Adsorption and Ion Exchange with Synthetic Zeolites - American

9 Preparation of Copper(II)-Exchanged Y Zeolites from Sodium and Ammonium Y Zeolites Downloaded by UNIV OF CALIFORNIA SAN FRANCISCO on December 12, 2014 | http://pubs.acs.org Publication Date: August 15, 1980 | doi: 10.1021/bk-1980-0135.ch009

RICHARD G. HERMAN and JOHN B. BULKO Center for Surface and Coatings Research, Sinclair Laboratory, Building #7, Lehigh University, Bethlehem, PA 18015

The preparation of ammonium ion exchanged Y zeolites has long been known to be a precursor step in the preparation of H Y zeolites. The former materials have been characterized by thermogravimetric experiments, while the latter zeolites that contain the H atoms as hydroxyl groups have been intensively examined by infrared spectroscopy (1,2,3,4). A systematic description of the preparation of NH Y zeolites has apparently not been reported, although an ion exchange isotherm for the Na-NH exchange at 25°C has been given (5). Divalent copper Y zeolites have been widely prepared and the Cu(II)-Na exchange process has been described by ion exchange isotherms (5,6). It was clearly shown that Y zeolite exhibited a strong preference for Cu(II) over Na . Similar behavior might be expected for the Cu(II)-NH ion exchange, although hydrogen bonding by the ammonium ion in the hydrated zeolite lattice might influence the ion exchange process. Clarification of the practical preparative relationships involved in the Cu(II)-NH -Na Y zeolite system is desired because of developing industrial application of these materials. For example, Cu-H-Na Y zeolites (7) and Cu-H-RE Y zeolites (8), where RE = rare earth, have been found to be excellent cracking catalysts that produce high octane gasoline having enhanced aromatic and olefinic content. In addition, i t has been observed recently that Cu-H Y zeolites efficiently adsorb NH from gas streams containing low concentrations of this impurity (9). 4

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Experimental Ammonium Ion Exchange. Linde anhydrous Na Y z e o l i t e was used as r e c e i v e d t o prepare NH^* i o n exchanged samples. The general procedure was t o add the z e o l i t e t o 1.0 M NH.NOg s o l u t i o n at a designated temperature (23, 50, 65, 85, o r 100°S) such t h a t the r a t i o o f s o l u t i o n volume t o s o l i d mass (v/m) was 20 cm /g. The mixture was s t i r r e d continuously f o r 4 h, allowed t o stand f o r 5 min, and then the supernatant was decanted and the s o l i d 0-8412-0582-5/80/47-135-177$05.00/0 © 1980 American Chemical Society

In Adsorption and Ion Exchange with Synthetic Zeolites; Flank, W.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

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was f i l t e r e d onto Whatman #2 f i l t e r paper with the a i d o f s u c t i o n . The z e o l i t e was washed w i t h 10 cm p o r t i o n s o f water, where t o t a l v/m = 20 cm /g, and added t o a f r e s h a l i q u o t of ammonium n i t r a t e s o l u t i o n . A f t e r t h i s procedure was once again repeated, the r e s u l t a n t z e o l i t e was d r i e d at ambient temperature i n an open v e s s e l p l a c e d i n a fume hood.

Downloaded by UNIV OF CALIFORNIA SAN FRANCISCO on December 12, 2014 | http://pubs.acs.org Publication Date: August 15, 1980 | doi: 10.1021/bk-1980-0135.ch009

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Copper(II) Ion Exchange. S t a r t i n g w i t h anhydrous Na Y and hydrated NH^ Y z e o l i t e s , i o n exchange was c a r r i e d out w i t h f i l tered Cu(N0 ) *3H 0 solutions of d i f f e r e n t concentrations i n order t o o b t a i n samples w i t h d i f f e r e n t Cu(II) contents. The e q u i l i b r a t i o n s were c a r r i e d out f o r 4 h at ambient temperature w i t h v/m = 20 o r 200 cm /g. 3

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An a d d i t i o n a l s e r i e s o f samples o f Na Y was e q u i l i b r a t e d w i t h 0.01 M Cu(II) s o l u t i o n s , v/m = 20 cm /g, i n which the pH was a r t i f i c i a l l y adjusted t o 3.0, 5.0, or 9.0. For the a c i d s o l u t i o n e q u i l i b r a t i o n s , the copper(II) n i t r a t e s o l u t i o n s were adjusted to the d e s i r e d pH by the a d d i t i o n o f 1.0 M HNO^ or 0.1 M NaOH. A f t e r the a d d i t i o n of the z e o l i t e , which had been s l u r r i e d i n a s m a l l amount o f water, the s o l u t i o n was c o n t i n u o u s l y s t i r r e d f o r 4 h at ambient temperature. The pH was monitored and maintained at the r e q u i r e d v a l u e s . For the p r e p a r a t i o n of the sample a t pH = 9.0, the Na Y z e o l i t e was added t o water (v/m = 10 cm /g) and the pH was decreased t o 6.0 by the a d d i t i o n o f 1.0 Μ Η Ν 0 · F o l l o w i n g the a d d i t i o n o f the Cu(II) s o l u t i o n , the pH was i n c r e a s e d t o pH 9 by means o f 0.1 M NaOH over a p e r i o d o f 0.5 h. S t i r r i n g was continued f o r 3.5 h, d u r i n g which time the pH was maintained a t 9.0. 3

Analyses. Ammonium i o n - c o n t a i n i n g samples were analyzed commercially f o r Ν, H, and Na content. The copper(II) concen t r a t i o n s were determined commercially and by atomic a b s o r p t i o n o r spectrophotometric measurements a) on the p r e p a r a t i v e f i l t r a t e s , b) f o l l o w i n g back-exchange o f the z e o l i t e s by Ag , and/ o r c) f o l l o w i n g complete d i s s o l u t i o n o f the z e o l i t e s . Results Ammonium Ion Exchanged Y Z e o l i t e s . The e f f e c t t h a t e q u i l i b r a t i o n temperature exerted upon the degree of N H i o n exchange o f Na Y z e o l i t e was s t u d i e d i n t h i s p a r t o f the i n v e s t i g a t i o n . The r e s u l t s o f two o f the f i v e t r i p l e e q u i l i b r a t i o n s are shown i n F i g u r e 1. Sample C was found t o correspond t o N a ( N H ) ( A 1 0 ) (SiO ) -200H Ο [Found: 0.81 wt % Na, 4.32 wt % N, 3.62 wt % H; C a l c u l a t e d : 0.86 wt % Na. 4.35 wt % N, 3.73 wt % Η ] , while sample F was determined t o be N a ( N H ) ( A 1 0 ) ( S i 0 ) •200H 0 [Found: 1.95 wt % Na, 3.59 wt % N, 3.57 wt % H; C a l c u l a t e d : 1.99 wt % Na, 3.64 wt % N, 3.52 wt % H]. After a single 4 h e q u i l i b r a t i o n , the samples prepared a t the f i v e designated temperatures were observed t o be 68-71 % exchanged by NH. , and +

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t h e a n a l y t i c a l data f o r sample D wt % Ν, 3.43 wt % H; C a l c u l a t e d : 2.56 wt % Η ] , which i s t y p i c a l o f these Na._(NHJ (A10 )_^(SiO_) ·200Η 0. + Ιο 4 JO Δ DO Δ lob Δ The extent o f NH. i o n exchange a f t e r t r i p l e e q u i l i b r a t i o n s i s shown i n F i g u r e 2 t o correspond d i r e c t l y w i t h the temperature. The supernatant pH f o r these samples was 5.3 ± 0.2, while the pH a f t e r a s i n g l e équilibration» e.g. samples A and D i n F i g u r e 1, was 6.5 ± 0.2. oe

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Copper(II) Ion Exchanged Y Z e o l i t e s . The z e o l i t e s u t i l i z e d were the parent anhydrous Na Y z e o l i t e [ N a ( A 1 0 ) ( S i 0 ) and the hydrated NH Y z e o l i t e s designated as samples C and F i n the p r e v i o u s s e c t i o n . Upon Cu(II) i o n exchange o f Na Y z e o l i t e a t ambient temperature w i t h t h e c o n s t r a i n t o f v/m = 20 cm /g, the f i n a l pH was found t o be p r o p o r t i o n a l t o the i n i t i a l copper(II) c o n c e n t r a t i o n i n s o l u t i o n as shown by the semi-log p l o t i n F i g ure 3. The i n i t i a l pH o f the exchange s o l u t i o n was, i n each case, the v a l u e expected f o r t h e designated copper(II) n i t r a t e concentration. I n c r e a s i n g v/m by a f a c t o r o f 10 r e s u l t e d i n a curve t h a t appeared t o c o n s i s t o f two l i n e a r r e g i o n s . A t low copper(II) c o n c e n t r a t i o n s , i t i s apparent i n F i g u r e 3 t h a t one o f the l i n e a r p o r t i o n s o f the curve i s p a r a l l e l t o the s t r a i g h t l i n e obtained when v/m = 2 0 cm /g. Using hydrated NH Y z e o l i t e s as s t a r t i n g m a t e r i a l s , s i m i l a r behavior was observed. Most o f the data p o i n t s i n F i g u r e 3 f o r the Cu(II) + NH Y exchange were obtained u s i n g Sample C, which was d e p i c t e d i n F i g u r e s 1 and 2 (89% N H exchanged). However, the three data p o i n t s f o r v/m = 20 cm /g designated by t r i a n g l e s i n F i g u r e 3 were obtained w i t h Sample F (75% NH exchanged). I d e n t i c a l exchange behavior f o r these two samples i s demonstrated by the s i n g l e curve drawn through the two s e t s o f data p o i n t s f o r v/m = 20 cm /g. Although the f i n a l pH was always a c i d i c , v i b r a t i o n a l s t u d i e s showed t h a t the unexchanged N H i o n s remained i n the z e o l i t e s i n s t e a d o f being r e p l a c e d by H+ ions ( 9 ) . F o l l o w i n g analyses o f most o f the samples i n d i c a t e d i n F i g ure 3, the curves shown i n F i g u r e 4 were c o n s t r u c t e d . A d d i t i o n a l p o i n t s corresponding t o e q u i l i b r a t i o n o f Na Y samples i n d i s t i l l e d water f o r 4 h a r e i n c l u d e d i n the p l o t a t pH = 10.32(v/m = 20 cm /g) and a t pH = 9.21 (v/m = 200 cm / g ) . I t i s e v i d e n t from t h i s f i g u r e t h a t , under the c o n d i t i o n s t h a t these experiments were c a r r i e d out, a maximum o f 71% copper(II) exchange was achieved w i t h the NH Y z e o l i t e s . A lower exchange l e v e l was a t t a i n e d by the Na Y z e o l i t e s when e q u i l i b r a t e d w i t h the same copper-containing s o l u t i o n s . Higher copper(II) i o n exchange was observed w i t h t h e two v/m = 200 cm /g s e r i e s than w i t h t h e v/m = 20 cm /g s e r i e s , as would be expected s i n c e the q u a n t i t y o f copper i s 10 times g r e a t e r w i t h r e s p e c t t o t h e z e o l i t e i n the former as compared w i t h t h e l a t t e r . The a n a l y t i c a l r e s u l t s f o r the Na Y samples t h a t had been 5 6

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Figure 1. The extent of ammonium ion exchange of Νa Y zeolite (A)at23°C and at (O) 85°C. Equilibrations of the solu tions with v/m = 20 cm /g were carried out for 4 hr each. 3

Figure 2. The degree of ammonium ion exchange of Να Y zeolite following triple equilibrations at selected temperatures. Points C and F correspond to the desig nated data points in Figure 1.

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Figure 3. The final pH of the solutions following ion exchange of (%, Ο) Να Y, (Μ, Π) NH Y—89% exchanged, and (A) NH> Y—75% exchanged zeolites by Cu(II) solutions of various concentrations at ambient temperature. The curves correspond to series of samples prepared with v/m = 20 cm /g (filled symbols) or 200 cm /g (open symbols). h

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Figure 4. The percent Cu(II) exchange of (Φ, Ο) Να Y, fl, Π) ^H Y—89% exchanged, and (A) NH Y—75% exchanged zeolites as a function of the final solution pH, which was altered by varying v/m from 20 cm /g (filled symbols) to 200 cm /g (open symbols) and by varying the Cu(II) solution concentration. k

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e q u i l i b r a t e d w i t h 0.01 M Cu(II) s o l u t i o n s a t c e r t a i n c o n t r o l l e d pH v a l u e s are presented i n F i g u r e 5. The copper and sodium i o n c o n c e n t r a t i o n s were determined by atomic a b s o r p t i o n f o l l o w i n g back-exchange with A g , while the hydrogen c a t i o n contents were c a l c u l a t e d by d i f f e r e n c e , assuming a constant t o t a l c a t i o n con t e n t o f 3.2 meq/g o f hydrated Y z e o l i t e . The % copper(II) ex change o f these samples, g i v e n i n t h e order o f i n c r e a s i n g pH, are 3.8, 13, 9.8, and 2.1%. Analyses by X-ray powder d i f f r a c t i o n i n d i c a t e d t h a t none o f these samples s u f f e r e d a l o s s o f c r y s t a l l i n e d u r i n g t h e i o n exchange treatments.


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Discussion Ion Exchange. I t i s e v i d e n t from F i g u r e 1 and the data p r e sented i n the R e s u l t s S e c t i o n t h a t N H was e a s i l y i o n exchanged i n t o Na Y z e o l i t e . During the short e q u i l i b r a t i o n times used i n t h i s study, the N H ions entered the z e o l i t e l a t t i c e and were p r e f e r r e d over N a by t h e supercage s i t e s . However, these mono v a l e n t c a t i o n s d i d not d i s p l a c e t h e sodium ions from the s o d a l i t e cages nor from the hexagonal prisms d u r i n g a s i n g l e e q u i l i b r a t i o n at ambient temperature s i n c e 18 N a i o n s p e r u n i t c e l l were not exchanged. Although i t was shown t h a t a dehydrated Na Y z e o l i t e contained 48% o f the c a t i o n s i n t h e s m a l l cages (10), a s i n g l e c r y s t a l X-ray study o f hydrated [Na,Ca] f a u j a s i t e i n d i c a t e d t h e presence o f 17 c a t i o n s i n the s o d a l i t e cages (11). The p r e s e n t o b s e r v a t i o n s are i n agreement w i t h other i o n exchange s t u d i e s , which showed t h a t e q u i l i b r a t i o n o f Na Y w i t h N H (12) , L a (13) , and C a (14) a t 25°C f o r 24 h o r l e s s d i d not exchange 16 N a ions per u n i t c e l l . Repeated e q u i l i b r a t i o n s w i t h f r e s h ammonium n i t r a t e s o l u t i o n d i d l e a d t o m i g r a t i o n o f some o f the N a i o n s out o f the s m a l l cages and replacement by N H i o n s , and t h i s process was enhanced by e l e v a t e d temperatures, as shown by F i g ures 1 and 2. A l l o f these h i g h l y exchanged N H samples were observed t o c o n t a i n about 200 water molecules p e r u n i t c e l l , i n agreement with a p r e v i o u s r e p o r t (3), although a higher degree o f h y d r a t i o n was r e p o r t e d elsewhere (4). F o r comparison, Na Y z e o l i t e s (15) and Cu-Na Y z e o l i t e s (16) c o n t a i n approximately 260 H 0 / u n i t c e l l when f u l l y hydrated. +

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In comparison w i t h the 68% exchange l e v e l achieved by e q u i l i b r a t i n g Na Y w i t h 1.0 M N H , F i g u r e 4 c o r r e l a t e d w i t h F i g u r e 3 demonstrates t h a t about the same degree o f i o n exchange was ob t a i n e d when Na Y and NH Y-89 z e o l i t e s were e q u i l i b r a t e d with 0.1 M Cu(II) s o l u t i o n s . The 71% copper(II) exchanged sample c o r r e sponds t o N a ( N H ) C u Y z e o l i t e , while N a ( N H ) C u Y repre sents the Cu Y-60 z e o l i t e . These r e s u l t s support the p r o p o s a l t h a t Cu(II) i o n exchange c a r r i e d o u t a t ambient temperature f o r s h o r t e q u i l i b r a t i o n p e r i o d s ( l e s s than 24 h) d i s p l a c e s o n l y the u n i v a l e n t c a t i o n s i n t h e supercages (16,Γ7). A k i n e t i c a l l y con t r o l l e d slow step f o l l o w s i n which the hydrated i o n s , where t h e hydrated r a d i u s o f Cu(II) i s 0.419 nm (18) and t h e hydrated +

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Figure 5. The exchangeable (Q) sodium ion, (O) divalent copper ion, and (A) hydrogen ion content vs pH for Να Y zeolite equilibrated with 0.01M copper(II) nitrate solutions for 4 hr at ambient temperature with v/m = 20 cm /g. s


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r a d i u s o f NH^"" i s 0.331 nm (19), shed water molecules and pass through 0.26 nm windows (maximum e f f e c t i v e diameter) i n t o the s o d a l i t e cages. T h i s process i s enhanced by i n c r e a s i n g the e q u i l i b r a t i o n temperature, which y i e l d s h i g h e r i o n exchange l e v e l s . A f t e r the copper(II) i o n exchange treatments, the f i n a l pH was observed t o be lower, e s p e c i a l l y a t low Cu(II) c o n c e n t r a t i o n s , f o r the Cu-NH^ Y exchanges than f o r the Cu-Na Y exchanges, as shown i n F i g u r e 4. T h i s i s due t o the p r i o r p r e p a r a t i o n o f the NH Y z e o l i t e s , d u r i n g which they were i n e f f e c t prewashed p r i o r t o the Cu(II) i o n exchange. The e f f e c t was much l e s s n o t i c e a b l e w i t h v/m = 200 cm /g than w i t h v/m = 20 cm /g, as would be expected. T h i s d i f f e r e n c e i n f i n a l pH apparently d i d not i n f l u e n c e the r e s u l t a n t degree o f i o n exchange at low copper c o n c e n t r a t i o n . T h i s i s i l l u s t r a t e d by the exchanges c a r r i e d out u s i n g 0.01 M Cu(II) s o l u t i o n . With v/m « 20 cnr/g, both the Na Y and the NH Y z e o l i t e s were 10% i o n exchanged w i t h C u ( I I ) , while w i t h v/m = 200 cm /g the two z e o l i t e s a t t a i n e d 15 and 14% exchange levels, respectively. 4

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Copper(II) Exchange a t C o n t r o l l e d pH Values. The c a t i o n concentrations d i s p l a y e d i n F i g u r e 5 f o r pH 7 were obtained f o l lowing an e q u i l i b r a t i o n w i t h 0.01 M Cu(II) s o l u t i o n t o which no a c i d o r base had been added. T h e r e f o r e , t h i s pH was " n a t u r a l l y " determined by the balance between copper n i t r a t e c o n c e n t r a t i o n and amount o f Na Y z e o l i t e mixed w i t h the s o l u t i o n , as was the case f o r the samples t h a t y i e l d e d the data i n F i g u r e 3. This balance was a l t e r e d by the a d d i t i o n o f a c i d o r base d u r i n g the p r e p a r a t i o n of the three other samples d e p i c t e d i n F i g u r e 5. As the a c i d c o n c e n t r a t i o n was i n c r e a s e d , the q u a n t i t y o f H i o n s i n the z e o l i t e a l s o i n c r e a s e d . The exchange i n a l k a l i n e medium was achieved by mixing the two reagents and then g r a d u a l l y i n c r e a s i n g the pH t o 9. Undoubtedly some i o n exchange occurred d u r i n g t h i s process. Following e q u i l i b r a t i o n and f i l t r a t i o n , the f i l t r a t e was observed t o be c l e a r and c o l o r l e s s w h i l e the d r i e d s o l i d was a l i g h t t a n , as d e s c r i b e d p r e v i o u s l y (16). The c a t i o n concentrations dep i c t e d i n F i g u r e 5 were determined by back-exchange with Ag . A q u a n t i t y o f copper was not removed from the z e o l i t e by the A g back-exchange and was probably present on the z e o l i t e i n the form o f CuO, which would be present i n the amount o f 0.012 g/g o f anhydrous z e o l i t e . +

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Routine P r e p a r a t i o n s . From the d i s c u s s i o n o f F i g u r e 5, i t can be deduced t h a t i t i s p r e f e r a b l e t o c a r r y out i o n exchange o f Y z e o l i t e w i t h copper(II) without a l t e r i n g the r e s u l t a n t pH. The i o n exchange process can be c o n t r o l l e d by the Cu(II) conc e n t r a t i o n i n the e q u i l i b r a t i o n s o l u t i o n , as F i g u r e s 3 and 4 demonstrate. T h e r e f o r e , f o r a 10% Cu(II) exchanged Na Y z e o l i t e , a 0.01 M Cu(II) s o l u t i o n can be used w i t h v/m = 20 cm /g. The r e s u l t a n t pH, which connects F i g u r e 3 w i t h F i g u r e 4, i s 7. 3


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Cu(ll)-Exchanged Y Zeolites

HERMAN AND BULKO

S i m i l a r l y , a 0.10 M Cu(II) s o l u t i o n w i t h NH Y (at v/m = 20 cnr/g) y i e l d e d a 68% Cu (II) exchanged sample i n a pH 4.15 supernatant. The volume o f s o l u t i o n used per g o f z e o l i t e a l s o p l a y s a p a r t i n determining the i o n exchange l e v e l achieved. As p o i n t e d out i n a previous s e c t i o n , i n 0.01 M Cu(II) s o l u t i o n w i t h v/m « 20 cm /g, both Na and NH Y z e o l i t e s a t t a i n e d a 10% Cu(II) ex change l e v e l . I n c r e a s i n g the v/m r a t i o by a f a c t o r o f 10 and d e c r e a s i n g the copper c o n c e n t r a t i o n t o 0.005 M y i e l d e d 9% ex changed samples f o r both Y z e o l i t e s . Thus, F i g u r e s 3 and 4 can be u t i l i z e d t o prepare Na o r NH Y z e o l i t e s having a p r e d e t e r mined Cu(II) content by v a r y i n g a number o f experimental parameters. The approximate l i n e a r i t y o f the v/m = 20 cm /g p l o t s i n F i g u r e 3 i s o f i n t e r e s t . These data p o i n t s represent samples t h a t had r a t h e r l a r g e amounts o f z e o l i t e present i n comparison to the volume o f the s o l u t i o n . I n these p r e p a r a t i o n s , the s o l u t i o n pH was determined by the Na Y z e o l i t e but was moderated by the q u a n t i t y o f copper s a l t i n i t i a l l y p r e s e n t . Increasing the s o l u t i o n volume by a f a c t o r o f 10 y i e l d e d curves having an i n f l e c t i o n p o i n t near a copper c o n c e n t r a t i o n o f 0.01 M. Below t h i s c o n c e n t r a t i o n , the curves are p a r a l l e l t o the corresponding v/m « 20 cm /g curves and a g a i n r e f l e c t the presence o f the z e o l i t e . For the more concentrated copper(II) reagent s o l u t i o n s , however, the f i n a l pH i s determined d i r e c t l y by the s a l t c o n c e n t r a t i o n and not by the z e o l i t e . 4


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Conclusions The p r e p a r a t i v e r e l a t i o n s h i p s between the degree o f i o n ex change o f Na Y and NU Y z e o l i t e s w i t h copper(II) ions as a f u n c t i o n o f the i n i t i a l copper(II) s o l u t i o n c o n c e n t r a t i o n and the r e s u l t a n t pH a f t e r e q u i l i b r a t i o n have been determined. Copper and ammonium i o n s r e a d i l y r e p l a c e sodium i o n s i n t h e supercages, where the s e l e c t i v i t y i s Cu(II) > N H * > N a i n the hydrated z e o l i t e . Repeated e q u i l i b r a t i o n o f Na Y with N H results i n some o f the N a i o n s i n t h e s m a l l cages being exchanged, and e l e vated temperatures enhance t h i s replacement. Graphs have been presented t h a t allow the p r e p a r a t i o n o f Cu(II) i o n exchanged Na Y or NH Y z e o l i t e s having predetermined copper(II) contents. 4

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Literature Cited 1. Uytterhoeven, J. B.; Christner, L. G.; Hall, W. Κ., J. Phys. Chem., (1965), 69, 2117. 2. Ward, J. W., J. Catal., (1967), 9, 225. 3. Cattanach, J.; Wu, E. L.; Venuto, P. Β., J. Catal., (1968), 11, 342. 4. Kerr, G. T., J. Catal., (1969), 15, 200. 5. Lai, P. P.; Rees, L. V. C., J. Chem. Soc., Faraday Trans. I, (1976), 72, 1809.



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6. Maes, A.; Cremers, Α., J. Chem. Soc., Faraday Trans, I, (1975) 71, 265. 7. Lussier, R. J . ; Magee, J. S., Jr.; Albers, E. W., U.S. Patent 3.929,621, (Dec. 30, 1975); assigned to W. R. Grace & Co. 8. Dolbear, G. E.; Magee, J.S., U.S. Patent 3.835,032, Sept. 10, 1974); assigned to W. R. Grace & Co. 9. Herman, R. G.; Bulko, J. B., 14th Middle Atlantic Regional Meeting of the American Chemical Society, King of Prussia, PA, April 23-25, 1980, Abstr. No. CSC-9. 10. Eulenberger, G. R.; Shoemaker, D. P.; Keil, J. G., J. Phys. Chem., (1967), 71, 1812. 11. Baur, W. Η., Am. Mineralogist, (1964), 49, 697. 12. Sherry, H. S., J. Phys. Chem., (1966), 70, 1158. 13. Sherry, H. S., J. Colloid Interface Sci., (1968), 28, 288. 14. Barrer, R. M.; Davies, J. A.; Rees, L. V. C., J. Inorg. Nucl. Chem., (1968), 30, 3333. 15. Breck, D. W., "Zeolite Molecular Sieves", Wiley, New York, 1974. 16. Herman, R. G.; Flentge, D. R., J. Phys. Chem., (1978), 82, 720. 17. Lai, P. P.; Rees, L. V. C., J. Chem. Soc., Faraday Trans. I, (1976), 72, 1809. 18. Nightingale, E. R., Jr., J. Phys. Chem., (1959), 63, 1381. 19. Chu, P.; Dwyer, F. G., J. Catal., (1980), 61, 454. RECEIVED

April 24, 1980.


Adsorption and Ion Exchange with Synthetic Zeolites - American

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