Acidic and Exchange Properties of X and Y Zeolites. Correlation with

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for Some of Them R. BEAUMONT, D. BARTHOMEUF, and Y. TRAMBOUZE Institut de Recherches sur la Catalyse, 39 Boulevard du 11 Novembre 1918, 69-Villeurbanne, France and Faculté des Sciences de Lyon, France

The acidic properties of X and Υ zeolites containing various amounts of Na , Ca , and La ions have been measured. The exchange of one sodium ion by H provides a fraction a of acid site which characterizes the type of the zeolite (X or Y). The number of acid sites provided when calcium or lanthanum ions are exchanged depends mainly on the valency of the ion. The cracking of isooctane (used to study catalytic properties of zeolites) is enhanced considerably by hydrogen. Then a particular kind of sites has hydrogenative properties. Either acidic or catalytic properties are lowered by ions located near or in the supercage, and they increase when inner sites are exchanged. +

2+

3+

+

T ) r o p e r t i e s of zeolites d e p e n d s t r o n g l y o n t h e n a t u r e a n d content of t h e A

c a t i o n . A n u m b e r of investigators h a v e s h o w n that l o c a t i o n of cations

is i m p o r t a n t to consider. It d e p e n d s o n s e v e r a l factors, s u c h as the v a l e n c y of t h e i o n a n d the p r e t r e a t m e n t

temperature.

T h e r e f o r e , i t is r a t h e r

difficult to c o m p a r e different catalysts i f t h e y d o n o t c o n t a i n exactly t h e same n u m b e r of m e t a l l i c ions a n d h a v e n o t b e e n heat-treated i n t h e same way. F o r a g i v e n m e t a l l i c i o n , n e i t h e r the a c i d i t y n o r t h e c a t a l y t i c a c t i v i t y are d i r e c t l y p r o p o r t i o n a l to c a t i o n content, a n d the relations

between

these factors are rather c o m p l e x ( I , 2, 7, 8, 9, 11-19). I n o r d e r to h a v e a better u n d e r s t a n d i n g of the correlations b e t w e e n different p r o p e r t i e s , w e w i l l first s y s t e m a t i c a l l y s t u d y the v a r i a t i o n of 327

Flanigen and Sand; Molecular Sieve Zeolites-II Advances in Chemistry; American Chemical Society: Washington, DC, 1971.

328

M O L E C U L A R SIEVE ZEOLITES

a c i d p r o p e r t i e s w i t h the degree o f e x c h a n g e o f N a

+

ions b y p r o t o n s , de

s c r i b i n g t h e results c o n c e r n i n g o n l y t h e w h o l e a c i d i t y , B r o n s t e d L e w i s , w i t h o u t t r y i n g to d i s t i n g u i s h b e t w e e n

II

the 2 forms.

and/or

Different

strengths o f a c i d i t y w i l l b e p o i n t e d o u t w h e n i n c r e a s i n g t h e d e g r e e o f exchange. Results o b t a i n e d l e a d t o extension o f t h e s t u d y to t h e case o f p o l y v a l e n t ions i n o r d e r to v e r i f y t h e h y p o t h e s i s o f p a r t i a l n e u t r a l i z a t i o n o f a c i d i t y b y b i - o r t r i v a l e n t ions. C r a c k i n g o f isooctane

is u s e d t o c h e c k

catalytic activity of pro

gressively e x c h a n g e d N a - z e o l i t e s a n d t o t r y to correlate a c i d a n d c a t a l y t i c properties.

Experimental Materials and Sample Preparation. T h e s t a r t i n g materials a r e c o m m e r c i a l U n i o n C a r b i d e zeolites N a X a n d N a Y , i n p o w d e r f o r m . T h e chemical compositions are N a ( A l O ) 6 ( S i O ) i 0 6 * * H 0 a n d N a 8 6

(A10 )56(Si0 )i36 * x H 2

2

2

2

8

2

2

5 6

0 , respectively.

T h e s o d i u m - a m m o n i u m forms ( N a - N H - X a n d N a - N H - Y ) were prepared b y repeated exchange of the s o d i u m zeolite w i t h a m m o n i u m acetate solutions at r o o m t e m p e r a t u r e . T h e s o d i u m - h y d r o g e n forms ( N a - H - X a n d N a - H - Y ) w e r e o b t a i n e d b y h e a t i n g the a m m o n i u m z e o l i t e at 3 8 0 ° C f o r 15 h o u r s . S e v e r a l c a t i o n i c f o r m s w e r e p r e p a r e d f r o m N a - Y . N e a r l y 9 5 % of N a ions w e r e e x c h a n g e d b y Κ a n d C a ions w i t h c h l o r i d e solutions. T h e s e zeolites n a m e d K - Y a n d C a - Y w e r e p r o g r e s s i v e l y e x c h a n g e d b y N H ions a n d t r a n s f o r m e d i n K - H - Y a n d C a - H - Y f o r m s . L a ions w e r e i n t r o d u c e d i n a z e o l i t e N H - Y , i n w h i c h the r e s i d u a l s o d i u m content is o n l y 1 % , b y r e p e a t e d e x c h a n g e w i t h L a C l ^ solutions. T h e samples w e r e h e a t e d i n d r y air at 3 8 0 ° a n d 5 5 0 ° C f o r 15*hours. X - r a y d i f f r a c t i o n studies s h o w e d that t h e s t r u c t u r e o f N a - X is d e s t r o y e d i f m o r e t h a n 5 0 % o f N a ions a r e e x c h a n g e d b y N H ions. F o r a l l other catalysts, x - r a y d i f f r a c t i o n measurements s h o w t h e samples to be h i g h l y c r y s t a l l i n e . Since zeolites d i f f e r f r o m e a c h other i n the content a n d a t o m i c w e i g h t of the cations, a l l results ( a c i d i t y a n d c a t a l y t i c a c t i v i t y ) are expressed f o r a unit cell. Technique. ACIDITY. T h e n u m b e r o f a c i d sites w a s d e t e r m i n e d b y t i t r a t i o n w i t h n - b u t y l a m i n e . H a m m e t t a n d a r y l m e t h a n o l i n d i c a t o r s chosen a c c o r d i n g t o D r u s h e l a n d S o m m e r s ' studies (4) w e r e u s e d to o b t a i n t h e catalyst a c i d i t y i n terms o f a c i d strength ( 7 ). N u m e r i c a l results o b t a i n e d b y this m e t h o d a r e s i m i l a r to those o b t a i n e d b y other m e t h o d s , f o r ex a m p l e , a d s o r p t i o n (1, 14, 15). CATALYTIC ACTIVITY. T h e c r a c k i n g o f isooctane w a s s t u d i e d . F o r c a t a l y t i c a c t i v i t y measurements, t h e samples w e r e h e a t e d i n flowing h e l i u m o r h y d r o g e n f r o m r o o m t e m p e r a t u r e to 4 6 5 ° C f o r 15 h o u r s . T h e n the gas s a t u r a t e d w i t h isooctane p a s s e d t h r o u g h t h e catalyst i n the m i c r o reactor a n d w a s a n a l y z e d b y gas c h r o m a t o g r a p h y . 4

4

4

4

4


64.

BEAUMONT E T

AL.

Acidic

10

20

and

Exchange

Properties

329

4

0

30

40

50

η

Figure 1.

Acidity as a function of η Na ions exchanged per +

U.C.

NaHY 1 2

NaHX a

Hammett indicator (3.10~*% H,S0 ) Arylmethanol (50% H£O )

4

c

Arylmethanol (88%

3

b

4/

Arylmethanol (77%

h

H*SC\)

H SOO 2

Results Acidity. Z E O L I T E S N A - H - X A N D N A - H - Y . F i g u r e 1 shows the increase of a c i d i t y (at least e q u a l i n strength to the a c i d strength n o t e d ) vs. the n u m b e r of s o d i u m ions e x c h a n g e d p e r u n i t c e l l . C u r v e s c o n c e r n i n g N a - H - X are meaningless w h e n the degree of ex change is greater t h a n 5 0 % ; the c r y s t a l l i n e structure is d e s t r o y e d . F o r zeolites X a n d Y , 2 i m p o r t a n t facts m a y b e d e d u c e d f r o m F i g u r e 1. F o r a g i v e n t y p e of zeolite X a n d Y , the slopes of the straight lines are s i m i l a r , regardless of i n d i c a t o r ( H a m m e t t or a r y l m e t h a n o l ) a n d strength of a c i d i t y . S e c o n d l y , the a c i d i t y A is a l i n e a r f u n c t i o n of the n u m b e r Ν of e x c h a n g e d ions A = aN + b. N u m e r i c a l values of a c a n be d e t e r m i n e d f r o m the straight lines of F i g u r e 1 w i t h i n a n error of ± 4 % . ( T h e coefficient b w i l l n o t be dis cussed h e r e . ) T h e slope a gives the n u m b e r of equivalents of a c i d i t y p r o v i d e d b y the exchange of one e q u i v a l e n t of N a i o n . +

F o r N a Y , w h e n less t h a n 3 7 - 3 8 atoms h a v e b e e n e x c h a n g e d , a = 0 . 7 8 . T h i s cannot be r e l a t e d to a r e s t r i c t i o n i m p o s e d b y the large molecules of


330

M O L E C U L A R SIEVE ZEOLITES

II

b u t y l a m i n e a n d i n d i c a t o r s , since results o b t a i n e d b y N H a d s o r p t i o n g i v e 3

yet s m a l l e r values f o r α ( 1 ). F u r t h e r m o r e , the v a l u e o f a o n l y d e p e n d s o n the valencies o f the cations, not o n t h e i r size—i.e., not o n the size o f the p o r e .

T h e value of a =

1 ( m o r e t h a n 37-38 atoms h a v e b e e n ex

c h a n g e d ) w i l l b e discussed f u r t h e r . T h e slope f o r zeolite X is o n l y 0.22. T h e difference b e t w e e n t h e 2 slopes

(0.22 a n d 0.78) c a n b e e x p l a i n e d o n l y i n terms

of chemical

structure. F i g u r e 1 a n d T a b l e I s h o w that f o r zeolites X a n d Y the n u m b e r o f e x c h a n g e d N a ions itself is n o t i m p o r t a n t , b u t i n o r d e r to get s t r o n g a c i d +

sites the ratio n

N a

/^

0

% m u s t b e the same.

T h i s result emphasizes t h e l o c a t i o n o f sites i n h y d r a t e d zeolites X a n d Y . Sites Si (16 p e r u n i t c e l l ) a r e i n t h e h e x a g o n a l p r i s m b e t w e e n sodalite cages.

Sites S

(32 p e r u n i t c e l l ) are l o c a t e d o n t h e f r e e six-

n

m e m b e r e d rings o f o x y g e n of the sodalite cage; sites S

m

( Y : 8 a n d X : 48

p e r u n i t c e l l ) are l o c a t e d o n the w a l l s o f the large c a v i t y

(supercage).

I n d e h y d r a t e d f o r m s , Sr a n d S ' l i e i n s i d e the sodalite cage a n d face n

Sj a n d S

n

across the r e l e v a n t h e x a g o n a l w i n d o w s . T h e y m a y b e o c c u p i e d

at the expense of S

m

sites ( 5 ).

I n h y d r a t e d f o r m s i n s o l u t i o n , S h e r r y (12) has s h o w n that S are e x c h a n g e d first, t h e n sites S

n

sites

m

a n d Si. T h e results d e s c r i b e d here l e a d

us to a s i m i l a r c o n c l u s i o n ( F i g u r e 1 a n d T a b l e I ) . T h e t i t r a t i o n o f t h e a c i d i t y i n d e h y d r a t e d catalysts b y b u t y l a m i n e , w h i c h p r o b a b l y o n l y goes t h r o u g h larger cavities, d e p e n d s o n several factors, p a r t i c u l a r l y t h e interactions i n t h e supercage.

T h e acidity of

one a c i d site w h i c h has b e e n e x c h a n g e d m a y b e p a r t i a l l y l o w e r e d b y the neutralization b y a N a

i o n c o m i n g f r o m another p o s i t i o n , since u n d e r

+

h e a t i n g ions h a v e the o p p o r t u n i t y to m i g r a t e a n d t h e n t o lose t h e i r m o b i l i t y b y d e h y d r a t i o n (6, 10, 14, 16). T h e greater the n u m b e r o f cations i n the supercage, the greater w i l l be this n e u t r a l i z a t i o n effect. T h e a c i d i t y of X zeolites w h i c h c o n t a i n m o r e ions i n ( o r n e a r ) t h e s u p e r c a g e t h a n Y zeolites w i l l b e m u c h l o w e r e d . T h e n α ( X ) is s m a l l e r t h a n a ( Y ) . Table I.

Effect of » N a / o n

Zeolite Acid %

Strength, H SO, 2

ftNa

0 19 27

*°

+

Na-H-

07a

n

(X)

-Y n ~

Na

riiVa

riom

0 22 31.5

%8 = n u m b e r of N a ions exchanged; zeolites: X = w (x) = 86; ηο L a ( O H ) + + H + + H 0 2

2

F o r L a z e o l i t e , t h e slopes a

L a

. o and a 30

L a

2

- 550 v e r i f y the assumptions b a s e d

o n results o b t a i n e d b y different e x p e r i m e n t a l m e t h o d s ( i n f r a r e d analysis and E P R ) . I n c o n c l u s i o n , f o r a l l t h e samples s t u d i e d , values o f a a n d t h e i r r a t i o e x p l a i n t h e a c i d p r o p e r t i e s o f M e - H - Y zeolites, c o m p l e t i n g results a l r e a d y known.

I n p a r t i c u l a r , t h e constant v a l u e of a w i t h i n a l a r g e degree of

exchange a n d f o r s e v e r a l a c i d strengths verifies t h e p o s t u l a t e d a c i d p r o p erties o f zeolites c o n t a i n i n g b i - a n d t r i v a l e n t cations w h e n v a r y i n g ex change o r a c i d strength.

T h e m e t h o d of d e t e r m i n i n g t h e slope a c a n

b e a p p l i e d to other p o l y v a l e n t ions a n d r a p i d l y p r o v i d e s easily u n d e r s t a n d a b l e results. T h e good agreement between

slopes, ratios, a n d valencies

shows

that t h e slope a d e p e n d s m a i n l y o n v a l e n c y a n d that other factors s u c h as t h e i o n size are o f m i n o r i m p o r t a n c e .

I

I

I

I

I

I

0

10

20

30

40

50

•

η

Figure 3.

Catalytic activity of NaHY (v = initial rate for isobutene pro duction) as a function of η Na ions exchanged per U.C. 0

+

a = Helium stream b = Hydrogen stream


334

M O L E C U L A R

SIEVE

ZEOLITES

Π

C a t a l y t i c A c t i v i t y . T h e c a t a l y t i c p r o p e r t i e s of N a H Y zeolites w e r e s t u d i e d . Results are s h o w n i n F i g u r e 3. A s e m i l o g a r i t h m i c scale is chosen to s h o w m o r e c l e a r l y t h e v a r i a t i o n of a c t i v i t y f o r a n exchange i n c l u d i n g 1 7 - 3 7 atoms. T h e increase of c a t a l y t i c a c t i v i t y w i t h i o n exchange has a l r e a d y b e e n s h o w n . F i g u r e 3 indicates that results d e p e n d o n e x p e r i m e n t a l factors. C u r v e a deals w i t h h e l i u m as c a r r i e r gas, r e s e m b l i n g p u b l i s h e d curves o b t a i n e d w i t h the same gas ( 1 5 , 19).

O n the other h a n d , c u r v e b ( h y

d r o g e n stream ) is s i m i l a r to results of b e n z e n e a l k y l a t i o n w i t h p r o p y l e n e (8).

I n this w o r k , the authors s t u d i e d c a t a l y t i c a c t i v i t y w i t h the exchange

of N a f o r C a +

2 +

ions. Si sites are o c c u p i e d either b y N a o r b y C a +

2 +

ions,

a n d n o effect c a n b e seen of t h e influence of t h e exchange o n a c t i v i t y of the last sites. A c c o r d i n g l y , c u r v e a ( F i g u r e 3 ) , l i m i t e d to a n exchange f r o m 0 to 28 ions, is exactly s i m i l a r to curves o b t a i n e d f o r b e n z e n e a l k y l a tion

(8). F i g u r e 3 shows that u p to t h e exchange of n e a r l y 17 N a ions there +

is n o difference a t t r i b u t a b l e to the n a t u r e of the gas. B e y o n d this p o i n t , a r a p i d increase i n a c t i v i t y is m e a s u r e d w i t h h y d r o g e n b u t n o t w i t h helium.

A s e c o n d a n d i m p o r t a n t increase starts w i t h the exchange

3 7 - 3 8 N a ions. greater.

of

A t the same t i m e , a c t i v i t y i n h e l i u m r a p i d l y b e c o m e s

T h e h i g h e r effectiveness

d e s c r i b e d (15, 19).

of t h e last-exchanged sites has b e e n

Results a n d conclusions of the s t u d y of a c i d i t y d e

s c r i b e d i n the first p a r t of this p a p e r s h o w that u p to 3 7 - 3 8 ions ex c h a n g e d , properties i n the supercage d e p e n d o n N a ions i n ( o r near ) the +

supercage.

B e y o n d this v a l u e , slope a increases,

a n d the a c i d i t y o n l y

d e p e n d s o n the n u m b e r of last-exchanged sites. T h e n properties i n d u c e d i n the supercage b y u n o c c u p i e d last-exchanged

sites g r e a t l y differ i n

n a t u r e f r o m properties i n the supercage before t h e i r

exchange.

U p to 3 7 - 3 8 atoms, c a t a l y t i c p r o p e r t i e s are l o w e r e d b y cations i n ( o r n e a r ) the supercage.

A f t e r 3 7 - 3 8 atoms e x c h a n g e d , c a t a l y t i c a c t i v i t y

d e p e n d s o n the n e w p r o p e r t i e s i n the supercage o w i n g to r e p l a c e m e n t of s o d i u m i o n i n i n n e r sites, w h a t e v e r b e t h e n a t u r e of the gas. I n h y d r o g e n atmosphere,

the first increase i n a c t i v i t y f o r t h e ex

c h a n g e of 17 ions m a y b e e x p l a i n e d p a r t i a l l y a c c o r d i n g to the v i e w s of R u b i n s t e i n et al. (8).

T h e y d e m o n s t r a t e d that c a t a l y t i c a c t i v i t y varies,

f o r this degree of exchange, w i t h the n u m b e r of u n o c c u p i e d S

n

sites.

N e v e r t h e l e s s , c u r v e b of F i g u r e 3 shows some other p r o p e r t i e s of zeolites (2).

T h e specific effect of h y d r o g e n is detected f o r a l l the p r o d u c t s o b

t a i n e d i n isooctane c r a c k i n g ( p r o p e n e , isobutene, isobutane, Nevertheless, the rise i n a c t i v i t y ( f r o m H e to H

2

2-butene).

f o r a g i v e n degree of

e x c h a n g e ) varies f r o m 9 f o r isobutane to 3 a n d 2 f o r p r o p e n e a n d iso b u t e n e , r e s p e c t i v e l y . T h e e n h a n c e m e n t is t h e most i m p o r t a n t f o r i s o b u tane.

S e v e r a l experiments s h o w e d that isobutane comes f r o m isobutene


64.

BEAUMONT ET

hydrogénation.

AL.

Acidic

and

Exchange

Properties

335

H i g h a c t i v i t y f o r isobutane p r o d u c t i o n is l i n k e d to h y d r o -

g e n a t i n g properties of the zeolites e m p l o y e d . T h e increase i n p r o d u c t i o n of other h y d r o c a r b o n s m a y b e e x p l a i n e d as f o l l o w s : as i n b i f u n c t i o n a l catalysts, some sites of e m p l o y e d z e o l i t e are active i n

hydrogénation

reactions, f o r m i n g h e a v y p r o d u c t s of the isooctane c r a c k i n g . T h i s p r e vents c o k e d e p o s i t i o n a n d increases

the w h o l e c a t a l y t i c a c t i v i t y .

Iso

b u t e n e , w h i c h c a n b e h y d r o g e n a t e d easily, gives m o r e i s o b u t a n e t h a n i n absence of h y d r o g e n . T h i s e x p l a n a t i o n is c o r r o b o r a t e d b y the c o l o r of the zeolite after the c r a c k i n g r e a c t i o n : samples are grey i n H He

2

and black i n

stream. T h e effect of h y d r o g e n a t i n g sites is o n l y i m p o r t a n t w h e n the exchange

increases f r o m 17 to 3 7 - 3 8 atoms.

A f t e r that, the influence of Si sites

p r e v a i l s a n d h y d r o g e n a t i n g properties

decrease.

A c c o r d i n g l y , for successive exchanges of sites, h y d r o g e n a t i n g p r o p erties m a y come f r o m a f r a c t i o n of S

n

sites.

Conclusions T h e a c i d i t y of p r o g r e s s i v e l y e x c h a n g e d zeolites has b e e n s t u d i e d , p r o v i d i n g the n u m b e r of a c i d sites (a)

o b t a i n e d w h e n one

equivalent

of m e t a l l i c i o n is r e m o v e d . It m a y be c o n s i d e r e d that a characterizes the a c i d i c efficiency of one e x c h a n g e d site a n d is i n d e p e n d e n t of the a c i d strength b u t d e p e n d s o n 3 main

factors:

F o r a g i v e n c a t i o n ( N a ) a n d w h e n the degree of exchange is not +

too h i g h , a varies w i t h the t y p e of zeolite X a n d Y . T h i s effect has to b e c o n n e c t e d to the n u m b e r of ions w h i c h are l o c a t e d i n ( o r n e a r )

the

supercage. F o r a g i v e n cation ( N a ) a n d a g i v e n t y p e of zeolite ( Y ) , a d e p e n d s +

o n the l o c a t i o n of the ions. T h i s factor is l i n k e d to the degree of exchange; i.e., a < 1 w h e n there are ions i n ( o r n e a r ) the supercage a n d a =

1 when

these ions are a l l r e m o v e d a n d therefore the i n n e r sites are e x c h a n g e d . F o r a g i v e n t y p e of zeolite, a d e p e n d s m a i n l y o n the v a l e n c y of the c a t i o n ; other factors s u c h as i o n size are of m i n o r i m p o r t a n c e . C a t a l y t i c a c t i v i t y is i n f l u e n c e d also b y ions i n ( o r n e a r ) the supercage. A s l o n g as these ions are not e x c h a n g e d , the c r a c k i n g of isooctane is not i m p o r t a n t . I n N a - H - Y zeolites, o n l y the exchange of the last ions n o t i c e a b l y increases it. A c i d a n d c a t a l y t i c studies enable us to assume that cations l o c a t e d near the w a l l s of the supercage r e d u c e the a b i l i t y a n d change the c h a r acter of m o l e c u l e a d s o r p t i o n o n the a c i d a n d active sites. A f t e r the w h o l e exchange of these cations, the r e m o v a l of ions f r o m the i n n e r sites leads to another k i n d of a d s o r p t i o n of the m o l e c u l e s .


336

MOLECULAR SIEVE ZEOLITES II

F u r t h e r m o r e , h y d r o g e n a t i n g p r o p e r t i e s are d e t e c t e d f o r i n t e r m e d i a t e degrees o f exchange. S o m e e x c h a n g e d sites i n t h e s u p e r c a g e c a n h y d r o genate olefins.

Literature Cited (1) Bandiera, J., Ben Taarit, Y., Naccache,C.,Bull. Soc. Chim. France 1969, 3419. (2) Beaumont, R., Barthomeuf, D., Compt. Rend. Acad. Sci. Paris, 1969, C, 269, 617. (3) Ben Taarit, Y., Bandiera, J., Mathieu, M. V., Naccache,C.,J.Chim. Phys. 1970, 67, 37. (4) Drushel, H. V., Sommers, A. L., ACS, New York Meeting, 1966. (5) Eulenberger, G. R., Shoemaker, D. P., Keil, J. G., J. Phys. Chem. 1967, 71, 1812. (6) Freeman,D.C.,Stamires, D. N., J. Chem. Phys. 1961, 35, 799. (7) Hirschler, A. E.,J.Catalysis 1963, 5, 428. (8) Isakov, Ya. I., Klyachko-Gurvich, A. L., Khudiev, A. T., Minachev, Kh., Rubinstein, A. M., Intern. Congr. Catalysis, 4th, Moscow 1968, paper 56. (9) Olson, D. H., Dempsey, E. J.,J.Catalysis 1969, 13, 221. (10) Olson, D. H., Kokotailo, G. T., Charnell, J. F., Nature 1967, 215, 270. (11) Rabo, J. Α., Pickert, P. E., Stamires, D. N., Boyle, J. E., Proc. Intern. Congr. Catalysis, 2nd, Paris 1960, 2, 2055. (12) Sherry, H. S., J. Phys. Chem. 1966, 70, 1158. (13) Turkevich, J., Catalysis Rev. 1967, 1, 1. (14) Turkevich, J., Murakami, Y., Nozaki, F., Ciborowski, S., Chem. Eng. Progr. Symp. Ser. 1967, 63, 75. (15) Turkevich, J., Nozaki, F., Stamires, D. N., Proc. Intern. Congr. Catalysis, 3rd, Amsterdam 1965, 1, 586. (16) Uytterhoeven, J. B., Jacobs, P., Makay, K., Schoonheydt, R., J. Phys. Chem. 1968, 72, 1768. (17) Venuto, P. B., Hamilton, L. Α., Landis, P. S.,J.Catalysis 1966, 5, 484. (18) Ward, J. W., J. Catalysis 1969, 13, 321. (19) Ward, J. W., Hansford, R.C.,J. Catalysis 1969, 13, 364. RECEIVED February 4, 1970.


Acidic and Exchange Properties of X and Y Zeolites. Correlation with

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