Novel Materials in Heterogeneous Catalysis - American Chemical

Chapter 2

Templates in the Transformation of Zeolites to Organozeolites Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on April 29, 2016 | http://pubs.acs.org Publication Date: September 21, 1990 | doi: 10.1021/bk-1990-0437.ch002

Cubic Ρ Conversions Stacy I. Zones and Robert A. Van Nordstrand Chevron Research Company, 576 Standard Avenue, Richmond, CA 94802-0627

This study concerns the conversion of Cubic Ρ zeolite to organozeolites as influenced by a variety of quaternary ammonium templates. In general, when t r i methyl ammonium is attached to a cyclohexane, or more elaborated cyclic or polycyclic structure, high silica zeolites composed of four- and six-ring s i l i cate subunits are produced. Conversion rates are proportional to organocation size with adamantane the fastest and cyclohexane the slowest. With symmetric tetraalkyl ammonium or linear diquaternary ammonium templates, organozeolites with predominantly five -ring subunits are produced instead. In one instance, a linear diquat gave no conversion of Ρ and demon strated an inhibitory effect when a subsequent tem plate was introduced into the reaction. T h i s paper p r e s e n t s r e s u l t s o f a c o n t i n u a t i o n o f o u r study (1,2) o f the c o n v e r s i o n o f t h e s m a l l - p o r e z e o l i t e , Cubic P, i n t o v a r i o u s o r g a n o z e o l i t e s — l a r g e - , medium-, and s m a l l - p o r e v a r i e t i e s . The main f o c u s h e r e i s on t h e i n f l u e n c e o f s t r u c t u r e o f t h e q u a t e r n a r y amine t e m p l a t e m o l e c u l e on the r a t e s o f c o n v e r s i o n and on t h e o r g a n o z e o l i t e produced. R e c e n t l y , we d e s c r i b e d t h e s y n t h e s i s o f an a l l - s i l i c a m o l e c u l a r s i e v e , SSZ-24 ( i s o s t r u c t u r a l w i t h AlPO-5) composed o f f o u r - and s i x r i n g s i l i c a t e s u b u n i t s (_3_) · T h i s r e s u l t was unexpected because most h i g h s i l i c a s y n t h e s e s produce s t r u c t u r e s r i c h i n f i v e r i n g s (pentasils). This new s i e v e i s produced i n a r e a c t i o n u s i n g Ν,Ν,Ν-trimethyladamantammonium c a t i o n . T h i s same c a t i o n can, under d i f f e r e n t s y n t h e s i s c o n d i t i o n s , produce a h i g h s i l i c a form o f chabaz i t e , SSZ-13 ( 4 , 5 ) . And, a g a i n , t h i s s t r u c t u r e i s d e v o i d o f f i v e rings. However, u s i n g t h e s i m p l e adamantane amine, c l a t h r a t e s i l i c a t e s a r e produced, mostly f i v e - r i n g s t r u c t u r e s (6-8). This r a i s e s q u e s t i o n s about how t h e t e m p l a t e , t h e s i l i c a - a l u m i n a r a t i o , and

0097-6156/90/0437-0014$06.00/0 © 1990 American Chemical Society Baker and Murrell; Novel Materials in Heterogeneous Catalysis ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

2. ZONES AND VAN NORDSTRAND

Templates in Transformation of Zeolites 15

other f a c t o r s c o n t r o l the features o f c r y s t a l s t r u c t u r e . Studies by S i NMR {9) have shown t h e s i l i c a t e s o l u t i o n s have such a m u l t i t u d e of s i l i c a forms t h a t i t i s n o t c l e a r how c r y s t a l s t r u c t u r e c o n t r o l i s achieved. We have found a z e o l i t e s y n t h e s i s r e a c t i o n which i s a t t h e boundary between t h e f i v e - r i n g s t r u c t u r e and t h e f o u r - and s i x - r i n g s t r u c t u r e p r o d u c t i o n . The p r o d u c t depends on the o r g a n o c a t i o n used. A second f e a t u r e o f t h i s s y n t h e s i s r e a c t i o n i s t h a t no amor phous s o l i d i s i n v o l v e d o r p r o d u c e d . This reaction derives s i l i c a and a l l o f i t s alumina from t h e low s i l i c a z e o l i t e , C u b i c P. T h i s z e o l i t e , o r g a n i c - f r e e , had been e n c o u n t e r e d a s a t r a n s i e n t phase i n the d i s c o v e r y o f SSZ-13 .

Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on April 29, 2016 | http://pubs.acs.org Publication Date: September 21, 1990 | doi: 10.1021/bk-1990-0437.ch002

2 9

+

Templates r e p r e s e n t e d b y the f o r m u l a Me N R have been used i n t h i s work t o s t u d y the i n f l u e n c e o f t h e R group, which i s r e f e r r e d to as t h e n o n p o l a r end o f the c a t i o n . More complex c a t i o n s have been used s h e d d i n g some l i g h t on t h e i n f l u e n c e o f the p o l a r e n d . One c a t i o n examined was n o t e f f e c t i v e i n c o n v e r t i n g t h e C u b i c Ρ b u t was e f f e c t i v e i n b l o c k i n g t h e s u r f a c e o f t h e C u b i c Ρ s o t h a t o t h e r t e m p l a t e s were i n e f f e c t i v e . The s t u d y opens q u e s t i o n s r e g a r d i n g how the p o l a r and the n o n p o l a r ends i n t e r a c t w i t h C u b i c Ρ and how t h e y r e l a t e t o t h e s y n t h e s i s o f SSZ-13 and o t h e r z e o l i t e s ( i n c l u d i n g void-filling)· 3

Experimental The c o n v e r s i o n o f C u b i c Ρ t o o r g a n o z e o l i t e s i s o b s e r v e d b y f o l l o w i n g the r i s e i n pH (measured a t room temperature) ( J ) · X-ray d i f f r a c t i o n was used t o measure e x t e n t o f c o n v e r s i o n . Z e o l i t e s y n t h e s i s r e a c t i o n s were c a r r i e d o u t a t 135°C w i t h 30 rpm t u m b l i n g i n P a r r 4745 r e a c t o r s w i t h T e f l o n c u p s . Unless otherwise stated, the s y n t h e s i s mix c o n s i s t e d o f 0.50 g C u b i c P, 2.5 m i l l i m o l s q u a t e r n a r y ammonium h a l i d e , 5.0 g Banco "N" s i l i c a t e s o l u t i o n (38.5% s o l i d s , S i 0 / N a 0 = 3.22), and 12 mL w a t e r . C u b i c Ρ was p r e p a r e d by r e a c t i n g "N" s i l i c a t e , water, A 1 ( S 0 ) , 18H 0, and NaOH a t 140°C f o r s i x days u n s t i r r e d . The r e s u l t a n t C u b i c Ρ h a s SiC>2/Al2 3 6. 2

2

2

4

3

2

0

Mix f o r Cubic Ρ Synthesis Al/Si Na/Si OH/Si N+/Si H 0/Si 2

0.06 1.05 0.95 0.00 32

=

For Subsequent Synthesis 0.06 0.72 0.65 0.10 32

O r g a n i c s y n t h e s e s were performed b y q u a t e r n i z a t i o n o f amines a c c o r d i n g t o a new p e p t i d e p r o c e d u r e ( 1 0 ) . In some i n s t a n c e s , t h e amine was n o t a v a i l a b l e b u t the d i m e t h y l amino d e r i v a t i v e c o u l d be produced from t h e c y c l i c c a r b o n y l u s i n g t h e L e u k h a r t r e a c t i o n (11)·

Baker and Murrell; Novel Materials in Heterogeneous Catalysis ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

16

NOVEL MATERIALS IN HETEROGENEOUS CATALYSIS

The d i m e t h y l amine d e r i v a t i v e produced was q u a t e r n i z e d d i r e c t l y b y m e t h y l i o d i d e , added s l o w l y t o a c h i l l e d s o l u t i o n o f the t e r n a r y amine i n e t h y l a c e t a t e . When o t h e r r i n g s u b s t i t u e n t s a r e p r e s e n t , the r e d u c t i v e a m i n a t i o n l e a d s t o i s o m e r i c c o n f i g u r a t i o n s , as noted i n T a b l e I . ÇXiaternary ammonium h a l i d e s a l t s were c h a r a c t e r i z e d b y m e l t i n g p o i n t , TLC, or m i c r o a n a l y t i c a l d a t a and H and C NMR. ESCA a n a l y s e s were performed on an HP 5950-A i n s t r u m e n t . E l e m e n t a l c o m p o s i t i o n s were d e t e r m i n e d u s i n g ICP. SEM photos were o b t a i n e d on a H i t a c h i S-570.


1

1 3

Results Rates o f C o n v e r s i o n o f Ρ t o SSZ-13. T a b l e I i s a l i s t o f q u a t e r n a r y ammonium i o d i d e s used i n t h i s s t u d y t o g e t h e r w i t h t h e i r a b b r e v i a t i o n s used h e r e and t h e i r c a r b o n - t o - n i t r o g e n r a t i o s . These tem p l a t e s a l l may be viewed as d e r i v a t i v e s o f Me N+-cyclohexane b y f u r t h e r e l a b o r a t i o n of the cyclohexane r i n g . (The s a l t o b t a i n e d from c i s - m y r t a n y l amine a c t u a l l y c o n t a i n s a methylene b r i d g e from the c y c l o h e x y l r i n g t o t h e charged n i t r o g e n . T h i s s a l t does n o t l e a d t o SSZ-13 b u t c o n v e r t s t h e Ρ v e r y s l o w l y t o m o r d e n i t e . This t e m p l a t e w i l l n o t be c o n s i d e r e d f u r t h e r . ) 3

A comparison o f s y n t h e s i s o f the c o n v e n t i o n a l s o r t , p r o c e e d i n g v i a a s i l i c a - a l u m i n a g e l i n t e r m e d i a t e , and the s y n t h e s i s used h e r e s t a r t i n g w i t h C u b i c Ρ z e o l i t e , i s shown i n F i g u r e 1. The s y n t h e s i s w i t h C u b i c Ρ i s a t l e a s t f i v e times as f a s t as t h e c o n v e n t i o n a l synthesis. The template used was 1-Ada. The v a r y i n g r a t e s o f c o n v e r s i o n o f C u b i c Ρ t o the o r g a n o z e o l i t e SSZ-13 a r e shown i n F i g u r e 2. The d a t a show t h a t t h e l a r g e adaman tane d e r i v a t i v e s produced the most r a p i d c o n v e r s i o n o f Ρ t o SSZ-13, 1-Ada b e i n g more r a p i d than 2-Ada. (The 2-Ada d e r i v a t i v e i s " s a l t e d o u t " o f s o l u t i o n t o a g r e a t e r e x t e n t than t h e 1-Ada. T h i s may a c c o u n t f o r the slower r a t e by 2-Ada. Ihe 9-Non template a l s o has t h i s " s a l t i n g o u t " tendency.) The r a t e s f o l l o w r o u g h l y i n o r d e r o f C/N+ r a t i o , t h e c y c l o C template showing the s l o w e s t r a t e . The adamantane d e r i v a t i v e s f i l l t h e c h a b a z i t e c a v i t y most com p l e t e l y , even t o the p o i n t o f some l a t t i c e d i s t o r t i o n ( J J · Other f a c t o r s f a v o r i n g t h e adamantanes i n c l u d e t h e h i g h C/N+ w i t h c o n s e q u e n t h i g h h y d r o p h o b i c i t y and r i g i d i t y . An i n t e r e s t i n g comparison i s t h a t o f t h e norbornane t e m p l a t e s and t h e 3 Me c y c l o C^. These a l l have t h e same C/N+, b u t t h e c o n v e r s i o n r a t e s f o r the n o r b o r n a n e s were f a s t e r and t h e c o n v e r s i o n was more s e l e c t i v e . The p r o d u c t from the 3 Me c y c l o C^ c o n v e r s i o n c o n t a i n e d some m o r d e n i t e . F i g u r e 3 shows the change o f pH w i t h time f o r the same tem plates. The r e l a t i v e r a t e s a r e s i m i l a r . The r i s e i n pH i s due t o r e l e a s e o f NaOH from the b u f f e r , sodium s i l i c a t e , as t h e s i l i c a i s i n c o r p o r a t e d i n t o the o r g a n o z e o l i t e . 6

The S i 0 / A l 0 v a l u e s o f t h e SSZ-13 p r o d u c e d were i n t h e range 11 t o 13. Na/Al v a l u e s o f the s o l i d p r o d u c t s dropped from 1.00 ( f o r P) t o 0.50 ( f o r SSZ-13). C o n v e r s i o n t o SSZ-13 a s measured by XRD i s p r o p o r t i o n a l t o the n i t r o g e n c o n t e n t o f the s o l i d p r o d u c t , as shown i n F i g u r e 4. Data i n t h i s f i g u r e a r e from v a r i o u s times f o r each o f the t e m p l a t e s i n t h i s s t u d y . The same c a t i o n p o p u l a t i o n i s i n t h e SSZ-13, r e g a r d l e s s o f t h e template u s e d . 2

2

3


2. ZONES AND VAN NORDSTRAND Table

I.

Templates in Transformation of Zeolites

Q u a t e r n a r y Ammonium I o d i d e s Used i n the C o n v e r s i o n o f C u b i c Ρ t o SSZ-13 R - N ( C H o K I " S t r u c t u r e s +

Conformational Isomers

C/N+

Abbreviation i n T h i s Work


R Group and S u b s t i t u t i o n Position

Cis

Myrt.


17


18


Time in Hours at 135°C F i g u r e 1. C r y s t a l l i z a t i o n p r o f i l e f o r SSZ-13 s y n t h e s i s from C u b i c Ρ z e o l i t e and from c o n v e n t i o n a l a l u m i n o s i l i c a t e h y d r o g e l .


ZONES AND VAN NORDSTRAND


1&50

Templates in Transformation of Zeolites

r

Time in Hours at135°C F i g u r e 3. pH change v e r s u s r e a c t i o n time f o r t h e c r y s t a l l i z a t i o n o f SSZ-13 from C u b i c Ρ z e o l i t e i n the o f v a r i o u s organocations·

presence

F i g u r e 4. % c r y s t a l l i n e SSZ-13 v e r s u s n i t r o g e n c o n t e n t i n z e o l i t e product. Data o b t a i n e d f o r c o n v e r s i o n o f C u b i c Ρ z e o l i t e using a variety of organocations.



20


C o n v e r s i o n t o Other Z e o l i t e s . A key q u e s t i o n regards the s i g n i f i cance o f t h e trimethylammonium group on t h e template f o r t h e c o n v e r s i o n o f C u b i c P. T a b l e I I c o n t a i n s t h e t e m p l a t e s s t u d i e d i n t h i s connection. TMA causes c o n v e r s i o n t o t h e o r g a n o z e o l i t e s o d a l i t e and a t a r a t e comparable t o most o f t h e c o n v e r s i o n s t o SSZ-13 shown i n F i g u r e 2. The r a t e s f o r t h i s second p o r t i o n o f t h e s t u d y a r e shown i n F i g u r e 5, based on pH measurements. P r o d u c t s i n t h i s p o r t i o n a r e g e n e r a l l y of the p e n t a s i l c l a s s . Rates o f t h e t e m p l a t e s o t h e r t h a n TMA and TEA were r e l a t i v e l y slow. TEA produced m o s t l y m o r d e n i t e plus a l i t t l e beta. D i q u a t 6 produced m o r d e n i t e , b u t a t a slow r a t e i n s p i t e o f h a v i n g trimethylammonium g r o u p s . In c o n v e n t i o n a l s y n t h e s i s and a t A l / S i o f 0.02 t o 0.07, D i q u a t 6 i s q u i t e e f f i c i e n t i n p r o d u c i n g EU-1 ( 1 2 ) ; b u t i n t h e p r e s e n t s y n t h e s i s s t a r t i n g w i t h C u b i c P, t h e c o n v e r s i o n was slow and no EU-1 was made. ZSM-5 F o r m a t i o n . In e a r l i e r work ( J j , i t was found t h a t w i t h lower c o n c e n t r a t i o n s o f TPA, C u b i c Ρ was n o t c o n v e r t e d t o o t h e r z e o l i t e s over s e v e r a l d a y s . However, when TPA was used a t h i g h e r c o n c e n t r a t i o n s o f t h i s s t u d y , s l o w p r o d u c t i o n o f ZSM-5 was o b s e r v e d . SEM photos o f t h e p r o d u c t showed l a r g e c r y s t a l s o f ZSM-5 and s m a l l a g g r e g a t e s o f C u b i c P. When t h e s e two t y p e s o f c r y s t a l s were s e p a r a t e d b y s e d i m e n t a t i o n from an u l t r a s o n i c b a t h , t h e e l e c t r o n m i c r o p r o b e showed t h e ZSM-5 was o n l y s l i g h t l y e n r i c h e d i n s i l i c a . The slow c o n v e r s i o n o f C u b i c Ρ b r o u g h t about by TPA may be a t t r i b u t e d t o the g r e a t e r s h i e l d i n g o f the charged n i t r o g e n by the p r o p y l group compared t o t h e m e t h y l and e t h y l g r o u p s . Inhibition. D i q u a t 4 produced no change i n C u b i c Ρ d u r i n g s e v e r a l days a t 135°C, and t h e pH d i d n o t r i s e above t h e i n i t i a l v a l u e . E x a m i n a t i o n o f t h i s Ρ sample b y ESCA showed c o n s i d e r a b l e i o n exchange had o c c u r r e d , t h e sodium b e i n g r e p l a c e d by n i t r o g e n . The C u b i c Ρ from a TPA c o n v e r s i o n e x p e r i m e n t showed much l e s s i o n exchange· An e x p e r i m e n t was conducted which showed t h a t D i q u a t 4 e f f e c t i v e l y b l o c k e d t h e s u r f a c e o f C u b i c P, p r e v e n t i n g i t s c o n v e r s i o n b y a normally e f f e c t i v e template. A c o r r e s p o n d i n g e x p e r i m e n t showed t h a t TPA d i d n o t b l o c k t h e s u r f a c e . The C u b i c Ρ was h e a t e d a t 100°C f o r s e v e r a l days w i t h e i t h e r D i q u a t 4 o r TPA, t h e n washed and sub j e c t e d t o t h e normal s y n t h e s i s r e a c t i o n u s i n g 2-exo-Nor as t e m p l a t e . Both XRD and pH ( F i g u r e 6) showed t h a t D i q u a t 4 g r e a t l y r e t a r d e d t h e c o n v e r s i o n t o SSZ-13 and t h a t TPA d i d n o t r e t a r d t h e c o n v e r s i o n . Two f a c t o r s may be r e s p o n s i b l e f o r t h i s d i f f e r e n c e i n b l o c k i n g c o n version. The d i f f e r e n c e i n s h i e l d i n g o f t h e c h a r g e d n i t r o g e n b y t h e m e t h y l v e r s u s t h e p r o p y l groups s h o u l d f a v o r s t r o n g e r r e t e n t i o n o f the D i q u a t 4. A l s o , t h e D i q u a t 4 may have t h e advantage o f a " b i d e n t a t e l i g a n d " i n i t s exchange r e t e n t i o n on t h e C u b i c Ρ s u r f a c e . Discussion A number o f t e m p l a t e s h a v i n g t h e trimethylammonium group a t t a c h e d t o a c y c l o h e x a n e r i n g (and d e r i v a t i v e s t h e r e o f ) produce t h e h i g h s i l i c a c h a b a z i t e , SSZ-13. The r a t e o f c o n v e r s i o n o f C u b i c Ρ t o SSZ-13 i n c r e a s e s as t h e n o n p o l a r group i n c r e a s e s i n s i z e up t o C group, 1 Q


2. ZONES AND VAN NORDSTRAND Table

Templates in Transformation of Zeolites 21

I I . Q u a t e r n a r y Ammonium Compounds Used i n t h e Conversion

o f Cubic

Compound

C/N

+

(CH ) N Br3

(CH CH ) N Br" Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on April 29, 2016 | http://pubs.acs.org Publication Date: September 21, 1990 | doi: 10.1021/bk-1990-0437.ch002

3

2

+

(CH CH CH ) N Br" 2

+

(

(CH ) N -(CH ) -N (CH ) 2l 3

3

2

4

+

3

4

TMA

8

TEA

12

TPA

3

)

3

+

(CH ) N (CH ) -N (CH ) 2Br3

2

i n T h i s Work

(a)

4

+

Abbreviation

(a)

4

2

+

(a)

4

+

3

Ρ Z e o l i t e t o Organozeolites

6

3

5

Diquat

4

6

Diquat

6

8

3-Quin-OH

(a)

3

+

ON-CH.

Novel Materials in Heterogeneous Catalysis - American Chemical

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