Processes for Demetalization of Fluid Cracking Catalysts - American

Chapter 14

Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on September 2, 2015 | http://pubs.acs.org Publication Date: September 12, 1988 | doi: 10.1021/bk-1988-0375.ch014

Processes for Demetalization of Fluid Cracking Catalysts 1

2

2

F. J. Elvin , J.-E. Otterstedt , and J. Sterte 1

ChemCat Corporation, P.O. Box 29866, New Orleans, LA 70189 Department of Engineering Chemistry 1, Chalmers University of Technology, Fack, S-412 96, Göteborg, Sweden 2

Three processes, Demet III, Demet X and New Demet, for demetalization of metal poisoned octacat fluid cracking catalysts were investigated. These processes removed a significant part of the V (30-40%) from the catalyst. The New Demet and Demet III were very effective in removing Ni (88% and 80%, respectively) while practically no Ni could be removed by Demet X. The Demet procedures also proved effective in removing other contaminants like Fe and Cu. All Demet methods resulted in increased cracking activities as determined by the micro activity test. The conversions increased from 65% for the untreated catalyst to 76-78% for samples treated according to the different Demet procedures. The increase in activity was accompanied by a corresponding increase in gasoline yield of 5.0-6.5%. T h e c o n t r o l o f t h e a c t i v i t y a n d s e l e c t i v i t y o f c r a c k i n g c a t a l y s t is t h e k e y t o optimum yields and profitability. Currently, refineries employ two different methods o f c o n t r o l : the addition of fresh catalyst and the addition of good quality equilibrium catalyst. Onsite F C C U catalyst demetalization, called D e m e t , is a t h i r d a l t e r n a t i v e w h i c h w a s o r i g i n a l l y d e v e l o p e d by A R C O a n d t h e n i m p r o v e d b y C h e m C a t C o r p o r a t i o n w o r k e r s (1). T h e D e m e t p r o c e d u r e s are used to r e m o v e a c t i v e m e t a l c o n t a m i n a n t s f r o m t h e surface o f e q u i l i b r i u m c a t a l y s t s , thus i m p r o v i n g c a t a l y s t a c t i v i t y a n d s e l e c t i v i t y . D e m e t procedures are applicable to a l l types o f amorphous and z e o l i t i c catalysts. U n d e r F C C U o p e r a t i n g c o n d i t i o n s , a l m o s t 100% o f the m e t a l c o n t a m i n a n t s in t h e feed (such as n i c k e l , v a n a d i u m , i r o n a n d copper porphyrins) a r e d e c o m p o s e d a n d d e p o s i t e d o n t h e c a t a l y s t (2). T h e m o s t h a r m f u l o f t h e s e contaminants are vanadium and nickel. T h e deleterious effect of the deposited vanadium on catalyst performance and the manner i n which vanadium is deposited on the c r a c k i n g catalyst differ from those of nickel. T h e effect of vanadium on the catalyst performance is primarily a decrease in catalyst a c t i v i t y w h i l e the major e f f e c t o f n i c k e l is a s e l e c t i v i t y change r e f l e c t e d i n i n c r e a s e d c o k e a n d gas y i e l d s (3). R e c e n t l a b o r a t o r y studies (3-6) show t h a t nickel distributes homogeneously over the catalyst surface while vanadium preferentially deposits on and reacts destructively w i t h the z e o l i t e . A m e c h a n i s m for v a n a d i u m poisoning i n v o l v i n g v o l a t i l e v a n a d i c a c i d as t h e

0097-6156/88/0375-0229$06.00/0 ° 1988 American Chemical Society

In Fluid Catalytic Cracking; Occelli, M.; ACS Symposium Series; American Chemical Society: Washington, DC, 1988.

FLUID CATALYTIC CRACKING: R O L E IN M O D E R N REFINING

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p o i s o n p r e c u r s o r w a s p r o p o s e d b y W o r m s b e c h e r e t a l . (7). A c c o r d i n g t o t h i s m e c h a n i s m , v a n a d i c a c i d is f o r m e d u n d e r F C C r e g e n e r a t o r c o n d i t i o n s b y t h e reaction:


V 2 O 5

(s)

+

3

H

2

0

2

H 3 V O 4

(v)

Since vanadic a c i d is a strong a c i d analogous to phosphoric a c i d i t c a n destroy the z e o l i t e by h y d r o l y s i s of t h e z e o l i t e S 1 O 2 / A I 2 O 3 f r a m e w o r k . R e c e n t l y O c c e l l i (8) h a s s h o w n t h a t v a n a d i u m d e p o s i t e d o n c a t a l y s t p a r t i c l e s i s a b l e t o m i g r a t e t o p a r t i c l e s o f a m e t a l scavenger (sepiolite), w h i c h i n i t i a l l y does n o t contain vanadium, where it can form stable vanadates. Stability together w i t h r a m a n s p e c t r a of ( h y d r o t h e r m a l l y aged) V - l o a d e d F C C w e r e used to show t h a t a n a c i d l i k e H 4 V 2 O 7 w a s m o r e l i k e l y t o b e t h e v o l a t i l e s p e c i e f o r m e d (8). In m o s t l a b o r a t o r y d e a c t i v a t i o n s t u d i e s t h e c a t a l y s t is i m p r e g n a t e d w i t h v a n a d i u m c o m p o u n d s a n d then t r e a t e d for many hours (5-10 hrs.) a t high t e m p e r a t u r e s (1300°-1500°F) w i t h high s t e a m p a r t i a l pressures. A s t h e h y d r o l y s i s o f V 2 O 5 i n c r e a s e s r a p i d l y w i t h i n c r e a s i n g t e m p e r a t u r e as w e l l a s w i t h i n c r e a s i n g w a t e r p a r t i a l p r e s s u r e (9), t h e s e c o n d i t i o n s p r o m o t e t h e formation of an acid which permanently destroys the catalyst. However, the v a n a d i u m c h e m i s t r y is d i f f e r e n t i n a c o m m e r c i a l F C C U i n w h i c h the r e g e n e r a t o r t e m p e r a t u r e u s u a l l y is i n t h e r a n g e 1250-1400°F, t h e s t e a m p a r t i a l p r e s s u r e i n t h e r a n g e 0.1 - 0 . 4 a t m a n d i n w h i c h t h e t o t a l r e s i d e n c e t i m e for the c a t a l y s t is widely d i s t r i b u t e d as c a t a l y s t is continuously added to and withdrawn from the unit. A t these conditions, part of the vanadium induced d e a c t i v a t i o n is t e m p o r a r y a n d c a n be r e v e r s e d by t h e D e m e t p r o c e d u r e s (ΙΟ Ι 1). T h i s paper gives a n e x a m p l e of t h e response of one e q u i l i b r i u m c a t a l y s t t o the three basic D e m e t procedures and to modified versions of these p r o c e d u r e s . T h e c a t a l y s t s a r e e v a l u a t e d by e l e m e n t a l analysis a n d by t h e i r c r a c k i n g p e r f o r m a n c e , as d e t e r m i n e d by the m i c r o a c t i v i t y test ( M A T ) . Experimental Catalyst. T h e c a t a l y s t used i n this study is a n e q u i l i b r i u m O c t a c a t fluid cracking catalyst from a US refinery. The metal analysis of this catalyst and i t s M A T c r a c k i n g p e r f o r m a n c e a r e g i v e n i n T a b l e I a n d T a b l e II, r e s p e c t i v e l y . G a s phase t r e a t m e n t . T h e g a s p h a s e t r e a t m e n t i n t h e D e m e t III p r o c e d u r e w a s s i m i l a r t o t h a t d e s c r i b e d b y B u r k e t a l . (12). T h e c a t a l y s t w a s f i r s t sulfided a t 720°C for 4 hrs. i n a f l u i d i z e d bed r e a c t o r . A f t e r c o o l i n g to 340°C under a flow of nitrogen, the c a t a l y s t was o x i d i z e d w i t h air at this t e m p e r a t u r e f o r 30 m i n . In t h e N e w D e m e t p r o c e d u r e , t h e c a t a l y s t w a s f i r s t c a l c i n e d i n a i r a t 730°C for 4 hrs. i n a f l u i d i z e d bed r e a c t o r . T h e c a t a l y s t was then sulfided at 730°C f o r 2 h r s . A f t e r c o o l i n g d o w n t h e c a t a l y s t t o 320°C under a flow of nitrogen, it was chlorinated at this temperature for 1 hr. T h e gas phase t r e a t m e n t i n the D e m e t X procedure s i m p l y consisted of c a l c i n i n g the c a t a l y s t i n a i r i n a f l u i d i z e d bed r e a c t o r at 720°C for 4 hrs. Washing procedures. T h e aqueous phase t r e a t m e n t s used for t h e different s a m p l e s d i s c u s s e d i n t h i s p a p e r a r e s c h e m a t i c a l l y s h o w n i n f i g u r e s 1-3. T h e D e m e t III w a s h c o n s i s t e d o f t w o r e d u c t i v e w a s h e s f o l l o w e d b y t w o o x i d a t i v e w a s h e s . In t h e r e d u c t i v e w a s h , a p p r o x i m a t e l y 40 g . o f t r e a t e d c a t a l y s t w a s dispersed i n 250 m l of d e i o n i z e d w a t e r . T h e t e m p e r a t u r e was a d j u s t e d t o 7 0 ° C a n d S O 2 w a s b u b b l e d t h r o u g h t h e d i s p e r s i o n f o r 5 m i n . In t h e o x i d a t i v e wash, t h e c a t a l y s t was f i r s t dispersed i n 250 m l of d e i o n i z e d w a t e r


14. ELVIN ET AL.

Demetalization of Fluid Cracking Catalysts

231


a n d t h e t e m p e r a t u r e w a s a d j u s t e d t o 7 0 ° C . T o t h i s d i s p e r s i o n , 20 a n d 5 m l o f H 2 O 2 (35%) w a s a d d e d i n t h e f i r s t a n d s e c o n d o x i d a t i v e w a s h , r e s p e c t i v e l y . The c a t a l y s t was t r e a t e d w i t h these solutions for 3 m i n . T h e R E - e x c h a n g e was c a r r i e d out by t r e a t i n g the c a t a l y s t at 90°C for 1 hr. w i t h a r a r e e a r t h c h l o r i d e s o l u t i o n h a v i n g a c o n c e n t r a t i o n o f 110 g R E 2 O 3 / I . T h e N H ^ - e x c h a n g e was p e r f o r m e d by t r e a t i n g the c a t a l y s t a t 9 0 ° C for 1 h r . w i t h a s o l u t i o n c o n t a i n i n g 130 g/1 ( N H ^ S O ^ . A f t e r e a c h w a s h or i o n e x c h a n g e , the c a t a l y s t was s e p a r a t e d f r o m the s o l u t i o n by f i l t r a t i o n . Elemental analysis. E l e m e n t a l analysis was performed w i t h a t o m i c absorption spectroscopy (AAS). Solid samples were first solubilized according t o t h e p r o c e d u r e d e s c r i b e d b y M a r c h a n d M e y e r s (13). Catalytic cracking. The c r a c k i n g studies were c a r r i e d out using a fixed bed reactor constructed according to A S T M method D 3907-80 " M i c r o A c t i v i t y T e s t f o r F l u i d C r a c k i n g C a t a l y s t s " ( M A T ) . In t h i s m e t h o d a k n o w n a m o u n t o f o i l is fed to a bed of c r a c k i n g c a t a l y s t . T h e gas and l i q u i d p r o d u c t s a r e c o l l e c t e d and a n a l y z e d by gas c h r o m a t o g r a p h y . T h e b o i l i n g p o i n t r a n g e of t h e l i q u i d p r o d u c t s is d e t e r m i n e d by s i m u l a t e d d i s t i l l a t i o n . T h e a c t i v i t y of t h e c a t a l y s t i n c a t a l y t i c c r a c k i n g is d e f i n e d as t h e w e i g h t - % of t h e f e e d t h a t is c o n v e r t e d i n t o c o k e , gas and gasoline. T h e gasoline f r a c t i o n is t h e p o r t i o n of the p r o d u c t b o i l i n g b e t w e e n 36° and 216°C. T h e light c y c l e o i l ( L C O ) is not i n c l u d e d i n t h e c o n v e r s i o n b u t is c a l c u l a t e d f r o m t h e s i m u l a t e d d i s t i l l a t i o n as t h e f r a c t i o n b o i l i n g b e t w e e n 216° and 3 4 4 ° C . T h e c r a c k i n g tests w e r e p e r f o r m e d using a hydroprocessed m i x t u r e of N o r t h S e a and A r a b i a n light H V G O , and a reactor temperature of 500°C. A m a t e r i a l r e c o v e r y b a l a n c e was c a l c u l a t e d for e a c h r u n . A l l tests w i t h a r e c o v e r y of less than 9 7 % w e r e d i s c a r d e d . F o r e a c h sample, d u p l i c a t e runs w e r e made in order to ensure reproducible results. Results and Discussion Metals removal. T h e r e s u l t s of t h e m e t a l s r e m o v a l for s o m e r e l e v a n t s a m p l e s a r e s h o w n i n T a b l e I. A s s e e n , a l l D e m e t p r o c e d u r e s r e m o v e d a significant part of the v a n a d i u m (30-40%) f r o m the c a t a l y s t surface. F o r the r e m o v a l o f N i , b o t h t h e N e w D e m e t a n d D e m e t III p r o c e d u r e w a s v e r y e f f e c t i v e . T h e N e w D e m e t p r o c e s s r e m o v e d 8 8 % of t h e n i c k e l w h i l e t h e c o r r e s p o n d i n g v a l u e f o r D e m e t III w a s 8 0 % . H o w e v e r , n i c k e l c o u l d n o t b e r e m o v e d by t h e D e m e t X p r o c e d u r e . W h i l e t h e gas phase t r e a t m e n t i n t h e

T A B L E I.

Catalyst

R e s u l t s of m e t a l s analysis of d e m e t a l i z e d

V

designation

(ppm)

samples

Ni

Fe

Sb

Cu

Na

(ppm)

(ppm)

(ppm)

(ppm)

(ppm!

45.8

3954

Oct-0

3667

1477

4966

823

A2a

2199

170

1840

179

19.8

3039

Bla

2348

287

3050

296

29.6

3436

C2c

2330

1337

5380

395

37.8

3118



232


D e m e t X procedure s i m p l y consists of an o x i d a t i o n at e l e v a t e d t e m p e r a t u r e , b o t h t h e N e w D e m e t a n d t h e D e m e t III p r o c e s s h a s a s u l f i d i n g s t e p w h i c h t r a n s f o r m s t h e m e t a l o x i d e s t o i n s o l u b l e s u l f i d e s . In D e m e t III t h e s u l f i d i n g s t e p i s f o l l o w e d by a p a r t i a l o x i d a t i o n s t e p . T h i s o x i d a t i o n i s c a r e f u l l y c o n t r o l l e d to p r o d u c e m e t a l s u l f a t e s and sulfides w h i c h c a n be d i r e c t l y r e m o v e d by w a s h i n g or be t r a n s f e r r e d i n t o s o l u b l e c o m p o u n d s by t h e r e d u c t i v e a n d o x i d a t i v e w a s h e s u s e d i n t h i s p r o c e d u r e . In t h e N e w D e m e t p r o c e s s t h e s u l f i d i n g s t e p is f o l l o w e d by c h l o r i n a t i o n w h i c h results i n a t r a n s f o r m a t i o n of the sulfides into washable chlorides. Since vanadium chlorides are volatile, m o s t o f t h e v a n a d i u m r e m o v a l u s i n g t h i s p r o c e d u r e o c c u r s i n t h e g a s p h a s e . In t h e D e m e t X p r o c e d u r e , t h e v a n a d i u m o x i d e s f o r m e d a r e w a t e r s o l u b l e or c a n b e t r a n s f o r m e d i n t o w a t e r s o l u b l e f o r m s b y a q u e o u s t r e a t m e n t s . In c o n t r a s t the n i c k e l oxides are insoluble in water. T h e t e n d e n c y for the d i f f e r e n t p r o c e d u r e s to r e m o v e i r o n and copper was s i m i l a r to t h a t for n i c k e l r e m o v a l i n t h e sense t h a t these m e t a l s w e r e r e m o v e d b y t h e N e w D e m e t a n d t h e D e m e t III p r o c e s s e s b u t n o t b y D e m e t X . T h e t o t a l r e m o v a l o f t h e s e m e t a l s w a s l o w e r t h a n t h a t o f n i c k e l . In t h e c a s e o f i r o n , t h i s c o u l d b e e x p l a i n e d b y t h e f a c t t h a t s o m e o f t h e i r o n is i n c o r p o r a t e d i n t o t h e c l a y m a t r i x a n d t h e r e f o r e p r o b a b l y m o r e d i f f i c u l t t o r e m o v e by t h e s e t r e a t m e n t s . T h e u n t r e a t e d c a t a l y s t c o n t a i n e d about 800 p p m a n t i m o n y w h i c h has been added i n the c o m m e r c i a l c r a c k i n g o p e r a t i o n to p a s s i v a t e N i . T h e D e m e t processes tested r e m o v e d a s i g n i f i c a n t part of a n t i m o n y f r o m the c a t a l y s t . T h e e f f i c i e n c y of the d i f f e r e n t p r o c e d u r e s for a n t i m o n y r e m o v a l is s i m i l a r to t h a t for v a n a d i u m r e m o v a l . T h i s m a y s e e m s o m e w h a t s t r a n g e as t h e a n t i m o n y associates w i t h the n i c k e l . T h e a n t i m o n y oxides f o r m e d upon c a l c i n a t i o n in the D e m e t X procedure are, however, slightly soluble in water. T h e D e m e t procedures also r e m o v e a l a r g e f r a c t i o n of the s o d i u m f r o m t h e c a t a l y s t s . T h i s m a y n o t b e c l e a r l y s e e n i n t h e c a s e d i s c u s s e d h e r e as t h e s t a r t i n g c a t a l y s t has a v e r y l o w s o d i u m c o n t e n t . F o r other e q u i l i b r i u m c a t a l y s t s , i n v e s t i g a t e d by us, the s o d i u m r e m o v a l has been i n the 2 0 - 5 0 % r a n g e . It s h o u l d a l s o b e n o t e d t h a t t h e v a l u e s g i v e n i n T a b l e I r e p r e s e n t t h e s o d i u m c o n t e n t p r i o r to i o n e x c h a n g e . U p o n e x c h a n g e w i t h a m m o n i u m or r a r e e a r t h , t h e s o d i u m c o n t e n t is f u r t h e r r e d u c e d . In a d d i t i o n t o m e t a l s , t h e D e m e t procedures remove minor fractions of a l u m i n u m and rare e a r t h metals from the c a t a l y s t . The A l dissolution in the N e w D e m e t process corresponds to a decrease i n a l u m i n a c o n t e n t of 0.01-0.1 w t % , depending on the w a s h i n g p r o c e d u r e , w h i l e t h e c o r r e s p o n d i n g r a n g e f o r t h e D e m e t III p r o c e s s i s 0 . 0 5 - 0 . 3 w t % . M o s t of the A l is dissolved i n the low p H washes, i.e. the f i r s t w a t e r w a s h i n t h e N e w D e m e t p r o c e s s a n d t h e S 0 2 ~ w a s h e s i n t h e D e m e t III. Cracking performance. M i c r o a c t i v i t y test results for the d i f f e r e n t p r e p a r a t i o n s a r e g i v e n i n T a b l e II. V a r i a n t s o f a l l t h r e e b a s i c D e m e t p r o c e d u r e s (see F i g . 1-3) c a n b e u s e d t o i m p r o v e t h e p e r f o r m a n c e o f t h i s equilibrium catalyst. The most successful N e w D e m e t preparation, A 4 , showed a M A T c o n v e r s i o n of 7 7 . 1 % c o m p a r e d to 6 5 . 2 % for the u n t r e a t e d e q u i l i b r i u m c a t a l y s t . T h i s i n c r e a s e i n c o n v e r s i o n was a c c o m p a n i e d by an i n c r e a s e i n gasoline y i e l d f r o m 46.8 t o 5 2 . 3 % a n d a d e c r e a s e i n c o k e y i e l d f r o m 4.5 t o 4 . 3 % . T h e s e r e s u l t s w e r e a c h i e v e d by s u b j e c t i n g t h e c a t a l y s t to a series of t r e a t m e n t s a f t e r the b a s i c gas phase r e a c t i o n s , i n v o l v i n g o x i d a t i v e and r e d u c t i v e washes, a n d i o n e x c h a n g e w i t h N H ^ a n d R E (see F i g . 1). E a c h o f t h e s e t r e a t m e n t s resulted i n a successive i m p r o v e m e n t of c a t a l y s t p e r f o r m a n c e . In t h e D e m e t III s e r i e s , s a m p l e B 3 g a v e t h e b e s t r e s u l t s , s h o w i n g a M A T c o n v e r s i o n o f 7 6 . 2 % . T h e g a s o l i n e y i e l d o f t h i s s a m p l e w a s 5 3 . 2 % , up f r o m 4 7 . 0 % i n t h e u n t r e a t e d s a m p l e . In t h e D e m e t III s e r i e s a l l s a m p l e s e x c e p t B i b +



14. ELVIN ET AL.


T a b l e II.

M A T - c r a c k i n g results for d e m e t a l i z e d samples

catalyst designation

conv (wt%)

octacat 0

65.2

Ala

233

LCO (wt%)

coke (wt%)

gas (wt%)

46.8

4.5

13.9

16.5

70.0

48.7

4.3

17.0

14.6

Alb

71.5

49.8

5.0

16.8

14.9

Ale

67.6

47.2

4.0

16.4

15.2

Aid

66.3

46.4

4.2

15.7

16.3

A2a

72.2

50.7

3.5

18.0

13.7

A2b

70.4

47.5

5.2

17.7

14.0

A2c

69.7

49.0

4.1

16.7

14.2

A3a

71.9

50.1

3.8

18.0

14.8

A3b

75.2

50.3

4.4

20.5

12.5

A3c

70.6

47.6

4.7

18.2

14.5

gasoline (wt%)

A4

77.1

52.3

4.3

20.6

12.0

Bla

66.5

45.0

5.2

16.3

17.1

Bib

53.8

37.8

3.9

12.2

16.9

B2a

73.0

51.2

4.4

17.4

14.0

B2b

70.5

48.0

5.0

17.4

14.6

B3

76.2

53.2

4.2

18.8

13.4

Cl

60.3

41.4

4.8

14.0

17.4

C2a

69.1

46.2

5.1

17.8

15.3

C2b

69.1

47.2

4.3

17.7

15.9

C2c

70.8

49.2

4.1

16.9

14.0

C3a

70.6

46.7

5.2

18.7

14.6

C3b

71.4

48.6

5.3

17.5

14.3

C3c

72.9

51.3

4.1

17.5

12.7

C4

76.0

51.7

4.7

19.8

11.5




234

NEW DEMET

F i g u r e 1.

S c h e m a t i c representation of modifications used in the gaseous

(top level) and in the aqueous phase treatments in the New

Demet

preparations.


14. ELVIN ET AL.


235


DEMET HI

F i g u r e 2.

S c h e m a t i c r e p r e s e n t a t i o n o f m o d i f i c a t i o n s used i n t h e gaseous

( t o p l e v e l ) a n d a q u e o u s p h a s e t r e a t m e n t s i n t h e D e m e t III p r e p a r a t i o n s .

DEMET X H20-wash

REexch.

F i g u r e 3.

S c h e m a t i c r e p r e s e n t a t i o n of m o d i f i c a t i o n s used i n t h e aqueous

phase t r e a t m e n t s i n t h e D e m e t X preparations.



236

showed an i m p r o v e d c r a c k i n g performance r e l a t i v e to the untreated equilibrium c a t a l y s t . The t r e a t m e n t of sample B i b differs from the t r e a t m e n t s of t h e other s a m p l e s i n t h a t H 2 was used t o g e t h e r w i t h H 2 S i n t h e s u l f i d a t i o n step.The addition of H 2 obviously had a negative effect on catalyst performance. In t h e D e m e t X s e r i e s , t h e m o s t s u c c e s s f u l r e s u l t s w e r e o b t a i n e d f o r preparation C 4 . T h e M A T conversion for this sample was 76.0% and the gasoline yield 51.7%.


Conclusion F r o m t h e d a t a g i v e n i n T a b l e I a n d T a b l e II, i t i s c l e a r t h a t , f o r t h i s p a r t i c u l a r e q u i l i b r i u m c a t a l y s t , a l l the D e m e t processes i n v e s t i g a t e d w e r e e f f e c t i v e in r e m o v i n g m e t a l poisons from the c a t a l y s t surface and restoring a significant part of its original c r a c k i n g a c t i v i t y . The catalyst responded i n a similar manner to a l l three processes, showing an increase in conversion of more than 10 M A T n u m b e r s a c c o m p a n i e d b y a n i n c r e a s e i n g a s o l i n e y i e l d o f 5 - 6 . 5 M A T numbers. D u e to the s i m i l a r nature of the processes, it was possible to design a f l e x i b l e D e m e t unit w h i c h c a n be used, w i t h m i n o r m o d i f i c a t i o n s , for a l l the processes. The design of this unit and its incorporation into the flowsheet of t h e r e f i n e r y w a s d i s c u s s e d i n a p r e v i o u s p a p e r (1). T h i s p a p e r a l s o d i s c u s s e d t h e c o m m e r c i a l benefits of using D e m e t processing under d i f f e r e n t o p e r a t i o n c o n d i t i o n s (1).

Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

Elvin, F. J., Otterstedt, J-E., and Sterte, J., Paper no. AM-86-41, NPRA Annual Meeting, Los Angeles, California, March 1986. Skinnerm, D. Α., I.& E. C., 1959, 44(5), 1159. Järås, S., Appl. Cat., 1982, 2, 207. Nishimura, Y., Masuda, T., Sato, G., and Egashira, S., Preprints, ACS Div. Petr. Chem., 1983, 28, 707. Occelli, M. L., Psaras, D., and Suib, S. L., J. Catal., 1985, 96, 363. Woolery, G. L., Chin, Α. Α., Kirker, G. W., and Huss, Α., Preprints, ACS Div. Petr. Chem., 1987, 32, 663. Wormsbecher, R. F., Peters, A. W., and Maselli, J. M., J. Catal., 1986, 100, 130. Occelli, M. L., Preprints, ACS Div. Petr. Chem., 1987, 32, 658. Yannopoulos, L. N., J. Phys. Chem., 1968, 72, 3293. Elvin, F., Paper no. AM-87-44, NPRA Annual Meeting, San Antonio, Texas, March 1987. Elvin, F., Oil & GasJ.,1987, 85(9), 42. Burk, E. H., Erickson, H., and Anderson, A. D., U.S. Patent, 3,122,510, 1978. Marsh, W. W., and Myers, G., Anal. Chim. Acta, 1968, 43, 511.

RECEIVED March 30,1988


Processes for Demetalization of Fluid Cracking Catalysts - American

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