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Downloaded by UNIV OF CALIFORNIA SAN DIEGO on December 29, 2015 | http://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0020.ch002

Catalyst Effects on Yields and Product Properties in Hydrocracking R. F. SULLIVAN and J. A. MEYER Chevron Research Co., Richmond, Calif. 94802

The flexibility o f h y d r o c r a c k i n g as a p r o c e s s f o r refining p e t r o l e u m has r e s u l t e d in its phenomenal growth d u r i n g the p a s t 15 y e a r s . F e e d s t o c k s t h a t can be c o n v e r t e d t o lower boiling o r more d e s i r a b l e p r o d u c t s range from r e s i d u a t o n a p h t h a s . Products i n c l u d e such w i d e l y d i v e r s e m a t e r i a l s as g a s o l i n e , kerosene, middle distillates, lubricating oils, fuel oils, and various chemicals ( 1 , 2 ) . Commercial h y d r o c r a c k i n g is c a r r i e d out in a single s t a g e o r in two o r more s t a g e s in s e r i e s . Numerous h y d r o c r a c k i n g c a t a l y s t s have been d e v e l o p e d ; and the more r e c e n t o f t h e s e have e x c e p t i o n a l l y long lives, even at s e v e r e o p e r a t i n g c o n d i t i o n s . The c h o i c e of the c a t a l y s t and o f the particular p r o c e s s i n g scheme will depend on many f a c t o r s such as feed p r o p e r t i e s , p r o p e r t i e s o f the d e s i r e d p r o d u c t s , s i z e o f the h y d r o cracking unit, availability of other processing facilities, and v a r i o u s o t h e r economic c o n s i d e r a t i o n s . In t h i s p a p e r , we will examine s e v e r a l h y d r o cracking catalysts of varying acidities and hydrogenation-dehydrogenation activities and show differences in p r o d u c t distributions and p r o d u c t p r o p e r ties o b t a i n e d from two r e p r e s e n t a t i v e domestic f e e d s t o c k s in the second s t a g e o f a t w o - s t a g e h y d r o cracking process. I n such a p r o c e s s , the f e e d t o the second s t a g e has been h y d r o f i n e d in the first stage i n o r d e r t o remove most o f the i m p u r i t i e s such as n i t r o g e n and s u l f u r . In particular, we will emphasize (1) total liquid yield, i n c l u d i n g pentanes and all o f the h i g h e r boiling p r o d u c t , and (2) octane number o f the l i g h t p r o d u c t c o n s i s t i n g m a i n l y o f m o l e c u l e s w i t h carbon numbers o f 5 and 6, r e f e r r e d t o as C - l 8 0 ° F p r o d u c t . H i g h C5+ 5

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In Hydrocracking and Hydrotreating; Ward, John W., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1975.

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l i q u i d y i e l d s are d e s i r a b l e i n s i t u a t i o n s i n which butanes and propane are i n o v e r s u p p l y o r o f l o w e r v a l u e than the l i q u i d products. A h i g h o c t a n e number i n t h e C5-l80°F product i s p a r t i c u l a r l y d e s i r a b l e because i t i s more d i f f i c u l t t o u p g r a d e t h i s l o w b o i l i n g f r a c t i o n t h a n t h e h i g h e r b o i l i n g n a p h t h a s , w h i c h c a n be u p g r a d e d r e l a t i v e l y e a s i l y by c a t a l y t i c r e f o r m i n g .


Background Most h y d r o c r a c k i n g c a t a l y s t s o f c o m m e r c i a l i n t e r est are dual f u n c t i o n a l i n nature, c o n s i s t i n g o f both a h y d r o g e n a t i o n - d e h y d r o g e n a t i o n component and an a c i d i c support. The r e a c t i o n s c a t a l y z e d b y t h e i n d i v i d u a l components a r e q u i t e d i f f e r e n t . In specific catalysts, t h e r e l a t i v e s t r e n g t h s o f t h e two components can be varied. The r e a c t i o n s o c c u r r i n g and t h e p r o d u c t s formed depend c r i t i c a l l y upon t h e b a l a n c e between t h e s e two c o m p o n e n t s . The a c i d f u n c t i o n o f t h e c a t a l y s t i s s u p p l i e d b y the support. Among t h e s u p p o r t s m e n t i o n e d i n t h e l i t e r a t u r e are s i l i c a - a l u m i n a , s i l i c a - z i r c o n i a , s i l i c a magnesia, alumina-boria, s i l i c a - t i t a n i a , a c i d - t r e a t e d c l a y s , a c i d i c m e t a l p h o s p h a t e s , a l u m i n a , and o t h e r such s o l i d a c i d s . The a c i d i c p r o p e r t i e s o f t h e s e amorphous c a t a l y s t s c a n be f u r t h e r a c t i v a t e d by t h e a d d i t i o n o f s m a l l p r o p o r t i o n s o f a c i d i c h a l i d e s s u c h as HF, B F , S i F i t , and t h e l i k e (3.). Z e o l i t e s s u c h as t h e f a u j a s i t e s and m o r d e n i t e s a r e a l s o i m p o r t a n t s u p p o r t s for hydrocracking c a t a l y s t s (2). The h y d r o g e n a t i o n - d e h y d r o g e n a t i o n c o m p o n e n t i s a m e t a l s u c h as c o b a l t , n i c k e l , t u n g s t e n , v a n a d i u m , molybdenum, p l a t i n u m . o r p a l l a d i u m , o r a c o m b i n a t i o n o f metals. The n o n - n o b l e m e t a l s a r e u s u a l l y p r e s u l f i d e d a l t h o u g h i t has been s u g g e s t e d t h a t the a c t u a l h y d r o g é n a t i o n a c t i v i t y f o r the s u l f i d e d c a t a l y s t s e x i s t s i n t r a n s i t o r y m e t a l l i c r e g i o n s on t h e s e c a t a l y s t s (h). The s u l f i d e d m e t a l s a r e g e n e r a l l y r e p o r t e d t o b e l e s s a c t i v e f o r h y d r o g é n a t i o n than the noble metal c a t a l y s t s (5.). The r e l a t i o n s h i p b e t w e e n t h e t w o c a t a l y t i c c o m ponents i s q u i t e complex. I n t e r a c t i o n s between the s u p p o r t and t h e h y d r o g é n a t i o n component c a n a l t e r t h i s relationship. F o r e x a m p l e , L a r s o n et- a l . (6) s h o w e d t h a t , w i t h p l a t i n u m on s i l i c a - a l u m i n a , a s e l e c t i v e a d s o r p t i o n o f p l a t i n u m by a c i d s i t e s c a u s e s a r e d u c t i o n in catalyst acidity. S i m i l a r l y , n i c k e l reacts w i t h the a c i d s i t e s on s i l i c a - a l u m i n a f o r m i n g n i c k e l s a l t s o f the s i l i c a - a l u m i n a a c i d s i t e s . I t has been s u g g e s t e d (7) t h a t one o f t h e e f f e c t s o f s u l f i d i n g a n i c k e l o n 3



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s i l i c a - a l u m i n a c a t a l y s t i s that hydrogen s u l f i d e r e a c t s w i t h t h e s e s a l t s and r e g e n e r a t e s t h e o r i g i n a l s t r o n g a c i d s i t e s of the s i l i c a - a l u m i n a . I n t h e r e a c t i o n s o f t h e many c o m p o n e n t m i x t u r e s t h a t make up m o s t c o m m e r c i a l f e e d s t o c k s , t h e r e l a t i o n s h i p b e t w e e n t h e t w o c a t a l y t i c c o m p o n e n t s may be f u r t h e r a l t e r e d by p r e f e r e n t i a l a d s o r p t i o n o f c e r t a i n h y d r o c a r b o n r e a c t a n t s o n c a t a l y t i c s i t e s ( £0 . For example, p o l y c y c l i c a r o m a t i c s have a h i g h l y v a r i a b l e e f f e c t d e p e n d e n t o n t h e t y p e a n d amount a s w e l l a s c a t a l y s t and r e a c t i o n c o n d i t i o n s . Catalyst poisons s u c h a s s u l f u r , n i t r o g e n , a n d o x y g e n may a f f e c t either or b o t h c a t a l y s t components ( £ ) . The l i t e r a t u r e o n t h e h y d r o c r a c k i n g o f v a r i o u s hydrocarbons i s summarized i n s e v e r a l r e v i e w a r t i c l e s (5310*11) and mechanisms o f h y d r o c a r b o n r e a c t i o n s presented. B e u t h e r a n d L a r s o n (h) a n d C o o n r a d t a n d c o w o r k e r s (9312,1331*0 compare t h e r e a c t i o n s o f n o b l e m e t a l c a t a l y s t s and the n o n - n o b l e m e t a l s u l f i d e s . C a t a l y s t s w i t h h i g h h y d r o g é n a t i o n a c t i v i t y s u c h as t h e noble metal c a t a l y s t s are reported to favor the format i o n o f h i g h e r b o i l i n g p r o d u c t s and minimum l i g h t hydrocarbon production. C a t a l y s t s w i t h low h y d r o g é n a t i o n a c t i v i t y r e l a t i v e to a c i d i t y y i e l d product with a higher r a t i o of branched paraffins to normal p a r a f f i n s and l e s s s a t u r a t i o n o f a r o m a t i c s . With the latter c a t a l y s t s , t h e naphtha p r o d u c t has a h i g h e r octane number. S c h u t z a n d W e i t k a m p (15.) show p r o d u c t d i s t r i b u t i o n s f o r t h e h y d r o c r a c k i n g o f dodecane on s e v e r a l n o b l e m e t a l s on z e o l i t e c a t a l y s t s . Product d i s t r i b u t i o n s are i n general s i m i l a r to those d i s t r i b u t i o n s p r e v i o u s l y r e p o r t e d f o r n o b l e m e t a l s on amorphous supports. T h e s e r e s u l t s show n o m a j o r u n e x p e c t e d e f f e c t o f t h e z e o l i t i c s u p p o r t ; d i f f e r e n c e s among t h e c a t a l y s t s t e s t e d a r e r e l a t e d t o changes i n h y d r o g é n a t i o n a b i l i t y or a c i d i t y . In o r d e r t o o b t a i n q u a n t i t a t i v e measurements o f h y d r o g é n a t i o n a c t i v i t y and a c i d i t y , v a r i o u s schemes are employed. F o r e x a m p l e , m e t a l s u r f a c e a r e a has been r e l a t e d t o h y d r o g é n a t i o n a c t i v i t y and the a d s o r p t i o n o f b a s e s s u c h a s p y r i d i n e a n d ammonia h a v e b e e n c o r r e l a t e d w i t h a c i d i t y (6). Some a u t h o r s h a v e u s e d c e r t a i n k e y r e a c t i o n s i n v o l v i n g p u r e compounds a s a n i n d i c a t i o n o f c a t a l y t i c p r o p e r t i e s (16). Each o f these methods i s u s e f u l ; h o w e v e r , b e c a u s e o f t h e complex interdependence of the c a t a l y t i c functions of the h y d r o c r a c k i n g c a t a l y s t s and changes i n t h e s e f u n c t i o n s w i t h c a t a l y s t a g i n g , r e s u l t s f r o m e a c h method must be interpreted with caution.



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C o o n r a d t a n d c o w o r k e r s (13_) u s e a n e m p i r i c a l h y d r o g é n a t i o n a c t i v i t y i n d e x b a s e d on t h e a r o m a t i o naphthene r a t i o i n the hydrocracked p r o d u c t . This a p p r o a c h does n o t p r o v i d e an i n d e p e n d e n t measure o f catalytic properties. However, i t has t h e a d v a n t a g e t h a t a c t i v i t i e s are measured under a c t u a l h y d r o c r a c k i n g c o n d i t i o n s ; and changes i n c a t a l y t i c p r o p e r t i e s w i t h c a t a l y t i c a g i n g can be o b s e r v e d . Most d i r e c t comparisons a v a i l a b l e i n the l i t e r a t u r e among c a t a l y s t s o f v a r y i n g h y d r o g e n a t i o n - t o a c i d i t y r a t i o s are f o r s i n g l e pass p r o c e s s i n g . Because o f t h e d i f f e r e n t r e a c t i v i t i e s o f t h e components o f comm e r c i a l feed m i x t u r e s , the s p e c i f i c molecules that r e a c t i n a s i n g l e pass w i l l depend s t r o n g l y upon t h e t o t a l conversion. I n o t h e r w o r d s , t h e most s t r o n g l y adsorbed s p e c i e s w i l l r e a c t p r e f e r e n t i a l l y ; and the r e s u l t i n g product d i s t r i b u t i o n w i l l r e f l e c t the propert i e s of these reacting molecules. As t h e c o n v e r s i o n i n c r e a s e s , the p r o p e r t i e s of the r e a c t i n g molecules and t h e r e f o r e the p r o d u c t w i l l change. A l s o , i f two c a t a l y s t s w i t h d i f f e r e n t p r o p e r t i e s are compared at constant conversion, the p a r t i c u l a r species that react i n t h e p r e s e n c e o f one c a t a l y s t w i l l n o t n e c e s s a r i l y b e t h e same s p e c i e s t h a t r e a c t p r e f e r e n t i a l l y u s i n g t h e other. I n t h i s p a p e r we c o m p a r e b e h a v i o r o f c a t a l y s t s i n extinction recycle hydrocracking. In such a p r o c e s s i n g scheme, a l l o f the feed i s u l t i m a t e l y c o n v e r t e d t o product b o i l i n g below a c e r t a i n p r e d e f i n e d temperature. The r e a c t i o n p a t h s o f i n d i v i d u a l f e e d c o m p o n e n t s may d i f f e r from c a t a l y s t t o c a t a l y s t . Product d i s t r i b u t i o n s and p r o p e r t i e s a r e examined t o d e t e r m i n e the g e n e r a l e f f e c t s o f changes i n c a t a l y t i c p r o p e r t i e s . Experimental Equipment. A l l o f the c a t a l y s t s were t e s t e d i n continuous flow, fixed-bed p i l o t plants equipped for b o t h l i q u i d and gas r e c y c l e o p e r a t i o n and c o n t i n u o u s d i s t i l l a t i o n of products. Hydrocarbons b o i l i n g above t h e d e s i r e d p r o d u c t end p o i n t were r e c y c l e d t o e x t i n c t i o n , t h a t i s , t o 100$ c o n v e r s i o n o f f r e s h f e e d . The p r o d u c t was c o o l e d a n d p a s s e d i n t o a h i g h p r e s s u r e phase s e p a r a t o r . H e r e , h y d r o g e n - r i c h r e c y c l e g a s was f l a s h e d from the h y d r o c a r b o n p r o d u c t and r e c y c l e d back to the r e a c t o r i n l e t . E l e c t r o l y t i c h y d r o g e n make-up was a d d e d o n demand t o m a i n t a i n c o n s t a n t s y s t e m pressure. The l i q u i d f r o m t h e h i g h p r e s s u r e s e p a r a t o r was d e p r e s s u r e d and f l a s h e d at a t m o s p h e r i c p r e s s u r e . The



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l i q u i d h y d r o c a r b o n p h a s e was f e d t o t h e f i r s t o f t w o c o n t i n u o u s d i s t i l l a t i o n columns f o r the p r o d u c t f r a c tionation. In the f i r s t column, the m a t e r i a l b o i l i n g a b o v e t h e d e s i r e d r e c y c l e c u t p o i n t was s e p a r a t e d f r o m the lower b o i l i n g product. The o v e r h e a d f r o m t h i s c o l u m n was c o m b i n e d w i t h t h e g a s e o u s p r o d u c t f r o m t h e low p r e s s u r e f l a s h and f e d t o the second column i n w h i c h t h e p e n t a n e s and l i g h t e r gases were s e p a r a t e d from the l i q u i d p r o d u c t . The g a s e o u s p r o d u c t f r o m t h i s d e p e n t a n i z e r was m e t e r e d a n d a n a l y z e d b y g a s chromatography. L i q u i d p r o d u c t was d i s t i l l e d b a t c h w i s e f o r d e t e r m i n a t i o n o f l i q u i d y i e l d s and p r o d u c t p r o p e r t i e s . In the batch d i s t i l l a t i o n , the f i r s t l i q u i d product c u t was made a t l 8 0 ° F ( t r u e b o i l i n g p o i n t ) . Isopentane and n - p e n t a n e were added back t o t h i s d i s t i l l a t i o n c u t i n t h e amount m e a s u r e d i n t h e g a s e o u s p r o d u c t . The r e s u l t i n g b l e n d , m a i n l y c o n s i s t i n g o f components w i t h c a r b o n numbers o f 5 a n d 6, i s r e f e r r e d t o as C5-l80°F product." The b o i l i n g r a n g e s o f t h e d i s t i l l a t i o n c u t s (shown as " t r u e b o i l i n g p o i n t " t e m p e r a t u r e r a n g e s ) were c h o s e n a r b i t r a r i l y a n d do n o t r e p r e s e n t o p t i m u m o r maximum p o t e n t i a l y i e l d s o f s p e c i f i c p r o d u c t s . In the e x a m p l e s g i v e n , t h e amount o f j e t f u e l o r n a p h t h a c o u l d be a l t e r e d b y c h a n g i n g t h e b o i l i n g r a n g e s , d e p e n d i n g on t h e d e s i r e d p r o d u c t p r o p e r t i e s . Simil a r l y , t h e r e c y c l e c u t p o i n t c o u l d be v a r i e d t o m a x i mize i n d i v i d u a l products. A l l o f t h e p i l o t p l a n t t e s t s w e r e made a t 60 l i q u i d volume p e r c e n t p e r pass c o n v e r s i o n below the r e c y c l e cut p o i n t . T e m p e r a t u r e s were a d j u s t e d as necessary to maintain t h i s conversion. Total pressure and r e c y c l e gas r a t e were h e l d c o n s t a n t f o r a l l o f t h e runs w i t h a g i v e n feed. M

Feeds. P r o p e r t i e s o f two h y d r o f i n e d t e s t f e e d s are given i n Table I . The C a l i f o r n i a g a s o i l b l e n d was u s e d i n t e s t s s i m u l a t i n g a h y d r o c r a c k i n g u n i t p r o d u c i n g b o t h naphthas and j e t f u e l , the M i d - C o n t i n e n t blend i n t e s t s r e p r e s e n t i n g a u n i t producing naphtha as t h e major p r o d u c t . Catalysts. Seven e x p e r i m e n t a l c a t a l y s t s were p r e p a r e d w i t h v a r y i n g h y d r o g é n a t i o n a c t i v i t y and a c i d i t y t o t e s t t h e e f f e c t s o f t h e s e p r o p e r t i e s on product d i s t r i b u t i o n s . A l l o f the c a t a l y s t s were reasonably s t a b l e at t e s t c o n d i t i o n s . In the f o l l o w i n g t a b l e , the c a t a l y s t s are l i s t e d i n order of decreasing ratios of hydrogénation


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TABLE

I


FEED PROPERTIES

G r a v i t y , °API Aniline Point, °F S u l f u r , ppm T o t a l N i t r o g e n , ppm

Hydrotreated California Gas O i l B l e n d

Hydrotreated Mid-Continent Gas O i l B l e n d

33.9 192.7 1 0.1

33-3 177.6 9 0.2

31.3 56.3 12.4

19.4 63-9 16.6

553/589 595/617 646 684/732 763/859

325/441 515/616 666 705/762 802/826

Mass S p e c t r o m e t r i c Type A n a l y s i s , LV % Paraffins Naphthenes Aromatics ASTM D 1160 Distillation, St/5 10/30 50 70/90 95/EP

°P


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a c t i v i t y to acid a c t i v i t y . N o m i n a l l y , C a t a l y s t A has the highest h y d r o g é n a t i o n a c t i v i t y r e l a t i v e to i t s a c i d i t y ; C a t a l y s t G has t h e l o w e s t h y d r o g é n a t i o n a c t i v i t y r e l a t i v e to i t s a c i d i t y . The a s s i g n m e n t i s b a s e d on a v a r i e t y o f l a b o r a t o r y t e s t s . As i n d i c a t e d p r e v i o u s l y , a l l such t e s t s are not completely unambig u o u s ; t h e r e f o r e , t h e a s s i g n m e n t may be r e g a r d e d as somewhat a r b i t r a r y .


Experimental

Catalysts

Metals Catalyst IdentiHydrogénation Content, Wt % fication Component

Support M a t e r i a l

A

Pd

0.5

A c t i v a t e d Clay (Low A c i d i t y )

Β

Pd

1.0

Amorphous Alumina

Silica-

C

Pd

0.2

Amorphous Alumina

Silica-

D

Pd

0.5

Activated (Moderate

Clay Acidity)

Ε

Pd

0.5

Faujasite

Ρ

Pd

0.5

Amorphous S i l i c a Alumina (Activated)

G

Sulfided Ni

Results With C a l i f o r n i a

10.0

Amorphous Alumina

Silica-

Gas O i l

Product D i s t r i b u t i o n s . A l l o f the t e s t s w i t h C a l i f o r n i a g a s o i l w e r e made a t a r e c y c l e c u t p o i n t o f 550°F, a r b i t r a r i l y c h o s e n and n o t n e c e s s a r i l y an optimum c u t p o i n t f o r o p e r a t i o n w i t h any o f t h e catalysts. T a b l e I I compares p r o d u c t d i s t r i b u t i o n s f o r c a t a l y s t s near to the extremes o f h y d r o g e n a t i o n - t o acidity ratios studied. Catalyst Β gives a higher y i e l d o f l i q u i d p r o d u c t i n c l u d i n g the pentanes and a l l h i g h e r b o i l i n g m a t e r i a l ( r e f e r r e d t o as "C5-550°F


SULLIVAN

Catalyst Effects

A N D M E Y E R

TABLE I I YIELDS AND PRODUCT PROPERTIES FROM HYDROCRACKING OF CALIFORNIA GAS O I L 60% PER PASS CONVERSION BELOW 550°F

Catalyst T e m p e r a t u r e , °F LV %

Wt %

ΤΪ(Γ LV % Wt %


No L o s s P r o d u c t Y i e l d s ( B a s e d on F r e s h F e e d ) 0.01 0.02 1.0 3.8 1.1

Methane Ethane Propane Isobutane n-Butane C -180°F 180-280°F 280-300°F 300-550°F

10.1 21.6 4.9 59.2 95.8

5

Total

C -550°F 5

Chemical Hydrogen C o n s u m p t i o n , SCF/B Product

5.8 1.6

0.01 0.04 1.5 6.3 1.8

13.2 25.0 5.5 63-9

15.5 25.6 6.4 44.8

107.6

92.3

950

9.6 2.6 20.2 29.5 7.2 48.2

I 105.1 1000

Properties

C -180°F 5

Product

O c t a n e Number F - l Clear l80-280°F

85.0

58.7

63.4

47.5 52.5 0.0

42.6 55.5 1.9

44.0 56.0

40.1 57.5 2.4

42.6 57.2 0.2

41.5 56.0 2.5

Product

O c t a n e Number F - l Clear Type A n a l y s i s ,

LV %

Paraffins Naphthenes Aromatics 280-300°F

81.5

Product

Type A n a l y s i s ,

LV %

Paraffins Naphthenes Aromatics 300-550°F

Product

Type A n a l y s i s , Paraffins Naphthenes Aromatics ASTM D 86 D i s t . St/5 10/30 50 70/90 95/EP

LV %

Op

334/350 358/381 408 444/486 500/531

333/349 355/375 398 436/488 503/528


36

HYDROCRACKING

A N D

HYDROTREATING


product"). A l s o , t h i s c a t a l y s t p r o d u c e s more m a t e r i a l b o i l i n g above 280°F, a r b i t r a r i l y r e f e r r e d t o as j e t fuel. The p r o d u c t i s m o r e c o m p l e t e l y h y d r o g e n a t e d t h a n t h a t f o r C a t a l y s t G . C a t a l y s t G , on t h e o t h e r h a n d , p r o d u c e s more n a p h t h a , more p r o p a n e a n d b u t a n e , a n d h i g h e r octane numbers. The g e n e r a l t r e n d s shown b y t h e s e p r o d u c t d i s t r i b u t i o n s are i n b a s i c agreement w i t h the l i t e r a t u r e results discussed e a r l i e r . C -l80°F Product. T a b l e I I I shows t h e c o m p l e t e d i s t r i b u t i o n o f hydrocarbons from r e p r e s e n t a t i v e s a m p l e s o f C s - l 8 0 F p r o d u c t as d e t e r m i n e d by gas c h r o m a t o g r a p h y f o r t h e same t w o c a t a l y s t s . Both p r o d u c t s a m p l e s c o n t a i n a b o u t 90% p a r a f f i n s a n d 10$ cycloparaffins. The C 5 - l 8 0 ° F p r o d u c t f r o m C a t a l y s t G c o n t a i n s a t r a c e o f b e n z e n e (0.2%); t h a t f r o m C a t a l y s t Β c o n t a i n s no d e t e c t a b l e a r o m a t i c c o m p o u n d . The s m a l l d i f f e r e n c e i n t h e t o t a l c y c l o p a r a f f i n s c o n t e n t shown i n Table I I I i s p r o b a b l y not s i g n i f i c a n t . The C - l 8 0 ° F p r o d u c t c o n s i s t s m a i n l y o f C5 a n d C6 p a r a f f i n s ; t h e r e f o r e , i t i s p r i m a r i l y t h e s e components t h a t d e t e r m i n e t h e o c t a n e number. With a l l o f the c a t a l y s t s i n t h i s study, the r a t i o o f i s o p e n t a n e t o n o r m a l p e n t a n e v a r i e s d i r e c t l y as t h e r a t i o o f isohexanes to n-hexane. (In t h i s paper, the b r a n c h e d Ce p a r a f f i n s a r e c o l l e c t i v e l y r e f e r r e d t o a s isohexanes.) T h e r e f o r e , the i s o / n o r m a l r a t i o o f the p a r a f f i n s o f e i t h e r c a r b o n number c a n b e c o r r e l a t e d w i t h o c t a n e number f o r C s - l 8 0 F p r o d u c t o f a g i v e n c y c l o p a r a f f i n c o n t e n t a n d s e r v e as a c o n v e n i e n t i n d i c a t i o n o f c a t a l y s t performance. I n t h e s p e c i f i c example shown i n T a b l e I I I , t h e difference i n r a t i o s of i s o p a r a f f i n s to normal paraf f i n s i n t h e C - l 8 0 ° F p r o d u c t from t h e two c a t a l y s t s r e s u l t s i n a f o u r o c t a n e number d i f f e r e n c e . F i g u r e 1 shows t h e e f f e c t o f t e m p e r a t u r e o n isohexane/n-hexane r a t i o for Catalysts A - G , i n c l u s i v e . M o s t o f t h e c a t a l y s t s show a s l i g h t d e c r e a s e i n i s o - t o normal r a t i o w i t h i n c r e a s i n g temperature. The r a t i o s f o r t h e g r o u p o f c a t a l y s t s t e s t e d r a n g e f r o m 20/1 t o 3/1. The l a t t e r r a t i o i s a p p r o x i m a t e l y t h e e q u i l i b r i u m r a t i o f o r s i n g l y b r a n c h e d C6 p a r a f f i n s t o n o r m a l hexane. F i g u r e 2 i s a comparison showing the e f f e c t o f t e m p e r a t u r e on i s o p e n t a n e / n - p e n t a n e r a t i o s . The r e l a t i o n s h i p i s q u i t e s i m i l a r t o t h a t shown f o r t h e hexanes. 5

o

5

o

5


SULLIVAN

A N D M E Y E R

Catalyst Effects

TABLE

III

D I S T R I B U T I O N OP C - l 8 0 ° F PRODUCT PROM HYDROCRACKING OP C A L I F O R N I A GAS O I L


5

1

Catalyst Average C a t a l y s t Temperature, °F Product,

LV % o f

Paraffins

Cycloparaffins

Benzene Total

598

610

5

Cyclopentane Methylcyclopentane Cyclohexane Dlmethylcyclopentanes, Ethylcyclopentane Methylcyclohexane Total

G

C -l80°F

Butanes Isopentane n-Pentane 2.2- Dimethylbutane 2.3- Dimethylbutane 2- M e t h y l p e n t a n e 3- M e t h y l p e n t a n e n-Hexane Isoheptanes n-Heptane Total

Β

Aromatics

0.4 41.0 9.5 0.2 2.5 17.3 9.3 6.3 3.7 0.1

0.3 44.1 2.8 0.04 3.2 19.3 11.4 2.2 4.5 0.02

90.3

87.8

0.5 7.1 0.6 1.3

0.4 9.4 0.4 1.5

0.1

0.3

9.6

12.0

-

0.2 0.2

81.1

85.0

Isopentane/n-Pentane

4.3

16.4

Isohexanes/n-Hexane

4.6

15.5

Octane

No., F - l Clear


HYDROCRACKING AND HYDROTREATING


20 Γ-

600

630

Average Catalyst Temperature,

°F

Figure 1. Effect of temperature on isohexanes/n-hexane hydrocracking of California gas oil

|Τ0 40

201

550

600

650

Average C a t a l y s t T e m p e r a t u r e ,

700 °F

Figure 2. Effect of temperature on isopentane/n-pentane hydrocrack ing of California gas oil


2.

SULLIVAN AND MEYER

Catalyst Effects


W i t h b o t h pentanes and hexanes, the r a t i o s appear to vary i n v e r s e l y w i t h the to-acidity ratios.

39 iso-to-normal hydrogenation-

Butanes. The b u t a n e s a r e t h e p r i n c i p a l l o w b o i l i n g p r o d u c t s ; a n d , as i n d i c a t e d e a r l i e r , c a t a l y s t s w i t h a low r a t i o o f h y d r o g é n a t i o n a b i l i t y to a c i d i t y p r o d u c e more b u t a n e t h a n do t h o s e w i t h r e l a t i v e l y h i g h hydrogénation activity. However, the d i f f e r e n c e s i n i s o b u t a n e / n - b u t a n e r a t i o s among c a t a l y s t s o f w i d e l y d i f f e r e n t h y d r o g e n a t i o n - t o - a c i d i t y r a t i o s are small. F i g u r e 3 shows t h e e f f e c t o f t e m p e r a t u r e on i s o b u t a n e / η - b u t a n e r a t i o f o r C a t a l y s t s A , B , F , and G , r e p r e s e n t i n g extremes o f h y d r o g e n a t i o n / a c i d i t y r a t i o s . The isobutane/n-butane r a t i o with Catalyst G i s s l i g h t l y h i g h e r than t h a t f o r the other c a t a l y s t s at the lower temperatures. However, at h i g h e r temperatures, the r a t i o s from a l l o f the c a t a l y s t s are e s s e n t i a l l y the same. T h i s r e s u l t i n d i c a t e s t h a t t h e r e i s no d i r e c t r e l a t i o n s h i p between i s o / n o r m a l r a t i o s f o r the butanes w i t h those f o r the pentanes and hexanes. The f o l l o w i n g hypothesis i s suggested to e x p l a i n t h i s r e s u l t . An i m p o r t a n t r e a c t i o n o c c u r s i n h y d r o c r a c k i n g w h i c h p r o d u c e s i s o b u t a n e more s e l e c t i v e l y f r o m c y c l o p a r a f f i n s t h a n from a r o m a t i c compounds. This reaction has b e e n r e f e r r e d t o as t h e p a r i n g r e a c t i o n . I t was s h o w n b y E g a n e t a l . (17) t h a t c y c l o p a r a f f i n s w i t h c a r b o n n u m b e r s o f 10 o r m o r e r e a c t v e r y s e l e c t i v e l y t o give isobutane plus lower molecular weight c y c l o paraf fins. A l k y l aromatics with side chains of three o r more c a r b o n s c r a c k m a i n l y b y d é a l k y l a t i o n , w i t h much l e s s i s o m e r i z a t i o n o f t h e a l k y l g r o u p (18.)· Therefore, i f the aromatics i n the feed are hydrog e n a t e d p r i o r t o c r a c k i n g , as w o u l d be e x p e c t e d w i t h a catalyst of high hydrogénation a c t i v i t y , a high isobutane/n-butane r a t i o i s favored. With a catalyst o f l o w e r h y d r o g é n a t i o n a c t i v i t y , c r a c k i n g w o u l d be expected to occur to a greater extent before hydrogénation. Therefore, a lower isobutane/n-butane ratio w o u l d be e x p e c t e d . H o w e v e r , b u t a n e s a r e p r o d u c e d by c r a c k i n g r e a c t i o n s other than the p a r i n g r e a c t i o n . In reactions s u c h a s p a r a f f i n c r a c k i n g , t h e same f a c t o r s t h a t f a v o r a h i g h i s o p e n t a n e / n - p e n t a n e r a t i o and a h i g h i s o p e n t a n e / n - p e n t a n e r a t i o and a h i g h i s o h e x a n e s / n-hexanes r a t i o ( i . e . , h i g h a c i d i t y ) w i l l f a v o r a h i g h isobutane/n-butane ratio. T h e r e f o r e , we h a v e t w o e f f e c t s o n i s o b u t a n e / η - b u t a n e r a t i o t h a t tend to o f f s e t each o t h e r . The r e s u l t , w i t h t h e C a l i f o r n i a gas o i l , i s t h a t t h e r e i s


40

HYDROCRACKING A N D H Y D R O T R E A T I N G


l i t t l e e f f e c t o f c h a n g i n g a c i d i t y and h y d r o g é n a t i o n a c t i v i t y on t h e i s o b u t a n e / n - b u t a n e ratio. This r e l a t i o n s h i p w i l l vary w i t h the aromatic cont e n t of the feedstock. With a highly aromatic feed, t h e c a t a l y s t w i t h t h e h i g h e r h y d r o g é n a t i o n a c t i v i t y may give a higher isobutane/n-butane r a t i o , although with the pentanes and hexanes the e f f e c t i s r e v e r s e d . T o t a l L i q u i d (C5+) Y i e l d . Product molecules w i t h c a r b o n numbers o f f i v e a n d h i g h e r c a n be c o m b i n e d i n a f r a c t i o n r e f e r r e d t o as "C5+" l i q u i d p r o d u c t . This f r a c t i o n i n c l u d e s the pentanes and a l l o f the p r o d u c t b o i l i n g below the r e c y c l e cut p o i n t . The e x a m p l e s i n T a b l e I I show t h a t t h e m o r e a c i d i c c a t a l y s t p r o d u c e s l e s s p r o d u c t i n t h e C 5 + f r a c t i o n , more b u t a n e s a n d p r o p a n e , and l e s s p r o d u c t i n the j e t f u e l b o i l i n g range t h a n does t h e c a t a l y s t w i t h h i g h e r h y d r o g é n a t i o n activity. F i g u r e 4 shows t h a t t h e t o t a l C5+ y i e l d c a n be r e l a t e d to the r a t i o of the isohexanes/n-hexane. No r e s u l t s a r e i n c l u d e d f o r C a t a l y s t A a s no a n a l y s e s w e r e a v a i l a b l e i n t h i s temperature range. W i t h i n t h i s r e a s o n a b l y narrow temperature span and w i t h p r e s s u r e and gas r a t e c o n s t a n t , t h e r e s u l t s correlate quite well. The same g e n e r a l f a c t o r s w h i c h contribute to a high t o t a l l i q u i d y i e l d also result i n a l o w e r i s o - t o - n o r m a l r a t i o and v i c e v e r s a . I t s h o u l d be e m p h a s i z e d t h a t i n a c t u a l p r a c t i c e i t i s t h e maximum f i n i s h e d p r o d u c t r a t h e r t h a n t h e q u a n t i t y o f C5+ h y d r o c r a c k a t e t h a t i s t h e most c r i t i c a l y i e l d a f f e c t i n g economic e v a l u a t i o n s o f h y d r o c r a c k i n g catalysts. A p o r t i o n o f the hydrocracked naphtha i s u s u a l l y c a t a l y t i c a l l y reformed to produce h i g h octane gasoline. K i t t r e l l , S c o t t , and L a n g l o i s (19) p r e s e n t e d and i n t e r p r e t e d r e s u l t s showing t h e optimum r e l a t i o n s h i p between h y d r o c r a c k i n g and r e f o r m i n g . Such a r e l a t i o n s h i p c a n be u s e d i n c o n j u n c t i o n w i t h r e s u l t s of the type d e s c r i b e d here to evaluate s p e c i f i c hydrocracking catalysts. Jet Y i e l d . F i g u r e 5 shows t h e r e l a t i o n s h i p b e t w e e n t h e y i e l d o f j e t ( a r b i t r a r i l y d e f i n e d as t h e p r o d u c t b o i l i n g between 2 8 0 ° F and 5 5 0 ° F ) and the i s o to-normal r a t i o f o r the hexanes. Although there i s more v a r i a t i o n h e r e t h a n shown f o r t h e t o t a l l i q u i d y i e l d , t h i s e m p i r i c a l r e l a t i o n s h i p i s r e a s o n a b l y good f o r most o f t h e c a t a l y s t s .

order

Preferential Poisoning of Catalytic Sites. In t o show t h a t y i e l d s a n d C s - 1 8 0 ° F o c t a n e n u m b e r s


2.

SULLIVAN

41

Catalyst Effects

A N D M E Y E R


• • • Ο

600 Average

Catalyst

Catalyst A Catalyst Β Catalyst F Catalyst G

650 Temperature,

700 °F

Figure 3. Effect of temperature on isobutane/n-butane hydrocracking of California gas oil

ο

T3 -a- LJa> OJ

%

—

95

—

94

—

93

Έ "

92

•σ »

91

cr

90

—

+

89

—

Ο

Rft

>- -c

I

• A • ^ • Ο

Catalyst Β Catalyst C Catalyst D Catalyst Ε Catalyst F Catalyst G

I 10

15

20

I sohexanes/n-Hexane

Figure 4. Relationship between liquid yield and isohexanes/n-hexane at 590^615°F hydrocracking of California gas oil



42

HYDROCRACKING

A N D HYDROTREATING

a r e d i r e c t l y r e l a t e d t o t h e hydrogénation t o a c i d i t y r a t i o , s e v e r a l experiments were made w i t h C a t a l y s t C i n which c a t a l y t i c s i t e s were p r e f e r e n t i a l l y p o i s o n e d . N i t r o g e n (as q u i n o l i n e ) was used as a p o i s o n f o r a c i d s i t e s ; s u l f u r (as d i m e t h y l d i s u l f i d e ) was used t o p o i s o n the m e t a l hydrogénation s i t e s . Admittedly, either p o i s o n may i n f l u e n c e b o t h s e t s o f c a t a l y t i c s i t e s somewhat; however, i t i s r e a s o n a b l e t o assume t h e s e s e c o n dary e f f e c t s would be r e l a t i v e l y minor. T a b l e IV shows t h e r e s u l t s . When t h e a c i d i t y i s p r e f e r e n t i a l l y p o i s o n e d by e q u i l i b r a t i n g t h e c a t a l y s t w i t h a f e e d c o n t a i n i n g 8 ppm o f n i t r o g e n , t h e f o l l o w i n g e f f e c t s are noted: (1) T o t a l l i q u i d y i e l d i n c r e a s e s by about 1 wt %\ (2) t h e j e t f u e l i n c r e a s e s by 6 LV %\ (3) t h e C5-l80°P octane number d e c r e a s e s by two numbers. When t h e hydrogénation a c t i v i t y i s p r e f e r e n t i a l l y p o i s o n e d by o p e r a t i n g w i t h 100 ppm o f s u l f u r i n t h e f e e d , (1) t h e t o t a l l i q u i d y i e l d d e c r e a s e s by about 2%; (2) t h e j e t f u e l d e c r e a s e s by 6-755; (3) t h e octane number o f t h e C s - l 8 0 F p r o d u c t i n c r e a s e s by more than t h r e e numbers. o

C a t a l y s t Aging E f f e c t s . The y i e l d s f o r most o f the c a t a l y s t s remain r e l a t i v e l y s t a b l e w i t h c a t a l y s t aging. I n c o n s t a n t c o n v e r s i o n runs such as t h e s e , t h e c a t a l y s t temperature i s i n c r e a s e d t o m a i n t a i n c o n v e r s i o n ; and y i e l d s t a b i l i t y can be shown by a p l o t o f y i e l d v e r s u s average c a t a l y s t t e m p e r a t u r e . Figure 6 shows r e s u l t s f o r two amorphous c a t a l y s t s . F i g u r e 7 shows t h e R e l a t i o n s h i p between C 5 + l i q u i d y i e l d and isohexanes/n-hexane r a t i o i n t h e temperature range 640-660°F. The r e l a t i o n s h i p i s s t i l l good f o r most o f t h e c a t a l y s t s ; t h e average C 5 + y i e l d a t a g i v e n isohexanes/n-hexane r a t i o i s perhaps 0.5% lower t h a n t h a t shown i n F i g u r e 4 f o r t h e temperature range 590-6l5°F. A n o t a b l e e x c e p t i o n t o t h e r e l a t i o n s h i p shown i n Figure 7 i s C a t a l y s t Ε with a f a u j a s i t e support. In t h e temperature span between 640°F and 660°F, t h e t o t a l l i q u i d y i e l d decreases r a p i d l y without s i g n i f i c a n t change i n t h e isohexanes/n-hexane ratio. F i g u r e 8 shows t h e r e l a t i o n s h i p s between tempera t u r e , C 5 + y i e l d , and j e t y i e l d f o r C a t a l y s t E. C 5 + y i e l d i s r e l a t i v e l y s t a b l e t o 640°F; however, a s h i f t i n p r o d u c t d i s t r i b u t i o n from j e t f u e l t o naphtha o c c u r s between 6l0°F and 640°F. Above 660°F ( o f f s c a l e i n t h e p l o t s i n F i g u r e s 7 and 8 ) , t h e C 5 + and j e t f u e l y i e l d c o n t i n u e t o d e c r e a s e rapidly. At 677°F t h e C + l i q u i d y i e l d i s 80.4 wt %; the 280-550°F j e t y i e l d i s 15.1 LV %. 5



2.

SULLIVAN

A N D M E Y E R

Catalyst Effects

43

TABLE IV PRODUCT FROM CATALYST C WITH CALIFORNIA GAS OIL EFFECTS OF SULFUR AND NITROGEN

Isohexanes/ n-Hexane

c+ Yield, Wt %

280°F+ Yield, LV %

C -180°F Octane, F-l Clear 5

Catalyst Temperat u r e , °F

5

Before A d d i t i o n of S u l f u r or N i t r o g e n

609 640

4.9 4.7

94.3 95.2

65.3 64.7

81.0 80.0

8 ppm N i t r o g e n Added to Feed ( C a t a l y s t Equilibrated)

650

3.0

95.8

71.0

78.0

100 ppm S u l f u r Added to Feed ( A f t e r 170 Volumes of Feed Containing Sulfur)

620

12.7

92.7

58.3

84.2



100 rCatalyst Β

Λ

95 Catalyst G

ΤΤΟ Downloaded by UNIV OF CALIFORNIA SAN DIEGO on December 29, 2015 | http://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0020.ch002

90

JL

85

600

550 Average

700

650

Catalyst

Temperature,

°F

+

Figure 6. Effect of temperature on C liquid yield hydrocracking of Cali fornia gas oil 5

ι *641°F

644°F^

*645°F / • Catalyst A • Catalyst Β A Catalyst C $L Catalyst C + 8 ppm Ν in Feed * Catalyst Ε • Catalyst F Ο Catalyst G

Î9°F

90h

I 652°F*

Numbers by points for Catalyst Ε indicate temperatures.

l_

5

I

I

10

15

I sohexanes/n-Hexane +

Figure 7. Relationship between C yield and isohexanes/n-hexane 640^-660°F 5


SULLIVAN

A N D

M E Y E R

Catalyst Effects


2.


45


46


The y i e l d s h i f t s f o r t h e s e f a u j a s i t e - c o n t a i n i n g c a t a l y s t s a r e a c c o m p a n i e d by a b u i l d u p o f h i g h b o i l i n g m a t e r i a l (650°F+) i n the l i q u i d r e c y c l e stream. The s h a p e s e l e c t i v e p r o p e r t i e s o f t h e a g e d f a u j a s i t e c a t a l y s t appear to a f f e c t the product d i s t r i b u tion. Composition o f the r e c y c l e stream i n d i c a t e s the r a t e o f r e a c t i o n o f the higher b o i l i n g molecules i s very low. Because h i g h m o l e c u l a r weight molecules d i d c r a c k more r e a d i l y i n t h e e a r l y p a r t o f t h e r u n , t h i s r e s u l t suggests that deposits o f carbonaceous m a t e r i a l ("coke") cause p a r t i a l p l u g g i n g o f the c a t a l y s t p o r e s . T h e r e f o r e , the l a r g e r m o l e c u l e s have l i m i t e d access t o catalytic sites. The h i g h r a t e o f c o k i n g i n a n a r r o w t e m p e r a t u r e r a n g e may b e r e l a t e d t o t h e h y d r o g e n a t i o n d e h y d r o g e n a t i o n e q u i l i b r i a o f c e r t a i n p o l y c y c l i c compounds w h i c h , i f d e h y d r o g e n a t e d , a r e w e l l known c o k e precursors. The r a t e o f c a t a l y s t d e a c t i v a t i o n , a s m e a s u r e d b y the temperature increase r e q u i r e d to m a i n t a i n convers i o n , does n o t i n c r e a s e a p p r e c i a b l y d u r i n g t h e p e r i o d that the y i e l d s h i f t occurs. The c a t a l y s t r e m a i n s a c t i v e f o r the c r a c k i n g o f r e l a t i v e l y low b o i l i n g molecules. However, the low y i e l d o f p r o d u c t i n the j e t b o i l i n g range i n d i c a t e s t h a t , at the c o n v e r s i o n l e v e l s u s e d , much i n i t i a l p r o d u c t f r o m t h e j e t b o i l i n g range i s f u r t h e r c r a c k e d t o naphtha and l i g h t g a s e s . The s e c o n d a r y c r a c k i n g o f p r o d u c t i n t h e j e t r a n g e may be t h e r e s u l t o f s e v e r a l f a c t o r s : ( 1 ) The r a t e s o f d i f f u s i o n o f j e t p r o d u c t o u t o f t h e c a t a l y s t may b e s l o w due t o t h e p a r t i a l p o r e p l u g g i n g . The l o n g e r r e s i d e n c e t i m e o f t h e j e t p r o d u c t p e r m i t s much s e c o n dary c r a c k i n g . (2) P a r t i a l p o r e p l u g g i n g does n o t a l l o w a s many o f t h e h i g h e r b o i l i n g r e a c t a n t m o l e c u l e s to reach the c a t a l y t i c s i t e s . Therefore, there i s l e s s c o m p e t i t i o n f o r c a t a l y t i c s i t e s ; and the apparent r a t e o f r e a c t i o n o f m o l e c u l e s i n t h e j e t r a n g e may increase. The c a t a l y s t a g i n g e f f e c t s s h o w n b y t h i s f a u j a s i t e c o n t a i n i n g c a t a l y s t a p p e a r t o be a g e n e r a l phenomenon; s i m i l a r e f f e c t s have been o b s e r v e d i n o u r l a b o r a t o r i e s w i t h o t h e r f e e d s t o c k s and o t h e r z e o l i t e containing catalysts. Other examples have been reported i n the patent l i t e r a t u r e (20). T h i s c a t a l y s t a g i n g p r o p e r t y does n o t n e c e s s a r i l y make s u c h a c a t a l y s t u n a t t r a c t i v e . R a t h e r , i t may l i m i t the temperature span i n which a d e s i r e d product d i s t r i b u t i o n c a n be o b t a i n e d . W i t h most amorphous c a t a l y s t s , a run i s u s u a l l y terminated at the p o i n t at which c a t a l y s t a c t i v i t y and s t a b i l i t y are sufficiently l o w t h a t c o n t i n u a t i o n o f t h e r u n i s no l o n g e r


2.

SULLIVAN

A N D M E Y E R

attractive. the product

With c e r t a i n z e o l i t e - c o n t a i n i n g d i s t r i b u t i o n may b e t h e l i m i t i n g


Results With Mid-Continent

47

Catalyst Effects

catalysts, factor.

Gas O i l

C a t a l y s t C and C a t a l y s t G were compared f o r t h e h y d r o c r a c k i n g o f t h e M i d - C o n t i n e n t gas o i l a t 4 0 0 ° F r e c y c l e c u t p o i n t w i t h n a p h t h a as t h e m a j o r p r o d u c t . Table I l i s t s the p r o p e r t i e s o f the h y d r o f i n e d f e e d ; T a b l e V shows y i e l d s a n d p r o d u c t p r o p e r t i e s a t comparable c o n d i t i o n s , and T a b l e V I g i v e s d e t a i l e d chromatographic analyses of representative Cs-l80°F products. The t r e n d s a r e g e n e r a l l y t h e same a s t h o s e a t t h e h i g h e r c u t p o i n t w i t h C a l i f o r n i a g a s o i l . The c a t a l y s t w i t h the higher r a t i o of h y d r o g é n a t i o n a c t i v i t y to a c i d i t y , C a t a l y s t C , p r o d u c e s more C 5 + n a p h t h a ; t h e more h i g h l y a c i d i c c a t a l y s t , C a t a l y s t G , y i e l d s p r o d u c t w i t h a h i g h e r octane number. Conclusions Most d u a l f u n c t i o n a l h y d r o c r a c k i n g c a t a l y s t s e x h i b i t an i n v e r s e r e l a t i o n s h i p between C5+ l i q u i d and t h e P - l c l e a r o c t a n e number o f t h e C 5 - C 6 p r o d u c t . P r e f e r e n t i a l p o i s o n i n g o f e i t h e r the a c i d s i t e s or the hydrogenation-dehydrogenation c a t a l y t i c sites indicates t h a t b o t h the y i e l d s and octanes are r e l a t e d t o the r a t i o o f h y d r o g é n a t i o n t o a c i d i t y p r o v i d e d by t h e c a t a lyst. A h i g h r a t i o favors h i g h l i q u i d y i e l d s ; a low r a t i o favors h i g h octane product. Some m o d e s t c h a n g e s i n t h e r e l a t i o n s h i p b e t w e e n C5+ y i e l d a n d l i g h t n a p h t h a o c t a n e number o c c u r as c a t a l y s t temperature i s i n c r e a s e d . Also, with certain aged c a t a l y s t s s u c h as t h o s e c o n t a i n i n g f a u j a s i t e , changes i n c a t a l y s t geometry b r o u g h t about by p o r e p l u g g i n g due t o c a r b o n a c e o u s d e p o s i t s may c a u s e s u b s t a n t i a l d e v i a t i o n s from t h i s r e l a t i o n s h i p . Acknowledgment The a u t h o r s w i s h t o t h a n k M e s s r s . G . E . and C. J . Egan f o r t h e i r h e l p f u l s u g g e s t i o n s the course of t h i s work.

Langlois during

Abstract Yields and product properties in hydrocracking are influenced by the relationship between catalyst acidity and the hydrogenation-dehydrogenation activity of the


48


TABLE V Y I E L D S AND PRODUCT PROPERTIES FROM HYDROCRACKING OF MID-CONTINENT GAS O I L 60% PER PASS CONVERSION BELOW 4 0 0 ° F


Catalyst Average C a t a l y s t No L o s s P r o d u c t ( B a s e d on F r e s h

Temp.,

°F

G 632 Wt % L V %

Yields Feed) 0.02 0 . 04 1.7 7.5 2.1 19.1 33-6 38.1

Methane Ethane Propane Isobutane n-Butane C -l80°F 180-280°F 280-400°F 5

90.8

Total C -400°F 5

Chemical Hydrogen Consumption, SCF/B Product

C 6:!4 Wt % L V %

0.03 0.09 2.4 11.4 9-5 2.9 3-1 2 4 . 8 21.3 39-0 3 3 . 2 4 1 . 9 32.9 105.7

1220

14.4 4.2 27.7 38.2 35.9 101.8

87.4 1245

Properties

C -180°F 5

Octane N o . , F - l C l e a r

81.1

85.7

45.3

55.2

40.5 59.0 0.5

37.8 56.1 6.1

220/236 242/264 288 318/356 368/408

214/228 235/255 279 309/350 365/407

l80-400°F Octane N o . , F - l C l e a r Type A n a l y s i s , LV % Paraffins Naphthenes Aromatics ASTM D 86 Distillation, St/5 10/30 50 70/90 95/EP

°F


SULLIVAN

A N D M E Y E R

Catalyst Effects

TABLE V I D I S T R I B U T I O N OF C - l 8 0 ° F PRODUCT FROM HYDROCRACKING OF MID-CONTINENT GAS O I L


5

Catalyst Average C a t a l y s t Temperature, °F Product,

Paraffins

Cycloparaffins

642

0.8 36.6 8.7 0.3 2.9

Aromatics

0.2

44.6 3.5

16.9 10.1

0.1 3.8 19.5 11.2

87.4

88.3

0.5 1.7

0.5 8.4 0.7 1.5

0.4

0.2

12.6

11.3

6.6 4.5

9.1

0.9

-

Benzene Total

627 5

Cyclopentane MethyIcyclopentane Cyclohexane Dlmethylcyclopentanes, Ethylcyclopentane MethyIcy clohexane Total

G

LV % o f C - l 8 0 ° F

Butanes Isopentane n-Pentane 2 . 2 - DimethyIbutane 2.3- DlmethyIbutane 2- Methylpentane 3- M e t h y l p e n t a n e n-Hexane Isoheptanes Total

C

-

1.8 3.6

0.3 0.3

81.3

85-7

Isopentane/n-Pentane

4.2

12.7

Isohexanes/n-Hexane

4.6

19.2

Octane

No., F - l Clear



50


dual functional catalysts employed. Hydrocracking catalysts can be tailored to meet specific refining objectives. In this paper both amorphous and crys talline catalysts of varying acidity and hydrogenation activity are examined at constant process conditions for (1) producing both jet fuel and gasoline and (2) producing gasoline as the major product. In general, as the hydrogenation activity of the catalyst is increased relative to its acidity, total liquid product (C5+) yield increases; and the octane number of the light naphtha (C5-C6) decreases. The reverse is also true. If either the acidity or hydrogenation activity is preferentially poisoned, the change is reflected in the yields and the C5-C6 octane number. Literature Cited 1. 2. 3. 4. 5. Vol 6. 7. 8. 9. 10. 11. 12. 13.

Scott, J . W., and Kittrell, J. R., Ind. Eng. Chem. (1969), 61, 18. Baral, W. J., and Huffman, H. C., World Petroleum Congress, Preprint PD 12 (1), (1971). Hansford, R. C., U.S. Patent 3,499,835 (March 10, 1970). Beuther, Η., and Larson, O. Α., Ind. Eng. Chem. Proc. Design Dev. (1965), 4, 177. Voorhies, Α., and Smith, W. Μ., Chapter in "Advances in Petroleum Chemistry and Refining," 8, ρ 1693 Interscience Publishers, New York (1964). Larson, O. Α., MacIver, D. S., Tobin, H. H., and Plinn, R. Α., Ind. Eng. Chem. Proc. Design Dev. (1962), 1, 300. Langlois, G. E., Sullivan, R. F., and Egan, C. J., J. Phys. Chem. (1966), 70, 3666. Doane, E. P., Preprints, Div. Petroleum Chem., (1967), ACS 12, (4), B-139. Coonradt, H. L., and Garwood, W. E., Ind. Eng. Chem. Proc. Design Dev. (1964), 3, 38. Langlois, G. E., and Sullivan, R. F., Advances in Chemistry Series No. 97, "Refining Petroleum for Chemicals," Chapter 3, p 38, ACS (1970). Beuther, H., McKinley, J. Β., and Flinn, R. Α., Preprints, Div. Petroleum Chem., (1961), ACS 6, (3), A-75. Coonradt, H. L., Ciapetta, F. G., Garwood, W. Ε., Leaman, W. Κ., and Maile, J. N., Ind. Eng. Chem. (1961), 53, 727. Coonradt, H. L., Leaman, W. Κ., Maile, J. Ν., Preprints, Div. Petroleum Chem., (1964), ACS 9, (1), 59.


2. 14. 15. 16. 17.


18. 19. 20.

SULLIVAN

AND

MEYER

Catalyst Effects

51

Coonradt, H. L., and Garwood, W. Ε . , Preprints, D i v . P e t r o l e u m Chem., ( 1 9 6 7 ) , ACS 12 (4), B - 4 7 . S c h u l z , H., and Weitkamp, J., I n d . Eng. Chem. Prod. Res. Develop., ( 1 9 7 2 ) , 11 ( 1 ) , 46. Myers, C. G., Garwood, W. Ε . , Rope, B. W., W a d l i n g e r , R. L., and Hawthorne, W. P., J. Chem. Eng. Data ( 1 9 6 2 ) , 7 , 257. Egan, C. J., L a n g l o i s , G. Ε . , and White, R. J., J . Am. Chem. Soc., ( 1 9 6 2 ) , 84, 1204. S u l l i v a n , R. F., Egan, C. J., and L a n g l o i s , G. E . , J . C a t a l y s i s ( 1 9 6 4 ) , 3 , 183. Kittrell, J . R., L a n g l o i s , G. E . , and S c o t t , J . W., Hydrocarbon P r o c e s s ( 1 9 6 9 ) , 48, (5), 116. Hanson, F. V., and Snyder, P. W., U.S. P a t e n t 3 , 5 2 3 , 8 8 7 (August 1 1 , 1 9 7 0 ) .


Hydrocracking and Hydrotreating

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