B. D r z a j ) 129

V I

O p t i m i z a t i o n o f f a u j a s i t e s y n t h e s i s u s i n g f a c t o r i a l d e s i g n t e c h n i q u e

(M.K. T a n n o u s , M. H e l m y , F.H. K h a l i 1 and M.F. A b a d i r ) . . 137

S y n t h e s i s o f A, X and Y z e o l i t e s f r o m c l a y m i n e r a l s ( E . B . D r a g , A.

M i e c z n i k o w s k i , F. Abo-Lemon, M, R u t k o w s k i ) 147

S y n t h e s i s o f z e o l i t e A and Ρ f r o m n a t u r a l and w a s t e m a t e r i a l s ( C h .

S t a m b o l i e v , N. S o p o v a , K.-H. B e r g k and M. P o r s c h ) 155

On t h e r e a c t i o n m e chanism o f t h e f o r m a t i o n o f m o l e c u l a r s i e v e s and

r e l a t e d compounds ( E . W i e k e r and B. F a h l k e ) ( P l e n a r y l e c t u r e ) 161

A model f o r t h e c o m p u t a t i o n o f t h e s p e c i e s c o n c e n t r a t i o n s i n a q u e o u s

s i l i c a t e a nd a l u m i n o s i l i c a t e s o l u t i o n s ( J . - L . G u t h , P. C a u l l e t and

R. Wey) 183

The m e c h a n i s m o f t r a n s f o r m a t i o n o f NaY t o NaPc t y p e z e o l i t e s (Ma

S h u j i e , L i L i a n s h e n g , Xu Ruren and Y i e Z h a o h u i ) 191

K i n e t i c a n a l y s i s o f a u t o c a t a l y t i c n u c l e a t i o n d u r i n g c r y s t a l l i z a t i o n

o f z e o l i t e s ( B . S u b o t i c and A. G r a o v a c ) 199

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

A i n t o h y d r o x y s o d a l i t e ( B . S u b o t i c , N. M a s i c and I . S m i t ) 207

STRUCTURE DETERMINATION

Z e o l i t e s t r u c t u r e s : Some common m i s c o n c e p t i o n s and p i t f a l s (W.M.

M e i e r ) ( P l e n a r y l e c t u r e - e x t e n d e d a b s t r a c t ) 217

C h a r a c t e r i z a t i o n o f z e o l i t e c a t a l y s t s by MAS NMR (G.T. K o k o t a i l o , C A .

F y f e , G.C G o b b i , G.J. K e n n e d y , C T . D e s c h u t t e r , R.S. Ozubko and W.J.

M u r p h y ) ( P l e n a r y l e c t u r e ) 219

The i m p a c t o f new d i f f r a c t i o n t e c h n i q u e s i n z e o l i t e s t r u c t u r a l c h e ­

m i s t r y ( J . M . Newsam and D.E.W. Vaughan) 239

N e u t r o n d i f f r a c t i o n s t u d i e s o f t h e h y d r o g e n b o n d i n g and w a t e r m o l e c u l e s

i n z e o l i t e s (G.H. A r t i o l i , J.V. S m i t h , X . K v i c k , J . J . P l u t h and K.

S t a h l ) 249

On t h e i n f l u e n c e o f ( S i , A l ) d i s o r d e r on t h e T-0 d i s t a n c e s m e a s u r e d

i n z e o l i t e s ( A . A l b e r t i and G . G o t t a r d i ) 25.5

D e a l u m i n a t i o n o f Z e o l i t e s by v o l a t i l e r e a g e n t s . Mechanism o f and

s t r u c t u r a l c h a n g e s c a u s e d by d e a l u m i n a t i o n ( P . F e j e s , I . K i r i c s i ,

I . Hannus and Gy. S c h ö b e l ) 263

V I I

C r y s t a l s t r u c t u r e s o f r e l a t e d n o v e l a l u m i n o p h o s p h a t e f r a m e w o r k s :

A1P04-21 ( p y ) , A1P0

4-EN3 ( e n ) a n d a s t r u c t u r a l model f o r A l P 0

4- 2 5

( J . B . P a r i s e ) 271

IR s t u d y o f f r a m e w o r k v i b r a t i o n s a n d s u r f a c e p r o p e r t i e s o f h i g h s i ­

l i c a z e o l i t e s (Guo W e n g u i , L i a n g J u a n , L i H o n g y u a n , Y i n g M u l i a n g

and Hu J i e h a n ) 279

13

C n u c l e a r m a g n e t i c r e s o n a n c e s t u d y o f m o l e c u l e s a d s o r b e d on ZSM-5

and s i l i c a l i t e (W. M e i l e r and H. P f e i f e r ) 287

T h e o r e t i c a l a n d e x p e r i m e n t a l s t u d i e s on t h e s o r p t i o n o f g a s e s i n s i l i ­

c a l i t e ( A . T . J . H o p e , C.R.A. C a t l o w , C A . Leng and C.J. Adams) 297

S i l y l a t i o n o f H-ZSM-5.A TGA s t u d y ( R . Von B a l l m o o s and G.T. K e r r ) . . . 307

S u r f a c e p r o p e r t i e s o f p h o s p h o r u s and magnesium m o d i f i e d ZSM-5 z e o l i ­

t e s ( C a i G u a n g y u , Chen G u o q u a n , Wang Q i n g x i a , X i n Q u i n , Wang

X i a n g z h e n , Wang Z u o z h o u , L i X i y i a o and L i a n g J u a n ) 319

Pore s i z e e n g i n e e r i n g i n z e o l i t e s ( E . F . V a n s a n t , G. P e e t e r s , A. T h i j s

and I . V e r h a e r t ) 329

The r m a l s t a b i l i t y o f m o r d e n i t e s w i t h v a r i o u s S i O ^ / A l ^ O ^ r a t i o s ( I .

T s o l o v s k i , C h r . M i n c h e v , E.E. S e n d e r o v and V. P e n c h e v ) 337

The t h e r m o d e s o r p t i o n k i n e t i c s o f w a t e r f r o m m o r d e n i t e ( V . Dondur a n d

R. D i m i t r i j e v i c ) 345

S p e c t r o s c o p y o f Cu ( I I ) c o o r d i n a t e d t o l a t t i c e o x y g e n s i n z e o l i t e s

( D . P a c k e t , W. D e h e r t o g h and R.A. S c h o o n h e y d t ) 351

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

f r o m Z l a t o k o p ( V r a n j e ) , Y u g o s l a v i a ( T . c e r a n i c , D. V u c i n i c , B . D r z a j

and S .Hocevar) 359

S t u d y o f t h e p r o p e r t i e s o f c l i n o p t i l o l i t e m o d i f i e d by t r a n s i t i o n me­

t a l i o n s ( A . S p o j a k i n a , I . T s o l o v s k i , N. K o s t o v a , T.Popov, S . K r u s t e v

and D. Shopov) 367

Cuban n a t u r a l z e o l i t e s : M o r p h o l o g i c a l s t u d i e s by e l e c t r o n m i c r o s c o p y

(G.R. F u e n t e s , C L . S a n c h e z , J . C Romero and K.R. M a l h e r b e ) 375

E f f e c t o f t h e d e a l u m i n a t i o n o f Y - t y p e z e o l i t e s on t h e i r w e t t i n g

p r o p e r t i e s ( I . D e k a n y , F. S z ä n t o a n d H.K. B e y e r ) 385

H y d r o t h e r m a l b e h a v i o u r o f Z e o l i t e s i n FCC c a t a l y s t s ( I . H a l a s z , J .

H o r v ä t h , Τ. M ä n d y , L . S c h m i d t a n d E. T a s n a d y ) 393

V I I I

H y d r o t h e r m a l a g e i n g o f c r a c k i n g c a t a l y s t s . I . - E v a l u a t i o n o f t h e

c r y s t a l l i n e f r a c t i o n o f z e o l i t e s ( F . Mauge, J.C. C o u r c e l l e , Ph.

E n g e l h a r d , P. G a l l e z o t , J . G r o s s m a n g i n , M. P r i m e t and B. T r u s s o n ) . . . 4C1

M a t r i x e f f e c t s on t h e M i C O ^ + C O1

^ M ( C 0 ) ^ e q u i l i b r i u m e x p e r i e n c e d

by m o n o v a l e n t r h o d i u m and i r i d i u m c a r b o n y l s i n z e o l i t e s ( F . L e f e -

b v r e , A. A u r o u x and Y. Ben T a a r i t ) 4 1 1

P r e p a r a t i o n o f i r o n ( O ) model c a t a l y s t s w i t h i r o n c l u s t e r s o f sub-nm

d i m e n s i o n s by d e c o m p o s i t i o n o f Y - z e o l i t e a d s o r b e d i r o n p e n t a c a r b o n y l

( T h . B e i n , F. S c h m i d t and P.A. J a c o b s ) 419

Gas c h r o m a t o g r a p h i c s o r p t i o n s t u d i e s o f h y d r o c a r b o n s i n N-A-type

z e o l i t e s w i t h d i f f e r e n t S i / A l - r a t i o s ( H . L e c h e r t and W. S c h w e i t z e r ) . 427

2+

The Cu i o n m i g r a t i o n i n t h e CuNaX z e o l i t e (Wei G u o x i a n g , Ye

H u j u a n , L ü G u a n g l i e , L i u Z h e n g y i , Song Deyu and L i n B i n g x i o n g ) 435

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

F o m k i n , I . I . S e l i v e r s t o v a and V.V. S e r p i n s k y ) 4 43

C r y s t a l s t r u c t u r e and mechanism o f A g+

e x c h a n g e on NaA.NaNO^

i n c l u s i o n c o m p l e x o f z e o l i t e A ( R . D i m i t r i j e v i c , N. P e t r a n o v i c ,

I . K r s t a n o v i c , M. S u s i e and U. M i o c ) 4 5 3

R e s o l u t i o n o f oL -and / 3 - c a g e d e c a p s u l a t i o n p e a k s i n t h e t e m p e r a t u r e

programmed d i f f u s i o n (TPD) o f n o n - p o l a r g a s e s i n Cs, Na-A ( D . F r a e n k e l ,

B. I t t a h and M. L e v y ) 459

O r d e r e d d i s t r i b u t i o n o f c a t i o n s i n z e o l i t e A ( T . T a k a i s h i , T. Ohgushi

an d K. Nonaka) '. 467

H e a t c a p a c i t i e s o f w a t e r i n z e o l i t e s ( V . V u c e l i c and D. V u c e l i c ) - 475

G i s s m o n d i n e : The d e t a i l e d X - r a y s t r u c t u r e r e f i n e m e n t o f two n a t u r a l

s a m p l e s ( R . R i n a l d i and G. V e z z a l i n i ) 481

F a c t o r s a f f e c t i n g a c i d i t y and b a s a l s p a c i n g o f c r o s s - l i n k e d

s m e c t i t e s ( L i u Z h o n g h u i and Sun G u i d a ) 493

TECHNOLOGY AND APPLICATION

N a t u r a l z e o l i t e s : P r o c e s s i n g , p r e s e n t and p o s s i b l e a p p l i c a t i o n s

( R . S e r s a l e ) ( P l e n a r y l e c t u r e ) 503

C h e m i c a l t r e a t m e n t o f n a t u r a l z e o l i t e s , and p r o p e r t i e s and u t i l i z a ­

t i o n s o f t h e r e a c t e d m a t e r i a l s ( H . M i n a t o ) 513

I X

N a t u r a l z e o l i t e s as c o n s t i t u e n t s o f b l e n d e d c e m e n t s ( R . S e r s a l e and

G. F r i g i o n e ) 523

Use o f c l i n o p t i l o l i t e i n p a p e r i n d u s t r y as f i l l e r o f p a p e r ( Z h a n g

Q u a n c h a n g , Su M i n q d i , Dai C h a n g l u , Yang H u a r u i , Zhang Q i x i n g and

Zhang Z h i g u o ) 531

Ammonia r e m o v a l f r o m m u n i c i p a l w a t e r by p h i l l i p s i t e ( P . C i a m b e l l i ,

P. C o r b o , L. L i b e r t i , A. Lopez a n d C. P o r c e l l i ) 539

χ A p p l i c a t i o n o f n a t u r a l z e o l i t e s i n r e f r i g e r a t i o n ( S . L . Z h u k o b o r s k y ) . . 547

E n e r g y s t o r a g e i n z e o l i t e s a n d a p p l i c a t i o n t o h e a t i n g and a i r c o n d i t i -

} ^ o n i n g ( D . J u n g , N. K h e l i f a , E. Lavemann and R. S i z m a n n ) 7.' 1

555

The r e l e a s e o f t r i t i a t e d w a t e r f r o m z e o l i t e s i n t o s u r r o u n d i n g w a t e r

563

( M . T o d o r o v i c , I . J . Gal and I . P a l i g o r i c ) ^

S o d i u m t r i p h o s p h a t e r e p l a c e m e n t by b u i l d e r s y s t e m s i n d e t e r g e n t s ( L .

G a b r o v s e k ) * 571

S y n t h e s i s o f z e o l i t e A f r o m s i l i c a t e raw m a t e r i a l s and i t s a p p l i c a t i o n

i n f o r m u l a t i o n s o f d e t e r g e n t s ( S . D o n e v s k a , J . T a n e v s k i and N.

D a s k a l o v a ) 579 "

Some r h e o l o g i c a l a nd t r a n s p o r t p r o p e r t i e s o f z e o l i t e s u s p e n s i o n s

( V . G r i l c and B. D r z a j ) 5 8 5 - ^

Z e o l i t e s NaHA and CaHA as t o o t h p a s t e a b r a s i v e s ( E . P . H e r t z e n b e r g

a n d A.L. D e n t ) 589

\ P r e s s u r e s w i n g a d s o r p t i o n on 4A a n d 5A z e o l i t e (N.S. R a g h a v a n , M.M.

N

Hassan and D.M. R u t h v e n ) 597

w Z e o l i t e s as a d s o r b e n t s f o r a l c o h o l s f r o m aqueous s o l u t i o n s (G.S.

' Haegh) 605 7

H i g h s i l i c a z e o l i t e as h e t e r o g e n e o u s c a t a l y s t ( L i a n g J u a n ) ( P l e n a r y

l e c t u r e ) 611

Z e o l i t e Nu-3: I t s s y n t h e s i s , c h a r a c t e r i s a t i o n and use i n m e t h a n o l

c o n v e r s i o n ( J . L . C a s c i and T.V. W h i t t a m ) 623

C a t a l y t i c p r o p e r t i e s o f ZSM-11 and ZSM-5 z e o l i t e s ( G . G i a n n e t t o ,

G. P e r o t and M. G u i s n e t ) 631

I n i t i a t i n g e f f e c t o f C2

+

o l e f i n s and a l c o h o l s on t h e t r a n s f o r m a t i o n s

o f m e t h a n o l on c r y s t a l l i n e and amorphous a l u m i n o s i 1 i c a t e s ( S . D z w i g a j ,

J . Haber and M. D e r e w i n s k i ) 6 3 9

χ

IR s t u d y o f t h e c i s - t r a n s i s o m e n ' z a t i o n o f o l e f i n s on H-ZSM-5

z e o l i t e ( C P . B e z o u h a n o v a , C. D i m i t r o v , E. K h a l i l o v and H.

L e c h e r t ) 647

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

p r o c e s s ( N . J o v a n o v i c , D. S k a l a , Μ. M a r j a n o v i c , Μ. S t a n k o v i c and

T. Z e r a r k a ) 653

N i c k e l a n d / o r molybdenum c o n t a i n i n g z e o l i t e s as c a t a l y s t s f o r

h y d r o d e s u l f u r i z a t i o n ( N . D a v i d o v a , P. Kovac h e v a and D. S h o p o v ) 6 5 9

: T r a n s a l k y l a t i o n o f t o l u e n e w i t h t r i m e t h y l b e n z e n e s o v e r n i c k e l

s u p p o r t e d t y p e L - z e o l i t e c a t a l y s t ( A . B . H a l g e r i a nd T.S.R. Prasada

Rao) 667

K i n e t i c s o f n-hexane i s o m e r i z a t i o n on P t / L a - f a u j a s i t e c a t a l y s t s

(M. Kh. J a n n o u s , Ch. M a r c i l l y and F.M. K h a l i l ) 675

Low a r o m a t i c s o l v e n t s t h r o u g h d e a r o m a t i z a t i o n on m o l e c u l a r s i e v e

13 X ( D . A h m e t o v i c and S. S v e l - C e r o v e c k i ) 6 83

419

Β. Drzaj. S. Hocevar and S. Pejovnik (Editors), Zeolites © 1985 Elsevir Science Publishers Β. V. Amsterdam - Printed in Yugoslavia

PREPARATION OF IRON(O) MODEL CATALYSTS WITH IRON CLUSTERS OF SUB-NM DIMENSIONS

BY DECOMPOSITION OF Y-ZEOLITE ADSORBED IRON PENTACARBONYL

T h . B E I N1

, F. SCHMIDT1

and P.A. JACOBS2

ι

I n s t i t u t f ü r P h y s i k a l i s c h e Chemie d e r U n i v e r s i t ä t H amburg, L a u f g r a b e n 2 4 ,

D-2000 Hamburg 13 (F.R.G.)

2

L a b o r a t o r i u m v o o r O p p e r v l a k t e s c h e i k u n d e , K a r d i n a a l M e r c i e r l a a n , 9 2 ,

B-3030 H e v e r l e e ( B e l g i u m )

ABSTRACT

T h e r m a l d e c o m p o s i t i o n i n a s h a l l o w bed o f i r o n p e n t a c a r b o n y l a d s o r b e d on

N a Y - z e o l i t e i s a c h i e v e d u n d e r vacuum a l r e a d y a t 370 Κ w i t h l o w h e a t i n g r a t e s .

D e c o m p o s i t i o n u n d e r f a s t h e a t i n g i n i n e r t gas and f l u i d i z e d s h a l l o w bed c o n ­

d i t i o n s can be c o m p l e t e d w i t h i n a f e w m i n u t e s a t c a . 500 K. Z e o l i t e s u p p o r t e d

i r o n c l u s t e r s o b t a i n e d by t h e s e t e c h n i q u e s a r e c h a r a c t e r i z e d v i a e v a l u a t i o n o f

t h e r e s p e c t i v e m a g n e t i c i s o t h e r m s t a k e n w i t h a F o n e r m a g n e t o m e t e r a t 4.2 K.

Low t e m p e r a t u r e / v a c u u m as w e l l as h i g h t e m p e r a t u r e / i n e r t gas t h e r m o l y s i s g i v e s

i r o n c l u s t e r s y s t e m s w i t h a t l e a s t 70 t o 90 w t - % s m a l l e r t h a n 1 nm.

INTRODUCTION

S e v e r a l e f f o r t s have been made i n o r d e r t o i n v e s t i g a t e p a r t i c l e s i z e e f f e c t s

1 2 3 4 i n c a t a l y s i s ' ' . I n p a r t i c u l a r , i r o n s y s t e m s used i n ammonia s y n t h e s i s and

5 C 0 - h y d r o g e n a t i o n r e a c t i o n s a r e o f i n d u s t r i a l i n t e r e s t .

S i n c e z e o l i t e s a r e c r y s t a l l i n e and have w e l l d e f i n e d p o r e s t r u c t u r e , v a r i ­

a b l e e l e c t r o n i c ^ and s o l v o l y t i c p r o p e r t i e s , t h e y a r e s u i t a b l e s u p p o r t s f o r

model c a t a l y s t s .

I n attempt to overcome d i f f i c u l t i e s i n the preparation of iron zeolites by c l a s s i c a l r e d u c t i o n t e c h n i q u e s s u c h as d e c r e a s e d r e d u c i b i l i t y o f i r o n e x c h a n g e d

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

t h e d e c o m p o s i t i o n o f p r e a d s o r b e d i r o n p e n t a c a r b o n y l was s t u d i e d i n d e t a i l ^ . The

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

n a r r o w p a r t i c l e s i z e d i s t r i b u t i o n .

A d s o r p t i o n e q u i l i b r i u m b e t w e e n F e ( C 0 ) r and d i f f e r e n t l a r g e p o r e z e o l i t e s

8 9

was s t u d i e d by g r a v i m e t r i c and I R - s p e c t r o s c o p i c t e c h n i q u e s ' , w h e r e a s t h e r m a l

d e c o m p o s i t i o n was f o l l o w e d by t h e r m o g r a v i m e t r i c and I R - s p e c t r o s c o p i c1

^ m e t h o d s .

11

The e f f e c t o f p r e p a r a t i o n c o n d i t i o n s on i r o n p a r t i c l e s i z e w i l l be r e p o r t e d

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

r a t e s i n a f l u i d i z e d s h a l l o w bed r e a c t o r on i r o n p a r t i c l e s i z e w a s s t u d i e d by

m a g n e t i c m e t h o d s .

420

EXPERIMENTAL

M a t e r i a l s

S y n t h e t i c NaY(FAU) w i t h S i / A l = 2.46 f r o m S t r e m C h e m i c a l s was t r e a t e d w i t h

0.1 Μ NaCl s o l u t i o n , w a s h e d , a i r - d r i e d and s t o r e d o v e r s a t u r a t e d NH^Cl s o l u ­

t i o n t o e n s u r e c o n s t a n t h u m i d i t y . B e f o r e l o a d i n g w i t h F e ( C 0 ) r , t h e z e o l i t e was

-3 d e g a s s e d i n t h e r e a c t o r a t 670 Κ f o r 36 ks a t 10 Pa, w i t h a h e a t i n g r a t e o f

_ ι

0.033 Ks . I r o n p e n t a c a r b o n y l f r o m V e n t r o n ( 9 9 . 5 % ) was c o l d l y d i s t i l l e d i n t h e

d a r k and s t o r e d i n a s t a i n l e s s s t e e l t u b e o v e r m o l e c u l a r s i e v e 5A.

Gas d o s i n g s y s t e m and r e a c t o r

A s t a i n l e s s s t e e l gas d o s i n g s y s t e m w i t h m e t a l / v i t o n v a l v e s , c o n n e c t e d t o a

q u a r t z r e a c t o r , a l l o w e d ^ c o n t r o l l e d d e g a s s i n g o f t h e h y d r a t e d z e o l i t e s u n d e r

h i g h vacuum ( 1 0 P a ) , l o a d i n g o f t h e z e o l i t e s w i t h p u r i f i e d d r y v a p o r o f

F e ( C O ) ^ , t h e r m a l and p h o t o c h e m i c a l d e c o m p o s i t i o n o f t h e a d d u c t s i n a s h a l l o w

f l u i d i z e d bed and s a m p l e p r e p a r a t i o n i n i n e r t a t m o s p h e r e f o r m a g n e t i c m e a s u r e ­

m e n t s and M ö s s b a u e r s p e c t r o s c o p y .

A f t e r c o o l i n g 180 - 450 mg o f d e h y d r a t e d z e o l i t e i n t h e q u a r t z r e a c t o r w i t h

a 20 χ 50 mm h o r i z o n t a l bed s e c t i o n , i r o n c a r b o n y l was f r o z e n i n l i q u i d a i r ,

d e g a s s e d and a l l o w e d t o warm up t o 273 K, and f i n a l l y c o n t a c t e d w i t h t h e z e o ­

l i t e s a m p l e . An e q u i l i b r i u m p r e s s u r e o f 870 Pa s a t u r a t e d t h e z e o l i t e p o r e

9

s y s t e m . A f t e r 14 k s , t h e s y s t e m was e v a c u a t e d f o r one h o u r . S u b s e q u e n t l y , t h e

a d d u c t s w e r e decomposed t h e r m a l l y u n d e r vacuum o r i n h e l i u m g a s , u s i n g a v e r y

f a s t h e a t i n g p r o c e d u r e ( " s h o c k " h e a t i n g ) . The l a t t e r was a c h i e v e d by d i p p i n g

t h e f r o z e n r e a c t o r i n t o a m e t a l b a t h a t 490 K. i

The f l u i d i z e d bed was g e n e r a t e d by a h o r i z o n t a l v i b r a t i o n o f t h e r e a c t o r

w i t h ν = 50 Hz and a b o u t 1 mm a m p l i t u d e .

M a g n e t i z a t i o n m e a s u r e m e n t s

A b o u t 20 mg o f i r o n z e o l i t e s a m p l e was p r e s s e d w i t h a q u a r t z r o d i n t o a

q u a r t z t u b e ( 2 . 5 mm d i a m e t e r ) u n d e r v a c u u m , s e a l e d o f f and i n t r o d u c e d i n t o t h e

h e l i u m c r y o s t a t e ( J a n i s ) o f a F o n e r v i b r a t i n g s a m p l e m a g n e t o m e t e r ( P . A . R . ) .

The m a g n e t i z a t i o n c u r v e was t a k e n a t 4.2 Κ i n m a g n e t i c f i e l d s up t o 6 T.

The m a g n e t o m e t e r was c a l i b r a t e d w i t h a p u r e Ni m e t a l s a m p l e and c o r r e c t i o n s

f o r s a m p l e h o l d e r and q u a r t z t u b e w e r e t a k e n i n t o a c c o u n t .

M o s t s a m p l e s d i d n o t show h y s t e r e s i s . T h e r e f o r e , t o a f i r s t a p p r o x i m a t i o n ,

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

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

a t t a i n m e n t o f s p i n e q u i l i b r i u m , p a r t i c l e a n i s o t r o p y , p a r t i c l e i n t e r a c t i o n a nd

c h e m i c a l l y i n h o m o g e n e o u s phases c an be n e g l e c t e d .

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

12 13 t h e r m s by a sum o f d i f f e r e n t L a n g e v i n - o r B r i l l o u i n - f u n c t i o n s g i v e s a p p r o -

421

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

q u a n t u m n u m b e r s , I , r e s p e c t i v e l y .

The B r i l l o u i n f u n c t i o n

B j ( x ) = M/M^ = 2 I

2| - c o t h

2 I

2* 1

χ - c o t h x ,

w i t h χ = ΙςμβΒ/kT a p p l i e s to p a r t i c l e s w i t h a s m a l l m a g n e t i c moment.

(M = m a g n e t i z a t i o n , = s a t u r a t i o n m a g n e t i z a t i o n , I = c l u s t e r s p i n q u a n t u m

n u m b e r , g = Lande f a c t o r , μ^ = B o h r ' s m a g n e t o n , Β = m a g n e t i c f i e l d , k = B o l t z -

mann's c o n s t a n t , Τ = t e m p e r a t u r e )

I n attempt to obtain the saturation m a g n e t i z a t i o n Μ , t h e i r o n c o n t e n t o f t h e

s a m p l e s was d e t e r m i n e d by X - r a y f l u o r e s c e n c e and n e u t r o n a c t i v a t i o n t e c h n i q u e s .

The t o t a l r e l a t i v e e r r o r i n i r o n w e i g h t i s + 1 5 % .

RESULTS AND DISCUSSION _ ι

D i f f e r e n t h e a t i n g r a t e s i n t h e r a n g e b e t w e e n 0.0025 and a b o u t 10 Ks were

u s e d d u r i n g t h e r m o l y s i s o f c a r b o n y l / F A U - a d d u c t s .

The s a m p l e t o w h i c h t h e s l o w e s t h e a t i n g r a t e was a p p l i e d ( F A U / 0 . 0 0 2 5 ) , was

t r e a t e d i n a s t a t i c bed u n d e r v a c u u m , b e c a u s e v e r y s l o w h e a t i n g u n d e r i n e r t gas

c o n d i t i o n s may g i v e an i n h o m o g e n e o u s l y d i s t r i b u t e d i r o n p h a s e .

A l l o t h e r s a m p l e s w e r e decomposed u n d e r f l u i d i z e d b ed c o n d i t i o n s i n h e l i u m

a t m o s p h e r e . The r e s p e c t i v e d e c o m p o s i t i o n p a r a m e t e r s a r e g i v e n i n t a b l e 1 . The

r a t e and d e g r e e o f d e c o m p o s i t i o n c an be m o n i t o r e d f o l l o w i n g t h e gas p r e s s u r e .

TABLE 1 . T h e r m o l y s i s o f F e ( C 0 )5/ F A U - a d d u c t s u n d e r f l u i d i z e d s h a l l o w bed

c o n d i t i o n s3

Sample H e a t i n g F i n a l H e a t i n g H e l i u m - O u t g a s s - I r o n Amount

r a t e / Temp. p e r i o d a t p r e s s u r e b

m g c o n t e n t CO/%

Ks '1

Τ /Κ max W

k s /kPa ks / w t - %

F / 0 . 0 0 2 5d

0.0025 373 18 10"2

Pa 5.2 _

F/0.33 0.33 490 0.24 48 50 5.3 88

F/S c a . 10 490 0.36 80 54 3.9 88

a

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

.185 t o 444 mg. -

°At 373 Κ and 1 0 "J

Pa.

Amount o f CO g e n e r a t e d w i t h r e s p e c t t o t h e t h e o r e t i c a l amount e x p e c t e d f o r an

i n i t i a l l o a d i n g o f 30 w t - % Fe(CO),-.

d T h i s s a m p l e was decomposed u n d e r s t a t i c bed c o n d i t i o n s .

-1 R e p r e s e n t a t i v e p r e s s u r e c u r v e s o b t a i n e d a t d e c o m p o s i t i o n r a t e s o f 0.33 Ks

422

( s a m p l e F/0.33) and " s h o c k " h e a t i n g ( s a m p l e F / S ) , r e s p e c t i v e l y , a r e shown i n

f i g . 1 .

100-1

F i g . 1 . Gas e v o l u t i o n c u r v e s d u r i n g t h e r m a l d e c o m p o s i t i o n o f Fe(C0)^/FAU-

a d d u c t u n d e r f l u i d i z e d bed c o n d i t i o n s . _ 1

A, w i t h a h e a t i n g r a t e o f 0.33 Ks , s a m p l e F/0.33;

B, w i t h s h o c k h e a t i n g ( s a m p l e F / S ) ; p a r a m e t e r s see t a b l e 1 .

I n t h e f i r s t c a s e , t h e gas e v o l u t i o n r a t e c l e a r l y a l l o w s us to divide the de-c a r b o n y l a t i o n p r o c e s s i n t o t h r e e d i s t i n c t r e g i o n s : t w o z o n e s of s l o w gas e v o ­

l u t i o n a r e s e p a r a t e d . b y a f a s t r e a c t i o n ( f i g . 1 a ) . The l a t t e r i s a c c o m p a n i e d

by t h e t y p i c a l c o l o r c h a n g e f r o m i v o r y - l i k e t o b l a c k .

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

p e r i m e n t s w i t h s i m i l a r F e ( C 0 )5/ z e o l i t e a d d u c t s ' and c o n f i r m s i n d e p e n d e n t l y

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

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

b o n y l c l u s t e r s .

I f i n c o n t r a s t t h e a d d u c t i s h e a t e d by a t e m p e r a t u r e s h o c k , t h e s l o w gas

e v o l u t i o n p r i o r t o t h e m a i n r e a c t i o n i s m i s s i n g ( f i g . 1 b ) .

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

s t i o n o c c u r s i n a r e p r o d u c i b l e and c o m p l e t e manner ( t a b l e 1 ) , i r r e s p e c t i v e o f

t h e h e a t i n g r a t e and t h e amount o f s a m p l e .

C h a r a c t e r i z a t i o n o f t h e t h e r m a l l y decomposed s a m p l e s was done v i a e v a l u a -

423

t i o n o f t h e r e s p e c t i v e m a g n e t i z a t i o n c u r v e s a t Τ = 4.2 K. A r e p r e s e n t a t i v e

c u r v e ( F / 0 . 3 3 ) i s d e p i c t e d i n f i g . 2 , w h e r e a s t h e r e s u l t s f o r o t h e r s a m p l e s

a r e g i v e n i n t a b l e 2 . As can be seen f r o m t a b l e 2 , i n m o s t c a s e s one s i n g l e

magnetic f i e l d / Τ

F i g . 2 . M a g n e t i z a t i o n c u r v e o f s a m p l e F/0.33 a t Τ = 4.2 Κ, f i t t e d by one

B r i l l o u i n f u n c t i o n w i t h I = 3 6 . P a r a m e t e r s see t a b l e 1 and 2 .

B r i l l o u i n f u n c t i o n s u f f i c e s t o f i t t h e e x p e r i m e n t a l m a g n e t i z a t i o n c u r v e . Under

t h e a s s u m p t i o n s m e n t i o n e d i n t h e e x p e r i m e n t a l s e c t i o n , t h e r e s u l t s a l l o w us to

c o n c l u d e t h e f o l l o w i n g :

- T h e r m o l y s i s o f F e ( C O ) ^ / F A U - a d d u c t s g i v e s i r o n p a r t i c l e s y s t e m s w i t h s u p e r ­

p a r a m a g n e t i c b e h a v i o r . In attempt to determine the mass f r a c t i o n o f t h e s u p e r ­

p a r a m a g n e t i c p a r t i c l e s , t h e e x p e r i m e n t a l s a t u r a t i o n m a g n e t i z a t i o n Μ was

6 -1 °sexp r e l a t e d t o t h e b u l k v a l u e ( M

o o(4.2 K) = 1.752-10 Am ) . The s u p e r p a r a m a g n e t i c

f r a c t i o n q = Μ /Μ i s f o u n d t o be 1 0 0 % , w i t h i n t h e e r r o r o f t h e i r o n c o n -°°,exp co

t e n t , f o r a l l s a m p l e s .

- The m a i n f r a c t i o n o f t h e p a r t i c l e s y s t e m shows m a g n e t i c moments c o r r e s p o n d ­

i n g t o c l u s t e r s w i t h l i n e a r d i m e n s i o n s b e l o w 1 nm.

- The mean c l u s t e r s i z e seems t o be n e a r l y i n d e p e n d e n t o f t h e h e a t i n g r a t e

a p p l i e d t o t h e f l u i d i z e d s h a l l o w bed ( s a m p l e s F / 0 . 1 7 , F / 0 . 3 3 , F / S ) . I t can be

assumed t h a t f a s t h e a t i n g u n d e r i n e r t gas p r e v e n t s t h e s a m p l e s e f f e c t i v e l y

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

424

used t o c o m p l e t e t h e d e c o m p o s i t i o n .

- I r o n c l u s t e r s i z e s o b t a i n e d by v e r y s l o w h e a t i n g up t o 373 Κ u n d e r vacuum

( s a m p l e F/0.0025) a r e c o m p a r a b l e t o t h o s e o f t h e i n e r t g a s / f a s t h e a t i n g

s a m p l e s d i s c u s s e d a b o v e .

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

f r a c t i o n s o f m a g n e t i c a l l y b l o c k e d p a r t i c l e s , w h i c h s t i l l do n o t change s i g n i ­

f i c a n t l y t h e s a m p l e ' s m a g n e t i z a t i o n c u r v e a t Τ = 4.2 Κ. A t t h i s t e m p e r a t u r e ,

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

o f g r e a t e r p a r t i c l e s ( i . e . g r e a t e r t h a n a b o u t 3 nm) b e l o w 20 w t - % . S i n c e

t h e s e p a r t i c l e s c o n t a i n more t h a n 10^ a t o m s , t h e i r t o t a l number s h o u l d be

n e g l i g i b l e .

A d d i t i o n a l c h a r a c t e r i z a t i o n o f t h e i r o n / z e o l i t e s y s t e m s was o b t a i n e d i n a

19

r e c e n t M o s s b a u e r s p e c t r o s c o p i c s t u d y . A t y p i c a l b u l k i r o n h y p e r f i n e s p l i t t ­

i n g o f c o m p a r a b l e s a m p l e s a t room t e m p e r a t u r e i n d i c a t e s t h a t s p i n e q u i 1 i b r i u m

-9 i s n o t a t t a i n e d i n t h e t i m e d o m a i n o f t h e M o s s b a u e r e f f e c t ( 1 0 s ) .

TABLE 2 . C l u s t e r s p i n q u a n t u m number d i s t r i b u t i o n o f t h e r m a l l y decomposed

F e ( C 0 ) ^ / F A U - a d d u c t s , d e r i v e d f r o m B r i l l o u i n - f i t s .

Sample Ia

Number o f

a t o m sb

/ Ν

p a r t i c l e s i z ec

V1 / 3

/nm

w e i g h t f r a c t i o ne

/

%

q - v a l u e /

%

F/0.0025 35 35 0.74 100 107

F/0.33 36 36 0.75 100 111

F/S 43 43 0.80 100 117

a 14 ^A L a n d e - f a c t o r g = 2.06 was used i n t h e a r g u m e n t o f t h e B r i l l o u i n f u n c t i o n .

cT h e number o f atoms e q u a l s I , s i n c e t h e value of 1=1 p e r a t o m was a s s u m e d .

P a r t i c l e s i z e was c a l c u l a t e d a s s u m i n g bcc s t r u c t u r e and a t o m i c r a d i u s o f i r o n

dt o be R = 0.124 nm, a c c o r d i n g t o V

1 / 3

= 0 . 2 2 7 · Ν1 / 3

w i t h Ν = number o f a t o m s1 5

.

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

Μ as d e r i v e d f r o m t h e B r i l l o u i n f i t and t h e b u l k v a l u e Μ ( 4 . 2 Κ) = °°,exp c ι

0 0

e1 . 7 5 2 . 1 0° Am*"

1

.

Mass f r a c t i o n o f t h e r e s p e c t i v e d i s c r e t e p a r t i c l e s i z e f r a c t i o n .

The p r e s e n c e o f a c e r t a i n amount o f larger p a r t i c l e s c o u l d be d e t e c t e d

i n d e p e n d e n t l y by X - r a y d i f f r a c t i o n m e t h o d s . A w e a k , b r o a d l i n e was f o u n d w i t h

t h e d - v a l u e o f t h e ct-Fe d ^ Q - l i n e . L i n e b r o a d e n i n g a l l o w e d us to estimate the

mean p a r t i c l e s i z e o f t h i s f r a c t i o n t o be <T = 30 n m ± 2 0 nm - i n c l u d i n g Gauss-

and C a u c h y - l i n e p r o f i l e i n t o t h e c a l c u l a t i o n . T r a n s m i s s i o n e l e c t r o n m i c r o ­

g r a p h s o f c o m p a r a b l e s a m p l e s i n d i c a t e t h a t t h e large p a r t i c l e s s t i c k to t h e

1 ft

o u t e r s u r f a c e o f t h e z e o l i t e c r y s t a l s .

The f i n a l i r o n c o n t e n t o f t h e t h e r m a l l y decomposed F e ( C 0 )5/ F A U - a d d u c t s i s i n

t h e r a n g e b e t w e e n 3 and 6 w t - % o f d r y z e o l i t e , i n d i c a t i n g a t o t a l i r o n l o s s

425

o f a b o u t 5 0 % w i t h r e s p e c t t o t h e o r i g i n a l i r o n c a r b o n y l l o a d i n g ( a f t e r de­

g a s s i n g s a t u r a t e d a d d u c t s a t Τ = 295 Κ, an i r o n l o a d i n g o f c a . 9 w t - % r e -

8 9 m a i n s on FAU ' ) . T h i s r e l a t i v e l y h i g h i r o n c o n t e n t e x c e e d s by f a r t h o s e ob-

17 18 t a i n e d on γ-ΑΙ^Ο^ o r g r a p h i t e .

CONCLUSION

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

i n a q u a r t z r e a c t o r u n d e r f l u i d i z e d s h a l l o w bed c o n d i t i o n s .

M a g n e t i c i s o t h e r m s o f t h e r e s p e c t i v e s a m p l e s t a k e n i n a F o n e r m a g n e t o m e t e r

u n d e r i n e r t c o n d i t i o n s w e r e e v a l u a t e d u s i n g a B r i l l o u i n f i t .

T h e r m a l d e c o m p o s i t i o n o f t h e Fe( C O ) ^ / F A U - a d d u c t i s a c h i e v e d u n d e r vacuum

a l r e a d y a t 370 Κ w i t h l o w h e a t i n g r a t e s , w h e r e a s d e c o m p o s i t i o n u n d e r f a s t

h e a t i n g r a t e s c a n be c o m p l e t e d w i t h i n a f e w m i n u t e s a t c a . 500 K. Low tem­

p e r a t u r e / v a c u u m as w e l l as h i g h t e m p e r a t u r e / i n e r t gas t h e r m o l y s i s g i v e s iron

c l u s t e r s y s t e m s w i t h a t l e a s t 70 - 90 w t - % s m a l l e r t h a n 1 nm, i n d i c a t i n g

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

d i t i o n s .

A d d i t i o n a l c h a r a c t e r i z a t i o n o f t h e g e n e r a t e d i r o n z e o l i t e s by Mb s s b a u e r

19 s p e c t r o s c o p y , EXAFS and c a t a l y t i c t e s t i n g i s u n d e r w a y .

ACKNOWLEDGEMENTS

T h . B. i s i n d e b t e d t o t h e " A l f r i e d K r u p p v on B o h l e n und H a l b a c h - S t i f t u n g "

f o r a g r a n t . P.A. J . a c k n o w l e d g e s a p e r m a n e n t r e s e a r c h p o s i t i o n as " S e n i o r

R e s e a r c h A s s o c i a t e " f r o m N.F.W.O.-F.N.R.S. ( B e l g i u m ) . F i n a n c i a l s u p p o r t

f r o m t h e "Fonds d e r Che m i s c h e n I n d u s t r i e " and t h e " D e u t s c h e F o r s c h u n g s g e ­

m e i n s c h a f t " (DFG) (F.R.G.) i s g r a t e f u l l y a c k n o w l e d g e d .

REFERENCES

1 J.H. S i n f e l t , A d v . C a t a l . 23 ( 1 9 7 3 ) 9 1 .

2 M. B o u d a r t , L.D. P t a k , J . C a t a l . 16 ( 1 9 7 0 ) 9 0 .

3 P.A. J a c o b s i n : C a t a l y s i s by Z e o l i t e s , B. I m e l i k , C. N a c c a c h e , Y. Ben T a a r i t ,

C. V e d r i n e , G. C o u d u r i e r and H. P r a l i a u d , e d s . , E l s e v i e r , A msterdam ( 1 9 8 0 )

2 9 3 .

4 M. B o u d a r t , H. T o p s 0 e , J.A. D u m e s i c , i n : The P h y s i c a l B a s i s f o r H e t e r o g e ­

neous C a t a l y s i s , E. D r a u g l i s , R . I . J a f f e e , e d s . , P l e n u m , New Y o r k ( 1 9 7 4 )

3 3 7 .

426

5 P.A. J a c o b s , D. v a n Wouwe, J . M o l . C a t a l . 17 ( 1 9 8 2 ) 1 4 5 .

6 P.A. J a c o b s , C a t a l . Rev. - S e i . E n g . 24 ( 1 9 8 2 ) 4 1 5 .

7 T h . B e i n , D i s s e r t a t i o n , U n i v e r s i t y o f Hamburg ( 1 9 8 4 ) .

8 T h . B e i n , P.A. J a c o b s , F. S c h m i d t , i n : M e t a l M i c r o s t r u c t u r e s i n Z e o l i t e s ,

P.A. J a c o b s , N . I . J a e g e r , P. J i r u a nd G. S c h u l z - E k l o f f , e d s . , E l s e v i e r ,

A m sterdam ( 1 9 8 2 ) 1 1 1 .

9 T h . B e i n , P.A. J a c o b s , J . C S . F a r a d a y T r a n s . I , 79 ( 1 9 8 3 ) 1 8 1 9 .

10 T h . B e i n , P.A. J a c o b s , J . C S . F a r a d a y T r a n s . I ( 1 9 8 4 ) i n p r e s s .

11 F. S c h m i d t , T h . B e i n , U. O h l e r i c h , P.A. J a c o b s , S i x t h I n t e r n a t i o n a l Z e o l i t e

C o n f e r e n c e , Reno, U.S.A. ( 1 9 8 3 ) , B u t t e r w o r t h , i n p r e s s .

12 W. R o m a n o w s k i , Ζ. a n o r g . a l l g . Chem. 351 ( 1 9 6 7 ) 1 8 0 .

13 F. S c h m i d t , U. S t a p e l , Η. W a l t h e r , B e r . B u n s e n g e s . P h y s . Chem. 88 ( 1 9 8 4 )

3 1 0 .

14 D.M.S. B a g g u l e y , P r o c . Roy. S o c . ( L o n d o n ) A 228 ( 1 9 5 5 ) 5 4 9 .

15 R. van H a r d e v e l d , F. H a r t o g , S u r f a c e S e i . 15 ( 1 9 6 9 ) 1 8 9 .

16 T h . B e i n , P.A. J a c o b s , u n p u b l i s h e d r e s u l t s .

17 A. B r e n n e r , D.A. H u c u l , I n o r g . Chem. 18 ( 1979) 2 8 3 6 .

18 J . P h i l l i p s , B. C l a u s e n , J.A. D u m e s i c , J . P h y s . Chem. 84 ( 1 9 8 0 ) 1 8 1 4 .

19 T h . B e i n , G. S c h m i e s t e r , F. S c h m i d t , W. G u n ß e r , G. K a i n d l , a c c e p t e d f o r

p u b l i c a t i o n a t " 3 r d I n t e r n a t i o n a l Symposium on S m a l l P a r t i c l e s a nd I n ­

o r g a n i c C l u s t e r s " , B e r l i n , J u l y 1 9 8 4 .