Zeolite Synthesis - American Chemical Society

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Chapter 13

Zeolite Synthesis in the Presence of Fluoride Ions A Comparison with Conventional Synthesis Methods

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J. L. Guth, H. Kessler, J. M. Higel, J. M. Lamblin, J. Patarin, A. Seive, J. M. Chezeau, and R. Wey Laboratoire de Matériaux Minéraux, Unité Associée au Centre National de la Recherche Scientifique No. 428, Ecole Nationale Supérieure de Chimie, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France -

-

Replacement of OH by F makes it possible to obtain zeolites in media where pH values can be lowered to acidic ones. Under such conditions MFI-, FER-, MTT-, MTN- and TON-structure type materials could be prepared. This route is especially suited for high-silica materials synthesis, but partial substitution of silicon by Β , Al , Ga , Fe , Ge and Ti has been possible too. The ease of substitution decreases with increasing stability of the corresponding fluorocomplezes in the solution. As the supersaturation of crystallizing species i s lower for fluoride-containing media, the number of phases that could be obtained i s smaller (fewer metastable phases), but crystallization is more regular (formation of large crystals with less defects). The choice of templates i s therefore more critical. The new medium enables the incorporation of elements sparingly soluble in alkaline solutions (e.g., Fe ) or of cations such as NΗ +, Co . Finally the presence of F in the materials leads to catalytic pro­ perties modifications which will be discussed. III

III

III

III

IV

III

IV

2+

4

In a r e c e n t paper ( 1). o u r l a b o r a t o r y reported the hydrothermal s y n t h e s i s o f s i l i o a - r i c h , A l , Β and (Al+B) HFI-type z e o l i t e s i n nona l k a l i n e medium ( 2 - 4 ) . The v e r y pure m a t e r i a l s so o b t a i n e d e x h i b i t a high c r y s t a l l i n i t y and a r e g u l a r morphology which seem t o be rela­ ted t o t h e i r growth i n m o d e r a t e l y s u p e r s a t u r a t e d solutions. Their characterization (5,6) and t h e s t u d y o f t h e i r p r o p e r t i e s ( 7) has d i s c l o s e d d i f f e r e n c e s t o z e o l i t e s o f t h e same s t r u c t u r e and s i m i l a r c o m p o s i t i o n o b t a i n e d i n a l k a l i n e medium. The development o f t h e s y n t h e s i s i n f l u o r i d e medium has been studied i n c o n n e c t i o n w i t h t h e new p o s s i b i l i t i e s opened by t h i s method ( i n c o r p o r a t i o n i n t h e framework o f e l e m e n t s s p a r i n g l y solu­ ble i n a l k a l i n e medium, s y n t h e s i s w i t h o u t alkaline cations, new p o s s i b l i l i t y t o d i r e c t l y i n c o r p o r a t e c a t i o n s such a s N H 4 + , divalent c a t i o n s , t h e good s t a b i l i t y o f u s u a l t e m p l a t e s i n t h i s medium,...).

0097-6156/89/0398-0176$06.00A)

ο 1989 American Chemical Society In Zeolite Synthesis; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

13. GUTH ET AL.

177

Zeolite Synthesis with Fluoride Ions

Synthesis and c h a r a c t e r i z a t i o n has been s p e c i a l l y investigated i n the c a s e o f i ) HFI s t r u c t u r a l t y p e m a t e r i a l s w i t h a p u r e l y s i l i c e o u s framework, or w i t h s i l i c o n p a r t l y s u b s t i t u t e d by t r i v a l e n t ( B , A l , F e , Ga) o r t e t r a v a l e n t (Ge, T i ) elements. i i ) p u r e l y s i l i c e o u s and s i l i c o a l u m i n a t e z e o l i t e s o f t h e s t r u c t u r a l t y p e s FER, TOM, HTT and HTH ( 8 ) .

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EXPERIMENTAL 125 ml P T F B - l i n e d s t e e l a u t o c l a v e s were used. I n o r d e r t o remove any solid which might have been s t u c k on t h e c o a t i n g , a washing w i t h a 50 % HF aqueous s o l u t i o n was performed b e f o r e e v e r y new synthesis. The s o l i d p r o d u c t s were c a r e f u l l y examined under t h e o p t i c a l pola­ r i z i n g m i c r o s c o p e (morphology and s i z e , p r e s e n c e o f amorphous impu­ rities) . I d e n t i f i c a t i o n was t h e n performed u s i n g powder X-ray dif­ f r a c t i o n ( P h i l i p s PR 1130 d i f f r a c t o m e t e r ) ( 1). C a l c i n a t i o n i n o r d e r t o decompose and remove t h e t e m p l a t e was m o n i t o r e d by thermogravimet r y ( M e t t l e r 1 Thermoanalyzer), d i f f e r e n t i a l thermal a n a l y s i s ( S e ­ t a ram M2) o r d i f f e r e n t i a l s c a n n i n g c a l o r i m e t r y (Setaram DSC-111). The c h e m i c a l environment o f atoms i n t h e s o l i d s was s t u d i e d by NMR (MAS and CP-MAS). Resonance o f B , C , F , A l and S i nuclei was r e c o r d e d on a B r u k e r MSL-300 s p e c t r o m e t e r o p e r a t i n g a t a 7 T e s l a magnetic f i e l d . Chemical a n a l y s i s o f s i l i c o n and o f i t s s u b s t i t u e n t s was performed by atomic a b s o r p t i o n s p e c t r o s c o p y a f t e r d i s s o l v i n g t h e material i n HF ( 9). I n some c a s e s , a s p o t a n a l y s i s and X-ray emis­ s i o n mapping o f t h e s e elements i n t h e c r y s t a l s was c a r r i e d o u t on a C a s t a i n g t y p e ( Camebaz) e l e c t r o n microscope. The f l u o r i n e c o n t e n t was determined by n e u t r o n a c t i v a t i o n or, a f t e r dissolution o f t h e s o l i d , by p o t e n t i o m e t r y u s i n g a F"-selective e l e c t r o d e ( 1 0 ) . The c a t a l y t i c a c t i v i t y was e s t i m a t e d w i t h a methanol conversion test a t 370°C and v a r i a b l e H. H. S. V. 1 1

1 3

1 9

2 7

2 9

RESULTS AMD DISCUSSION CRYSTALLIZATION o f ZEOLITES i n OH" o r i n F" MEDIA. Due t o t h e low s o l u b i l i t y o f z e o l i t e s , t h e y i e l d o f c r y s t a l l i z a t i o n i s poor when i t is c a r r i e d o u t from a c l e a r s o l u t i o n . To a v o i d t h i s drawback, t h e s o l u t i o n i s f e d by c o n t i n u o u s l y d i s s o l v i n g a s o l i d which i s m o s t l y an o x i d e o r h y d r o x i d e g e l o f t h e framework-forming elements Τ (11). Silicate, a l u m i n a t e and a l u m i n o s i l i c a t e a n i o n s a r e t h u s formed by s o l u b i l i z a t i o n o f t h e S i and A l s o u r c e s i n t h e p r e s e n c e o f OH". The latter i s t h e m o b i l i z i n g agent used t o t r a n s f e r these elements t h r o u g h t h e s o l u t i o n : i t i s consumed on d i s s o l u t i o n and r e g e n e r a t e d on c r y s t a l l i z a t i o n . I n t h e new r o u t e , t h i s r o l e i s p l a y e d by fluo­ r i d e ( F~) a n i o n s . The c r y s t a l l i z a t i o n becomes t h u s p o s s i b l e i n neu­ t r a l and even i n a c i d i c media. The l i q u i d phase must f u r t h e r c o n t a i n s p e c i e s which w i l l g e n e r a t e t h e m i c r o p o r o u s volume by o c c u p y i n g t h e c a v i t i e s and c h a n n e l s o f t h e framework. These t e m p l a t e s a r e e i t h e r c a t i o n s t o compensate t h e n e g a t i v e c h a r g e s o f t h e framework o r neu­ t r a l s p e c i e s ( i o n p a i r s , m o l e c u l e s ) . Due t o t h e i r i n t e r a c t i o n s , they s t a b i l i z e t h e s t r u c t u r e and make c r y s t a l l i z a t i o n p o s s i b l e . The s y n ­ t h e s i s p r o c e s s c a n be r e p r e s e n t e d as f o l l o w s :

In Zeolite Synthesis; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

178

ZEOLITE SYNTHESIS S o l i d r e a c t a n t s source ( m o s t l y amorphous) •OH"

dissolution

Solution containing species f o r - framework b u i l d i n g - micropore f i l l i n g

e. g., s i l i c a t e s e. g., a l unifiâtes

e. g., f l u o s i l i c a t e s e. g., f l u o a l u m i n a t e s

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polycondensation crystalline zeolite The zeolites

OH~and F~ s y n t h e s i s media a r e compared i n T a b l e I and t h e o b t a i n e d so f a r i n F~ media a r e l i s t e d i n t a b l e I I .

T a b l e I. Comparison o f t h e OH" and F~ r e a c t i o n media used i n z e o l i t e s y n t h e s i s

F~ medium

0H~ medium PH Hobilizing agents

> 10 = (1-11) OH" F" Bases: NaOH, Pr 0H,. . . A c i d s : HF,. . . Salts: Ν β σ θ . . . S a l t s : HH F,. .. M o l e c u l e s : amines,... Molecules: B F 3 , Oxides, h y d r o x i d e s , a l k o x i d e s , s a l t s (amorphous o r c r y s t a l l i n e s o l i d s ) I o n i c compounds ( s a l t s , bases) : P^NBr,. . . M o l e c u l e s : P r 3 N,. . . > 20° > 40° From a few hours t o s e v e r a l days 4

2

Τ element sources Template Temperature Duration

Table II. Z e o l i t e s

3 >

4

o b t a i n e d so f a r i n F" media

S t r u c t u r e type

MFI

FER

TOM

Τ elements

Si Si+Be, B, A l , Ga, Fe, Ge, T i

Si* Si+Al, Fe

Si Si+Al*

* difficult

MTT Si Si+Al*

Si+Al

t o s y n t h e s i z e ; ** non r e p r o d u c i b l e s y n t h e s i s .

In Zeolite Synthesis; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

Si+Al

13. GUTHETAL.

179

Zeolite Synthesis with Fluoride Ions

HFI-type ZEOLITES. A large number o f MFI-type z e o l i t e s c o u l d be obtained i n F~ media (2-4. 12-15) a c c o r d i n g t o t h e d e s c r i b e d route ( 1) w i t h P r H H ( 4 _ ) ( P r = η-propyl, χ = 1 t o 4) t e m p l a t e s and f o r the Τ elements quoted above. P ^ N * i s t h e b e s t t e m p l a t e ( T a b l e I I I ) . +

x

X

+

Table III.

T e m p l a t i n g e f f i c i e n c y o f P r N H ( 4_ ) i n t h e absence and i n t h e presence of A l s u b s t i t u t i n g f o r S i x

+

Pr H Pr MH Pr MH2 PrNH * 4

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+

3

+

2

3

(

X

Τ = Si

Τ = Si, Al

MFI HFI MTT ( HFI) HTH (FER) (HFI)

HFI HFI HFI (HTT) FER (HFI)

) g e n e r a l l y as a s e c o n d a r y phase.

C r y s t a l s a r e always o f good q u a l i t y and t h e s i z e exceeds gene­ rally the values observed i n a l k a l i n e - t y p e s y n t h e s i s . A d d i t i o n of seeds d e c r e a s e s t h e c r y s t a l l i z a t i o n time and a l l o w s t a i l o r i n g o f t h e size. The morphology i s t h e same as f o r c r y s t a l s o b t a i n e d by t h e u s u a l a l k a l i n e r o u t e . The l e n g t h / w i d t h r a t i o d e c r e a s e s w i t h χ i n t h e t e m p l a t e and t h e s u b s t i t u t i o n degree o f S i ( 1 6 ) . The s u b s t i t u t i o n by t r i v a l e n t elements leads g e n e r a l l y t o c r y s t a l s with l e s s f l a t faces which i n d i c a t e s t h a t c r y s t a l l i z a t i o n o c c u r e d i n a more super-satu­ r a t e d medium. PURELY SILICEOUS HFI-tvpe ZEOLITES. Among t h e t e m p l a t i n g cations which were used, P r N proved t o be t h e most e f f i c i e n t f o r easy and fast crystallization. I n T a b l e IV a r e g i v e n the c r y s t a l l o g r a p h i c c h a r a c t e r i s t i c s o f t h e o b t a i n e d s i l i c e o u s HFI-type z e o l i t e s (16) as a f u n c t i o n o f t h e template. +

4

T a b l e IV. U n i t c e l l f o r m u l a and c r y s t a l p a r a m e t e r s of t h e s i l i c e o u s HFI-type z e o l i t e s ( a s s y n t h e s i z e d and (*) c a l c i n e d )

unit c e l l JSi

9 6

0

1 9 2

formula

a (A)

| 4Pr KF

b ( A)

c ( Α)

20.039(3) 19.928(3) 13.382(3)

4

I 96°19214Pr NHF Si

20.048( 2) 19.889( 2) 13.383(3)

3

β (°) 90 90

vol. ( A )

3

5344(3) 5337( 3)

8H 0 2

|Si

9 6

0

1 9

2 | 4 . 8 P r M H F 20.045( 4) 19.886(3) 13.379(5) 2

6. 5H 0 *Si 0 2

2

90

5334(3)

2

9 6

1 9

13.383(5) 20.107(4) 19.887(3)

90.63(3) 5351(3)

In Zeolite Synthesis; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

180

ZEOLITE SYNTHESIS

R a t e r m o l e c u l e s occupy the volume o f t h e c h a n n e l s which i s l e f t emp­ ty by t h e t e m p l a t e s c a r r y i n g l e s s t h a n f o u r p r o p y l groups. The cat i o n i c n a t u r e o f t h e t e m p l a t e s was e s t a b l i s h e d by C NMR. Rhereas P^N* o c c u p i e s t h e s t r a i g h t and z i g z a g c h a n n e l s ( 17) « the Pr3ifH and P r N H 2 c a t i o n s are l o c a t e d p r e f e r e n t i a l l y i n t h e z i g z a g chan­ nels. Such a c o n c l u s i o n c o u l d be drawn from the f o l l o w i n g observa­ t i o n s (16) : i) b ( p a r a l l e l t o the s t r a i g h t c h a n n e l s ) d e c r e a s e s , a increases and c s t a y s c o n s t a n t on g o i n g from P ^ N * to Pr NH2 . i i ) The P^NH* and Pr2NH2 s p e c i e s decompose a c c o r d i n g t o DSC under argon a t about t h e same temperature (535 and 515°C). Such a tempera­ ture i s much h i g h e r t h a n t h e d e c o m p o s i t i o n temperature of Pr NH2 occluded i n t h e MTT s t r u c t u r e ( 5

2 >5

0 0

2 #5

7 1

7

7 1β 7

F . ] 1. 4PrNH F 1. 5H 0 F . ] 18H 0. 0

3

0

3

3

2

2

I t may t h e n be c o n c l u d e d t h a t 12 % o f t h e n e g a t i v e c h a r g e s i n ­ by A l a r e not r e v e a l e d owing t o t h e p r e s e n c e o f F ( 20). The e f f e c t o f t h e a d d i t i o n o f F t o t h e s t a r t i n g m i x t u r e on t h e adsorption and t h e c a t a l y t i c p r o p e r t i e s i s q u i t e significant. For example, t h e h y d r o p h o b i c i t y o f p u r e l y s i l i c e o u s samples i s c o n s i d e ­ rably enhanced ( l e s s Si-OH g r o u p s ) . F i g u r e 6 shows t h a t such a ma­ terial adsorbs more n-propanol from a d i l u t e n-propanol + water s o l u t i o n t h a n a m a t e r i a l which was p r e p a r e d i n a l k a l i n e medium. The complete o r p a r t i a l c a n c e l l i n g by F o f t h e n e g a t i v e c h a r g e s i n d u c e d by t h e i n c o r p o r a t i o n o f t r i v a l e n t elements such as A l i n f l u duced

In Zeolite Synthesis; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

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13.

GUTHETAK

Zeolite Synthesis with Fluoride Ions

189

A T O N 5 0 ° / . T O N 50·/.

2 0 d a y s (static) FERIOO'/.FERIOOV.FER+TON

T O N 20'/.

10 'FER

90V.

7

30

50

35

300

Si/AI(starting) •TON 100V.

• F E R 60*/.

T O N 100V.

10 d a y s ( a g i t a t e d )

T O N 95V.

(•in p r e s e n c e of s e e d s )

Ψ F i g u r e 4 : I n f l u e n c e of s t a r t i n g seeding on FER- and TON-type n - b u t y l a m i n e template.

S i / A l r a t i o , time, a g i t a t i o n and materials crystallization with

In Zeolite Synthesis; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

ZEOLITE SYNTHESIS

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190

F i g u r e 5. S c a n n i n g e l e c t r o n m i c r o g r a p h s o f (a) FER-, and (c) MTT-type m a t e r i a l s . C o n t i n u e d on next page.

(b)

In Zeolite Synthesis; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

TON-,

GUTHETAL.

191

Zeolite Synthesis with Fluoride Ions

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13.

Figure 5. Continued. Scanning electron micrographs of (d) (e) NUl-type materials, and (f) of a novel c l a t h r a s i l .

In Zeolite Synthesis; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

MTN-,

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192

ZEOLITE SYNTHESIS

F i g u r e 6 : n - p r o p a n o l a d s o r p t i o n ( from d i l u t e aqueous n-propanol solutions) o f HFI-type z e o l i t e s p r e p a r e d (a) i n a l k a l i n e medium and ( b) i n f l u o r i d e medium .

In Zeolite Synthesis; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

13. GUTHETAK

193

Zeolite Synthesis with Fluoride Ions

ences t h e a c i d c a t a l y s i s p r o p e r t i e s . I t was found, f o r example, t h a t methanol t o h y d r o c a r b o n c o n v e r s i o n was v e r y low on t h e above-men­ tioned Mg-MFI sample c o n t a i n i n g 3. 3 A l and 3 F p e r u n i t c e l l . The conversion reached however 100 % on t h e d e f l u o r i n a t e d r e c a l c i n e d sample. A FER-type sample which was p r e p a r e d by u s i n g conditions close t o t h e c o n d i t i o n s employed f o r t h e above FER-type sample (2.5A1 and 0. 3F p e r u n i t c e l l ) but c o n t a i n i n g C o + i n s t e a d o f Hg , showed a methanol c o n v e r s i o n y i e l d o f about 100 %, which d e c r e a s e d slowly w i t h i n c r e a s i n g time-on-stream (90 % c o n v e r s i o n after 26h, H. H. S. V. » 0 . 4 ) . The a c t i v i t y o f t h e same sample which was f i r s t defluorinated and r e c a l c i n e d , d e c r e a s e d more r a p i d l y owing t o s t r o n g and r a p i d c o k i n g on t h e a c i d s i t e s which were a v a i l a b l e from t h e outset. In c o n t r a s t , i n the case of the n o n - d e f l u o r i n a t e d sample, the f o r m a t i o n o f water d u r i n g t h e c o n v e r s i o n l e a d s t o t h e gradual e l i m i n a t i o n o f F and t h u s makes t h e a c i d s i t e s s l o w l y a v a i l a b l e .

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2

2 +

CONCLUSIONS By using f l u o r i d e anions i n z e o l i t e synthesis, i t i s p o s s i b l e t o e x t e n d t h e u s u a l a l k a l i n e pH range t o a n e u t r a l o r a c i d i c one. The r e p l a c e m e n t o f OH" by F" f o r t h e f o r m a t i o n o f s o l u b l e fra­ mework b u i l d i n g s p e c i e s f a c i l i t a t e s the i n c o r p o r a t i o n of Τ elements which are s p a r i n g l y s o l u b l e (e.g., F e , T i ) o r do n o t polycondensate e a s i l y ( e . g . , G e ) i n a l k a l i n e medium. The n a t u r e of the soluble species i s s t i l l n o t w e l l known, i . e . , c o o r d i n a t i o n and type o f t h e o t h e r l i g a n d s b e s i d e F~( e. g., H 0, OH). Particularly, the F/( o t h e r l i g a n d s ) r a t i o seems t o be c r i t i c a l . A compromise has to be found, a low f l u o r i d e c o n t e n t h i n d e r s s o l u b i l i z a t i o n and a high content p r e v e n t s p o l y c o n d e n s a t i o n . The compromise leads to systems which a r e l e s s s u p e r s a t u r a t e d t h a n f o r a l k a l i n e media. Hen­ ce, f e w e r m e t a s t a b l e phases a r e o b t a i n e d . T h i s i s however also an advantage s i n c e b e t t e r c o n t r o l l e d n u c l e a t i o n and s l o w e r growth rate yield crystals w i t h fewer d e f e c t s and w i t h controlled size. The relative stability of the fluoro-complexes o f the elements which were studied, i s strongly i n favour of s i l i c o n incorporation. This F~ route i s therefore well s u i t e d f o r obtaining s i l i c a - r i c h mater­ i a l s , i . e., o f t h e p e n t a s i l type. But t h e s m a l l number o f framework negative c h a r g e s l e a d s t o fewer t e m p l a t i n g c a t i o n - f r a m e w o r k inter­ actions. This, and t h e l o w e r s u p e r s a t u r a t i o n , make t h e s y n t h e s i s more c r i t i c a l and enhance the r o l e of the template f o r the s t a b i l i ­ z a t i o n o f t h e z e o l i t e s t u c t u r e . C h o i c e o f t h e t e m p l a t e becomes thus more c r i t i c a l . A good s t e r i c and c h e m i c a l f i t t o t h e framework has to be r e a c h e d i n o r d e r t o i n c r e a s e t h e f a v o u r a b l e i n t e r a c t i o n s and also t h o s e between t h e s p e c i e s which a r e p r e s e n t i n t h e pores. It should be mentioned f u r t h e r t h a t many o r g a n i c s p e c i e s such as t h e q u a t e r n a r y ammonium i o n s a r e more s t a b l e i n a n e u t r a l medium t h a n i n an a l k a l i n e one. Neutral or a c i d i c pH v a l u e s make i t p o s s i b l e t o s t a r t w i t h c a ­ t i o n s which a r e s p a r i n g l y s o l u b l e i n a l k a l i n e medium ( e . g . divalent c a t i o n s ) o r do n o t e x i s t i n s u c h a medium ( e. g. N H 4 ) . Hhen t h e NH4' ' c a t i o n s r e p l a c e the usual a l k a l i cations, the m a t e r i a l s obtained are therefore alkali-free and a s i m p l e c a l c i n a t i o n y i e l d s the a c i d i c form o f t h e z e o l i t e . The c a t i o n exchange s t e p i s t h u s bypassed. 1 1 1

I V

I V

2

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Finally a m o d i f i c a t i o n o f exchange, a d s o r p t i o n and catalytic p r o p e r t i e s has been found (e. g., i n c r e a s e d h y d o p h o b i c i t y , cancelling of framework c h a r g e s ) . He thank Dr Ζ. GABELICA from Namur u n i v e r s i t y f o r h i s c o n t r i b u ­ t i o n t o t h e s t u d y o f t h e germanium i n c o r p o r a t i o n and Miss A. C. FAUST f o r t h e s y n t h e s i s and t h e a n a l y s i s o f many samples.

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LITERATURE CITED

1. J. L. Guth, H. Kessler, R. Wey, in "New Developments in Zeolite Science and Technology, Proceedings of the 7th Int. Zeolite Conf.". Ed. Y. Murakami, A. Iijima, J. W. Ward, Tokyo 1986, Kodensha-Elsevier, p. 121. 2. J. L. Guth, H. Kessler, M. Bourgogne, R. Wey, G. Szabo, Fr. Pat. Appl. 84-07773, 1984. 3. J. L. Guth, H. Kessler, M. Bourgogne, R. Wey, G. Szabo, Fr. Pat. Appl. 84-11521, 1984. 4. J. L. Guth, H. Kessler, R. Wey, A. C. Faust, Fr. Pat. Appl. 8507978, 1985. 5. H. Kessler, J. M. Chezeau, J. L. Guth, G. Coudurier, H. Strub, Zeolites, 1987, 7(4) 360-366. 6. M. Soulard, S. Bilger, H. Kessler, J. L. Guth, Zeolites, 1987, 7 (5) 463-70. 7. F. Raatz, unpublished results. 8.W.M. MEIER, D. H. OLSON, Atlas of Zeolite Structure Types, 1987, Butterworth. 9. L. Delmotte, Thesis, UHA Mulhouse, 1985. 10. J. L. Guth, R. Wey, Bull. Soc. Fr. Minéralogie et Cristallographie, 92 105-107, 1969. 11. J. L. Guth, P. Caullet, J. Chimie Physique, 1986, 83(3) 155-175. 12. J. Patarin, J. L. Guth, H. Kessler, G. Coudurier, F. Raatz, Fr. Pat. Appl. 86-17711, 1986. 13. J. L. Guth, H. Kessler, J. M. Popa, Fr. Pat. Appl. 87-07187, 1987. 14. Z. Gabelica, J. L. Guth, Fr. Pat. Appl. 88-04367, 1988. 15. A. Seive, J. L. Guth, F. Raatz, L. Petit, Fr. Pat. Appl. 88-06509, 1988. 16. J. Patarin, Thesis, UHA Mulhouse, 1988 ; J. Patarin, M. Soulard, H. Kessler, J. L. Guth, J. Baron, Zeolites (accepted). 17. G. D. Price, J. J. Pluth, J. V. Smith, J. M. Bennet, R. L. Patton, J. A. C.S.,1982, 104 5971-77. 18. A. M. Bond, G. T. Hefter, "Critical survey of stability constants and related thermodynamic data of fluoride complexes in aqueous solutions" Ed. IUPAC, 1980, Pergamon Press. 19. J. Patarin in "Précurseurs moléculaires de matériaux inorganiques - Ecole d' été, Procédés Sol-Gel" Carcans Maubuisson, France, 1987. 20. J. M. Higel, Thesis, UHA Mulhouse , 1987. 21. J. A. Rossin, C. Saldarriaga, M. E. Davis, Zeolites, 1987, 7(4) 295-300. 22. D. G. Hay, H. Jaeger, J. C. S., Chem. Com., 1984, 1433-35. 23. J. L. Guth, A. C. Faust, F. Raatz, J. M. Lamblin, Fr. Pat. Appl. 86-16362, 1986.

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24. J. Patarin, J. M. Lamblin, A. C. Faust, J. L. Guth, F. Raatz, Fr. Pat. Appl. 88-06841, 1988. 25. J. Patarin, J. L. Lamblin, A. C. Faust, J. L. Guth, F. Raatz, Fr. Pat. Appl. 88-08105, 1988. 26. E. W. Valyocsik, L. D. Rollmann, Zeolites, 1985, 5, 123-125. 27. P. A. Jacobs, J. A. Martens, "Synthesis of high-silica aluminosilicate zeolites", Studies in Surface Science and Catalysis, 1987, Vol. 33, Elsevier, p. 330 and p. 361. 28. D. W. Breck "Zeolite Molecular Sieves. Structure Chemistry and Use", 1974, John Wiley and Sons., p. 272. 29. L. Petit, J. L. Guth, H. Kessler, F. Raatz, Réunion du Groupe Français des Zéolithes, Eveuz, 1988 (Poster).

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RECEIVED December 22, 1988

In Zeolite Synthesis; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.