processing of shale oil for potential lubricating oil base stocks.pdf

7/27/2019 processing of shale oil for potential lubricating oil base stocks.pdf

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Fuel Processing Technology, 37 (1994) 29 ~3 05 295E l s e v i e r S c i e n c e B . V ., A m s t e r d a m

P r o c e s s i n g o f s h a l e o i l f o r p o t e n t i a l l u b r i c a t i n g o i l b a s es t o c k sJ . F . S t u b i n g t o n * , G . D . S e r g e a n t , D . B a r r e t t , P . T . D . H . D o a n d K . A . R a v a lDepartment of Fuel Technology, School of Chemical Engineering and Industrial Chemistry,University of New South Wales, P.O. Box 1, Kensington, N.S.W., 2033 (Australia)( R e c e i v e d M a r c h 1 2, 1 99 3 ; a c c e p t e d i n r e v i s e d f o r m S e p t e m b e r 2 0 , 1 99 3)

A b s t r a c tM u c h o f t h e e m p h a s i s o n s h a l e o i l p ro c e s s i n g r e s e a r c h h a s b e e n t o w a r d s t h e p r o d u c t i o n o f t h et r a n s p o r t f u e ls , d i e s e l o i l a n d g a s o l i n e , a s a n a l t e r n a t i v e t o p e t r o l e u m c r u d e o i l p r o d u c t s . T h i sr e s e a r c h p r o j e c t w a s a i m e d a t a b r o a d e r p r o d u c t r a n g e a n d s p e c i f ic a l l y d i r e c t e d to e v a l u a t e t h ep o t e n t i a l f o r t h e p r o d u c t i o n o f l u b r i c a t i n g o i l b a s e s t o c k s f r om t h e h i g h b o i l i n g d i s t i l l a t e f ra c t i o na n d r e s i d u a l m a l t e n e s o f s h a l e o i l. T h e p r o c e s s i n g s t ep s i n c l u d e d v a c u u m d i s t i l l a t i o n , s o l v e n te x t r a c t i o n , a l k y l a t i o n , d e - w a x in g , an d h y d r o g e n a t i o n o f t h e s h a l e o i l fr o m R u n d l e a n d S t u a r t o i ls h a l e d e p o s i t s in Q u e e n s l a n d , A u s t r a l i a . Y i e l d s o f t h e p r o d u c t s w e r e m e a s u r e d a t e a c h s t a g e o f t h ep r o c e s s a n d t h e e l e m e n t a l c o m p o s i t i o n s d et e r m i n e d . T h e a n a l y s e s w e r e c o m p a r e d w i t h t h o s e o f t h ep e t r o l e u m - d e r i v e d l u b r i c a t i n g o i l b a s e s t o c k s. S i g n i f i c a n t y i el d s w e r e o b t a i n e d i n t h e l u b r i c a t i n go i l b o i l i n g r a n g e , b u t t h e e l e m e n t a l a n a l y s i s s h o w e d t h a t t h e p r o d u c t s w e r e s t i l l lo w e r i n h y d r o g e n ,c o m p a r e d t o t h e p e t r o l e u m p r o d u c t s . F u r t h e r i n v e s t i g a t i o n o f t h e R u n d l e d i s t i l l a t e is w a r r a n t e d ,u s i n g m o r e r i g o r o u s e x t r a c t i o n a n d h y d r o g e n a t i o n c o n d i t i o n s .

1 . I N T R O D U C T I O NO i l s h a l e i s p r o c e s s e d b y p y r o l y s i s ( i .e . h e a t i n g i n t h e a b s e n c e o f a i r ) in

v a r i o u s d e s i g n s o f r e t o r t t o p r o d u c e s h a l e o i l . T h e p r i m a r y o b j e c t i v e o f e a r l i e rr e s e a r c h h a s b e e n t o w a r d s t h e p r o d u c t i o n o f t r a n s p o r t f u e ls , g a s o l i n e a n dd i e s e l , f r o m o i l s h a l e a s a n a l t e r n a t i v e s o u r c e t o c o n v e n t i o n a l p e t r o l e u m c r u d eo i l p r o d u c t s . H e n c e , t h i s p r e v i o u s r e s e a r c h h a s c o n c e n t r a t e d o n t h e d e t e r m i n a -t i o n o f t h e y i e l d s [ 1 ], k i n e t i c s [2 ] a n d c h e m i c a l c h a r a c t e r i z a t i o n [1 , 3 , 4 ] o f t h es h a l e o i l s p r o d u c e d b y p y r o l y s i s p r o c e s s e s . P r o c e s s d e v e l o p m e n t h a s a i m e d a tt h e d e v e l o p m e n t o f a d v a n c e d r e t o r t i n g t e c h n o l o g y [5 , 6 ], i n c l u d i n g m a t h e m a t -i c a l m o d e l l i n g [7 ] , t o m a x i m i s e l i q u i d f u e l y i e l d s .

A n i m p o r t a n t f a c t o r i n h e l p i n g t o e s t a b l i s h a s h a l e o i l i n d u s t r y i n A u s t r a l i am a y b e t h e d e v e l o p m e n t o f a b r o a d e r p r o d u c t s l a t e t h a t i n c l u d e s b i t u m e n a n dl u b r i c a t i n g o i l s . I t w a s s h o w n i n a p r i o r p r o j e c t [8 , 9 ] t h a t b i t u m e n p r o d u c e df r o m th e v a c u u m r e s i d u e o f R u n d l e a n d S t u a r t s h a l e o i l s m e t r o a d g r a d es p e c i f i c a t i o n s , b a s e d o n s t a n d a r d l a b o r a t o r y t e s t s . T h i s w o r k i s n o w b e i n g

* C o r r e s p o n d i n g a u t h o r .

0 3 78 -3 8 20 /9 4 /$ 0 7.00 1 9 9 4 E l se v i e r Sc i e n c e B .V .SSDI 0 3 7 8 - 3 8 2 0 ( 9 3 ) E 0 1 0 0 - S


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29 6 J .F . S tub in g ton e t a l . /F ue l Pr o ces s ing Techno l . 37 (1994) 295-30 5e x t e n d e d t o i n v e s t i g a t e t h e p o t e n t i a l f o r l u b r i c a t i n g o il p r o d u c t i o n f r o m t h es a m e s h a l e o i l s .

2 . PROCESSING OF SHALE OILT w o d i f f e r e n t s t a r t i n g m a t e r i a ls f r o m o i l s h a l e d e p o s i ts i n Q u e e n s l a n d w e r e

a v a i l a b l e :( a) s h a l e o i l f ro m t h e R u n d l e d e p o s i t , w h i c h h a d b e e n t o p p e d a t 2 0 0 C a t

a t m o s p h e r i c p r e s s u r e t o r e m o v e t h e g a s o l i n e f r a c t io n ;(b ) r e s i d u e f r o m t h e h i g h - t e m p e r a t u r e a t m o s p h e r i c d i s t i l l a t i o n o f s h a l e o i l

f r o m th e S t u a r t d e p o s i t .T h e R u n d l e s a m p l e w a s f i r s t d is t il le d u n d e r v a c u u m t o r e m o v e t h e r e m a i n i n g

g a s o l i n e , k e r o s e n e a n d l i g h t / m e d i u m d i e s el f r a c t i o n s t o o b t a i n( a) a h e a v y d i e s e l v a c u u m d i s t i ll a t e , b o i l i n g b e t w e e n 2 6 0 C a n d 3 0 0 C a t1 3 k P a , f o r p o t e n t i a l l u b r i c a t i n g o i l m a n u f a c t u r e ; t h i s w o u l d r e p r e s e n t

a l o w - v i s c o s i t y l u b r i c a t i n g o il ;(b ) a v a c u u m r e s i d u e , t o b e p r o c e s s e d i n a m a n n e r s i m i l a r t o t h e o n e u s e d f o r

S t u a r t r e s i d u e .T h e p r o c e s s i n g s t ep s a d o p t e d i n t h i s in v e s t i g a t i o n a r e o n e s w h i c h w o u l d

s e e m a p p r o p r i a t e f o r p r o c e s s i n g i n a r e f i n e r y . T h e f i rs t s t e p w a s t h e p r e p a r a -t i o n o f a v a c u u m d i s t i l l a te f r a c t i o n a n d a v a c u u m r e s i d u a l f r a c t i o n f r o m t h eR u n d l e s h a l e o i l. T h i s R u n d l e r e s i d u e a n d t h e S t u a r t r e s i d u e w e r e b o t h s o l v e n t -e x t r a c t e d u s i n g n o r m a l p e n t a n e , t o p r o v i d e a p e n t a n e - s o l u b l e e x t r a c t d e s c r i b e da s a m a l t e n e f r a c t i o n a n d a n a s p h a l t ic r e s i d u e . P e n t a n e e x t r a c t i o n i s n o tn o r m a l l y c a r r i e d o u t i n re f i n e ri e s ; p r o p a n e o r b u t a n e a r e u s u a l l y t h e p r e f e r r e dd e - a s p h a l ti n g s o l v e n t s . L a b o r a t o r y l i m i t a t i o n s w e r e th e r e a s o n p e n t a n e w a sc h o s e n , w i th t h e r e a l i s a t i o n t h a t a h i g h e r p r o p o r t i o n o f r e s i n o u s m a t e r i a lw o u l d b e e x t r a c t e d i n t h e m a l t S n e f r a c t i o n .

S i n c e s h a l e o i l i s o b t a i n e d b y p y r o l y s i s , s o m e t h e r m a l c r a c k i n g o f t h ek e r o g e n o c c u r s , s o t h a t s o m e o l e f i n i c m a t e r i a l i s p r e s e n t [ 1, 3 ]. T h e s e o l e f i n s ,b e i n g u n s a t u r a t e d , a r e q u i t e r e a c t iv e a n d m u s t b e r e m o v e d f r o m a n y l u b r i ca t -i n g o il f r a c t i o n t o e n s u r e i t s s ta b i l i ty . A n a l k y l a t i o n s t e p w a s t h e r e f o r e i n tr o -d u c e d t o in v e s t i g a t e w h e t h e r a l k y l a t i o n c o u l d r e d u c e t h e a m o u n t o f o l ef in sp r e s en t . A n y a l k y l a t i o n o c c u r r i n g s h o u l d i n c r e a s e t h e m o l e c u l a r w e i g h t , sa tu -r a t e a r o m a t i c s , i n t r o d u c e f u r t h e r s id e c h a i n s t o t h e c y c l i c s t r u c t u r e s a n dr e d u c e t h e a m o u n t o f h y d r o g e n r e q u i r e d i n th e s u b s e q u e n t h y d r o g e n a t i o n s t ep .F o r c o m p a r i s o n p u r p o s e s , e a c h s a m p l e w a s d i v i d ed i n t o t w o ; o n e s a m p l e b e i n ga l k y l a t e d a n d o n e n o t , a s s h o w n i n F i g s . 1 a n d 2.

F r o m t h e e a r l i e r w o r k o n b i t u m e n p r o d u c t i o n [8, 9 ], i t w a s a p p a r e n t t h a tb o t h s h a l e o i l s a m p l e s c o n t a i n e d a s u b s t a n t i a l a m o u n t o f w a x y m a t e r ia l . W a xw o u l d h a v e t o b e r e m o v e d f r o m a n y l u b r i c a t i n g o i l f r a c t i o n , s i n c e w a x i n-c r e as e s t h e p o u r p o i n t o f t h e p r o d u c t . S u c h w a x y m a t e r i a l m a y i t s e l f b ea s u i t a b l e f e e d s t o c k f o r a c r a c k i n g o p e r a t i o n .

F i n a l ly , h y d r o g e n a t i o n w a s n e c e s s a r y t o s t a b il i se a n y r e m a i n i n g o l ef in s a n df u r t h e r r e d u c e t h e a r o m a t i c c o n t e n t . S c h e m a t i c d i a g r a m s o f t h e p r o c e s s in g


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J .F . S tub ing to n e t a l . / Fu e l Pr oces s ing Tech no l . 37 (1994) 295 305 29 7Distillate (260 - 300 C @ 13 kPa)$

I BDAlkylation I

De-waxing I --"WAD WBD" -- [ De-waxingI DAD DBD

Hydrogenation I I H~,d rogena tionLube fraction HDA D Lube fraction HDBD

F i g . 1. P r o c e s s i n g s t e p s u s e d t o o b t a i n t h e f r a c t i o n s w i t h p o s s i b l e p o t e n t i a l f o r l u b r i c a t i n go i l p r o d u c t i o n f r o m t h e d i s t i l la t e f r o m R u n d l e s h a l e o i l.

Residue] Maltene extractionI

I] Alkylation ]AM BM

I] De-waxing ] ----WAM W B M -, -- De-waxingDAM DBM [

[ Hydrogen ation [ Hydrogen ationLube fraction HDAM Lube fraction HDBM

F i g . 2. P r o c e s s i n g s t e p s u s e d to o b t a i n t h e f r a c t i o n s w i t h p o s s i b l e p o t e n t i a l f o r l u b r i c a t i n go i l p r o d u c t i o n f r o m t h e d i s t i ll a t i o n r e s i d u e s o f S t u a r t a n d R u n d l e s h a l e o i ls .

u s e d a r e s h o w n i n F ig s . 1 a n d 2 , w h e r e t h e n o m e n c l a t u r e f o r i d e n t i f ic a t i o n o ft h e s a m p l e s i s g i v e n .

2 .1 . M a l t e n e e x t r a c t i o nA 1 0 0 g r e s i d u e p o r t i o n ( r e m a i n i n g a f t e r d i s t i l l a t i o n a t 3 00 C a n d 1 3 k P a , f o r

R u n d l e ) w a s r e f l u x e d w i t h 2 . 41 o f n - p e n t a n e a t 4 0 C f o r 12 h a n d t h e n s o a k e do v e r n i g h t . T h i s r e p r e s e n t s a h i g h e r r a t i o o f s o l v e n t t o r e s i d u e t h a n u s e d c o m m e r -c i a ll y , t o m a x i m i s e t h e e x t r a c t i o n y i e ld o f t h e p o t e n t i a l l u b r i c a t i n g o i l m a t e r i a lf o r t h i s l a b o r a t o r y i n v e s t i g a t i o n . P e n t a n e w a s c h o s e n a s t h e s o l v e n t t o a l l o we x t r a c t i o n a t a t m o s p h e r i c p r e s s u r e in t h e a v a i l a b l e l a b o r a t o r y a p p a r a t u s . T h er e a c t i o n m i x t u r e w a s f i lt e r e d t h r o u g h a fu n n e l , w a s h e d w i t h n - p e n t a n e a n dc o n c e n t r a t e d i n a r o t a r y v a c u u m e v a p o r a t o r t o c o l le c t t h e m a l t e n e s . T h e m a l -t e n e f r a c t i o n w a s d r i e d i n a v a c u u m o v e n , u n d e r n i t r o g e n a t m o s p h e r e a t lo wv a c u u m a n d 1 20 C f o r 4 5 h . S e v e r a l b a t c h e s w e r e e x t r a c t e d a n d t h e n h e a t e da n d c o m b i n e d t o g i v e a t o t a l w e i g h t o f a p p r o x i m a t e l y 1 00 0 g o f m a l t e n e s .


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29 8 J.F. Stubington et al./Fuel Processing Technol. 37 (1994) 295 3052.2. Alkylation

A 2 4 0 g s a m p l e o f m a l t e n e w a s d i s s o lv e d i n 2 4 0 m l o f n - h e p t a n e i n at h r e e - n e c k e d r o u n d - b o t t o m f l a sk u n d e r a n i t r o g e n a t m o s p h e r e . W e a d d e d5 .4 g o f a n h y d r o u s a l u m i n i u m c h l o r i d e a n d 1 .8 g o f m e t a l l i c a l u m i n i u mp o w d e r ( e q u i v a l e n t t o 3 % o f m a l t e n e a t a 3 :1 r a t i o o f a l u m i n i u m c h l o r id et o m e t a l l i c a l u m i n i u m ) a s a n a l k y l a t i o n c a t a l y s t t o t h e r e a c t i o n m i x t u r e ,m a i n t a i n e d a t 0 C b y i m m e r s i o n o f t h e f l a sk in a n i ce a n d w a t e r b a t h .T h e r e a c t i o n m i x t u r e w a s s t i r re d i n a n i t r o g e n a t m o s p h e r e a t 0 C fo r 2 h a n da t r o o m t e m p e r a t u r e f o r a f u r t h e r 6 - 8 h b e f o r e b e i n g a l l o w e d t o s t a n d f o ra f u r t h e r 1 8 h i n a n i n e r t a t m o s p h e r e . T h e r e a c t i o n m i x t u r e w a s f i lt e re d a n dt h e n d i s t i l l e d i n a r o t a r y v a c u u m e v a p o r a t o r t o c o l l e c t a l k y l a t e d p r o d u c ta n d r e c o v e r t h e n - h e p t a n e . T h e l a s t t r a c e s o f s o l v e n t w e r e e v a p o r a t e d i na v a c u u m o v e n u n d e r n i t r o g e n a t m o s p h e r e a n d p a r t i a l v a c u u m a t 120 C fo r1 9 h . U n d e r t h e s e c o n d i t io n s , t h e p r o d u c t h a d a t t a i n e d c o n s t a n t w e i g h t , s o n or e - d i s t i l la t i o n w a s n e c e s s a r y .

2.3. De-waxingB a t c h e s o f 30 g o f m a l t e n e s w e r e m i x e d w i t h 4 50 m l o f M I B K a n d t h e r e a c t i o n

m i x t u r e w a s w a r m e d t o a t e m p e r a t u r e o f 6 5 C f o r 3 0 m i n t o e n s u r e c o m p l e t ed i s so l u t io n . T h e r e a c t i o n m i x t u r e w a s t h e n a l l o w e d t o c o o l t o r o o m t e m p e r -a t u r e a n d t h e n t o - 17 C i n a c o l d b a t h o f m e t h a n o l f o r 2 h b e f o r e b e i n g f i l te r e d ,u s i n g a B u c h n e r f u n n e l t a k e n f r o m t h e f re e z er , to s e p a r a t e t h e w a x w h i c h w a st h e n w a s h e d w i t h c o l d ( - 1 7 C ) M I B K t o r e m o v e a l l d e - w a x e d m a t e r i a l . F i l-t r a t e a n d w a s h i n g s w e r e m i x e d a n d c o n c e n t r a t e d i n a r o t a r y v a c u u m e v a po -r a t o r t o c o l l e c t th e d e - w a x e d f r a c t io n . T h e w a x w a s d i s s o l v e d i n w a r m M I B Kf o r c o m p l e t e r e c o v e r y , c o l le c t e d in a n o t h e r f l a s k a n d c o n c e n t r a t e d i n a r o t a r yv a c u u m e v a p o r a t o r . T h e l a s t t r a c e s o f s o l v e n t w e r e r e m o v e d f r o m t h e d e - w a x e dm a t e r i a l u n d e r a l o w p a r t i a l p r e s s u r e n i t r o g e n a t m o s p h e r e a t 1 0 8 C f o r 19 h , t oc o n s t a n t w e i g h t .

2.4. HydrogenationT h e h y d r o g e n a t i o n o f e a c h o f t h e v a r i o u s f r a c t i o n s o f R u n d l e a n d S t u a r t

s h a l e o il w a s c a r r i e d o u t i n a P a r r - H y d r o g e n a t o r - 4 5 2 2 , a t a h y d r o g e n g a sp r e s s u r e o f 1 10 0 - 12 0 0 p si a n d a t e m p e r a t u r e o f 3 00 C , u s i n g a N i / M o c a t a l y s t(5 g N i / M o i n 3 m l C S 2 p e r 1 00 g o f s a m p l e ) f o r 6 h . T h e h y d r o g e n a t i n g c o n d i -t i o n s w e r e v e r y m i l d to a v o i d c r a c k i n g o f t h e s a m p l e s a n d t o s a f e g u a r d t h eh y d r o g e n a t i o n e q u i p m e n t . A b o u t 3 0 g o f a s a m p l e w a s t a k e n f o r e a c h h y d r o g e -n a t i o n a n d d i s s o lv e d in th e m i n i m u m q u a n t i t y o f n - h e p t a n e f o r c o m p l e t ed i s s o l u t i o n ( ~ 5 0 m l ). A f t e r h y d r o g e n a t i o n , t h e r e a c t i o n m i x t u r e w a s c o o l e d tor o o m t e m p e r a t u r e a n d t h e h y d r o g e n g a s p r e s s u r e w a s r e l e a s e d . T h e a u t o c l a v ew a s o p e n e d a n d w a s h e d w i t h n - h e p t a n e . T h e r e a c t i o n m i x t u r e w a s f i l t e r e d tor e m o v e c a t a l y s t a n d t h e n c o n c e n t r a t e d i n a r o t a r y v a c u u m e v a p o r a t o r t oc o l l e c t th e h y d r o g e n a t e d p r o d u c t . T h e l a s t t r a c e s o f s o l v e n t w e r e r e m o v e d b yd r y i n g i n a n o v e n a t 1 1 0 - 1 20 C o v e r n i g h t .


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J.F. Stubington et al./Fuel Processing Technol. 37 (1994) 295-305 299

8

~ o ~~ .~~ . ~

~ . ~~ ~~ " s

~ N

~ g

..~0

m

S

rl?


6/11

300 J . F . S t u b i n g t o n e t a l ./ F u e l P r o c e s s i n g T e c h n o l . 3 7 (1 9 94 ) 2 9 5 - 3 0 5One of the samples (Rundle HDBD) was submitted to a subsequent, longer

hydr ogen ati on under the same conditions for a fur ther 12 h, in an effort toobtain significant changes in the product.

3. ANALYSISFor comparison purposes, three lubricating oil base stocks derived frompetroleum crude were obtained and analys ed in par allel with t he proda ~:(s from

shale oil processing. The products were analysed for C, H and N on a Perkin-Elmer-240B elemental analyser. The elemental analysis data for the shale oilsamples are shown in Tables 1 and 2 and for the lubricating oil samples inTable 3. The nit rogen analyse s were all less tha n 1.8%, but the nitro genbalances were inconsistent, so these data are not presented.

The viscosity of the samples was determined by the method outlined in IP71/87, in most cases at 60 C and 100 C, since the samples were too viscous at40C. Only for Rundle de-waxed alkylated distillate could the viscosity bemeasured at 40 C. For a ll oth er samples, th e vi scosity at 40 C was obt aine d byextrapolation from determinations made at 60C and 100C, according toASTM D341-87 using the chart provided, so that the viscosity index could becal cul ate d by the met hod desc ribed in ASTM D2270-86 [10]. Insufficient mate-rial was produced to measure the pour points of the samples.

4. DISCUSSION4 . 1 . Y i e l d s

The first yield column in Tables 1 and 2 gives the pr oduct recovery da ta foreach of the individu al processing steps; wherea s the second yield column givesthe cumulative yield of the par ticular product from the sta rting material,which was topped shale oil in the case of the Rundle and atmospheri c distilla-tion residue in the case of Stuart. In view of the losses which inevitab lyoccurred during handling of the small amounts of material in the laboratory,the yield data are only approximate and the final product yields are thereforeconservative. Nevertheless, yields of ~13% for the distillate fraction and23% for the ma ltenes are significantly greater than the yield of lubricatingoil fractions from the Middle Eastern crudes usually used for lubricating oilproduction.

4 .2 . E l e m e n t a l a n a l y s i sThe most reliable index of change is provided by the ratio of hydrogen tocarbon, calcul ated from the eleme ntal analysis and sho wn in Tables I and 2. Ingeneral, the e lemental analy sis was not sig nificantly changed by the alkyla-tion, suggesting that the alkylation step was not effective.


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J . F . S t u b i n g t o n et a l . / F u e l P r o c e ss i n g T e c h n o l . 3 7 ( 1 99 4 ) 2 9 5 - 3 0 5 3 0 1

~ o~ o~

~ ~ ?

~D

O ~

: z


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30 2 J.F. Stubington et al./Fuel Processing Technol. 37 (1994) 295 305T A B L E 3E l e m e n t a l a na l y s e s a n d v i s c os i t ie s o f t he s t a nd a r d l ub r i c a t i ng o i l ba s e s t oc ksS a mpl e C H C / H H / C M e a s u r e d M e a s u r e d V i s c os i t y(wt .%) (wt .%) (by wt . ) (mole v i sco s i ty v i scos i ty indexrat io ) at 40 C at 100 C(cSt) (cSt)ALO R-300S N 87.2 13.2 6.60 0.91 59.3 7.81 95ALO R-500S N 86.8 13.1 6.60 0.91 91.3 10.57 98ALO R-160S N 87.9 13.2 6.68 0.90 567.5 34.8 95

D e - w a x i n g d e c r e a s e d t h e H / C r a t i o o f t h e R u n d l e d i s t i l l a t e s l ig h t l y , s i n c e th ew a x w a s h i g h e r i n h y d r o g e n . T h e w a x e s f r o m t h e d i s t i l l a te h a d a H / C m o l er a t i o o f 1 .0 2 -1 .0 4 , i n d i c a t i n g p a r a f f i n s ( - C H 2 - f o r w h i c h H / C ~ 1), h i g h l y s u i t-a b l e as a c a t a l y t i c c r a c k i n g f e e d s t o c k o r f or l o c a l in d u s t r i e s u s i n g p e t r o l e u mw a x . H o w e v e r , t h e w a x e s f r o m t h e m a l t e n e s w e r e n o t s t r a i g h t - c h a i n s t r u c -t u r e s , s i n c e t h e i r H / C r a t i o s w e r e l es s t h a n 1. F u r t h e r m o r e , r e m o v a l o f t h ew a x e s f r o m t h e m a l t e n e s d i d n o t s i g n i f i c a n t ly c h a n g e t h e i r H / C r a t io s , s u g g e s t -i n g t h a t t h i s s t e p d id n o t a f f e c t th e r a t i o o f p a r a f f in i c to a r o m a t i c s t r u c t u r e s i nt h e m a l t e n e p r o d u c t s .

T h e e l e m e n t a l a n a l y s e s i n d i c a t e d t h a t t h e in i t ia l h y d r o g e n a t i o n s t ep w a s n o te f f e c t iv e fo r th e R u n d l e s a m p l e s , so t h a t m o r e s e v e r e o p e r a t i n g c o n d i t i o n sw o u l d b e n e c e s s a r y f o r e f f ec t iv e h y d r o g e n a t i o n . S m a l l i n c r e a s e s i n th e H / Cr a t i o w e r e o b t a i n e d f r o m th e i n i t i a l h y d r o g e n a t i o n o f t h e S t u a r t m a l t e n e s a n df r o m p r o l o n g e d h y d r o g e n a t i o n o f t h e R u n d l e d e - w a x e d d i s t i l l a te s a m p l e . T h eH / C r a t i o s f o r al l o f t h e f i n a l h y d r o g e n a t e d p r o d u c t s f r o m t h i s s h a l e o i lp r o c e s s i n g w e r e s i g n i f i c a n t l y l o w e r t h a n f o r t h e p e t r o l e u m - d e r i v e d o i l s( T a b l e 3), s u g g e s t i n g a d e fi c i e n c y o f h y d r o g e n e v e n a f t e r h y d r o g e n a t i o n f o ra l o n g e r t i m e .

4.3. ViscosityM o s t o f t h e s h a l e o i l f r a c t i o n s , a l t h o u g h b o i l in g i n t h e s a m e r a n g e a s

p e t r o l e u m - d e r i v e d l u b r i c a t i o n o i l s, w e r e t o o v i sc o u s t o m e a s u r e t h e i r v i s c o s i tya t t h e s t a n d a r d 4 0 C . T h e r e f o r e , v i s c o s i t y m e a s u r e m e n t s w e r e m a d e a t 60 Ca n d 1 00 C a n d t h e v i s c o s i t y a t 4 0 C w a s e s t i m a t e d b y e x t r a p o l a t i o n ( e x c e p t f o rR u n d l e D A D ) . T h e v i s c o s i ty a t 4 0 C w a s n e e d e d t o c a l c u l a t e t h e v i s c o s i t yi n d ex , w h i c h i s a m e a s u r e o f t h e e f f e c t o f c h a n g i n g t e m p e r a t u r e o n t h e v i s co s -i ty . T h e h i g h e r t h e v i s c o s i t y i n d e x t h e l e s s i s t h e d r o p i n v i s c o s i t y f o r a g i v e nt e m p e r a t u r e i n c r e a s e a n d h e n c e t h e b e t t e r t h e p e r f o r m a n c e o f t h e o il . S i n c ev i s c o s i t y i n d e x i s v e r y s e n s i t i v e t o t h e v a l u e a t 40 C , th i s e x t r a p o l a t i o ni n t r o d u c e d s i g n i fi c a n t e r r o r s a n d t h e v a l u e s o f v i s c o s i t y i n d e x g i v e n i n T a b l e s 1a n d 2 m a y h a v e e r r o r s a s h i g h a s + 10.

A l k y l a t i o n s o m e t i m e s i n c r e a s e d a n d s o m e t i m e s d e c r e a se d t h e m e a s u r e dv i s c o s i t y s l ig h t l y , s u g g e s t i n g t h a t i t d i d c a u s e s o m e r e - a r r a n g e m e n t o f t h e


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J.F. Stub ingt on et al./Fu el Processing Technol. 37 (1994) 295 305 303molecular structure even though no change in elemental analysis was ob-served. However, within the accu racy of determ ination, alkyla tion did notaffect the viscosity index of the final hydrogenated products. Hydrogenationdecreased the measure d viscosity for all samples, suggesting tha t it was effec-tive to a small degree in changing the molecular structure, even when nochange in elemental composition was detected.

For the Rundle distillate products, the measured viscosities were less thanthose of the petroleum-der ived lubricating oil base stocks. However, the phys-ical appeara nce of these samples at room tempe ratu re was of a much moreviscous fluid and onl y one sample (DAD) was fluid enou gh for its visco sity to bemeasured at 40C. This phenomenon may be explained by the formation ofa suspension of immiscibile microcrystalline components at lower temper-atures, forming a slurry-type material. It seems quite possible that furtherseparation may be necessary to obtain a potential lubricating oil base stockfrom the distillate fraction. The yield of distillate pr oduct boiling in thelubricating oil range is quite high, so a more rigorous solvent extractionprocess may still be justified. The estimated viscosity index of 100 for hydro-genated de-waxed Rundle distillate provides further justification for con-tinued work, when compared to the values of 95 98 for the petr oleum-derivedbase stocks.

The viscosities of the ma ltene samples from both Rundle and St uart shaleoils were in the same range as those for the petroleum- derived base stocks. Theestimated viscosity indices for hydrogenated residue products from Rundleshale oil (77) were too low for them to be viewed as potential sources oflubricating oil, but the estimated viscosity indices for hydrogenated residueprodu cts from Stu ar t shal e oil (89 90) were closer to those of the pet roleum-derived base stocks.

5. CONCLUSIONSRelative ly high yields of potentia l lubri cating oil base stock material were

obtained for both the distillate and maltene fractions from Rundle and Stuartshale oils in comparison with yields from crude petroleum.

The alkylation step did not significantly change the elemental composi-tion of the samples and would not seem warr ante d in any scheme to producelubricating oils. De-waxing removed paraffins from the distillate samples,but removed mixed structures from the residue samples; and only one ofthe products became liquid at room temperature. In most cases, the initialhydrogenation step was not long enough and/or not severe enough to changesignificantly the elemental composition. Even after the longer hydroge-nation, the H/C ratio was not as high as for the petroleum-der ived lubrica tingoil base stocks and it must be concluded tha t the chem ical make-up of theshale oil products is different from the petroleum products. However, thedifferent chemical structure for the shale oil products does not precludethem from consideration as a potential source of lubricating oil.


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304 J.F. Stubington et al./Fuel Processing Technol. 37 (1994) 295-305Viscosity measurements suggest the Rundle distillate has the potential to

produce low-viscosity lubrica ting oil base stock, but the products from Rundleand Stuar t residues are less prospective. Furth er sepa ration via solvent extrac-tion of the Rundle distillate ma y be warrant ed to remove the presume d micro-crystalline phase causing high viscosity at ambient temperature. A detailedstru ctur al analysis of the products will be undert ake n to identify the struc-tures present.

ACKNOWLEDGEMENTThe financial support of the Ener gy Research and Developme nt Corpor ation

is acknowledged as is the support of Southern Pacific Petroleum N/L, whoprovided the shale oil samples, and the Australian Lubricating Oil Refinery,who provided the lu bricati ng oil samples. The con tribu tion of Dr. Jacky Fahyand Dr. Suresh Raj in the experimental program is also acknowledged.

NOMENCLATUREADALOR-300SNALOR-500SNALOR-160BSAMBDBMDADDAMDBDDB MHDADHDAMHDBDHDBMHyd. HDBDWADWAMWBDWB M

alkylated distillatelubricating oil base stocklubricating oil base stocklubricating oil base stockalkylated maltenesdistillatemaltenesde-waxed alkylate d distillatede-waxed alkylated maltenesde-waxed distillatede-waxed malteneshydrogenated de-waxed alkylated distillatehydrogenated de-waxed alkylated malteneshydrogenated de-waxed distillatehydrogenated de-waxed maltenesprolonged hydrogenated de-waxed distillatewax ex alkylated distillatewax ex alkylated malteneswax ex distillatewax ex maltenes

REFERENCESNguyen, V.D., 1990. Yields and chemical characteristics of products from fluidized bedsteam retorting of Condor and Stuart oil shales; effect of pyrolysis temperature. Fuel,69: 368-376.


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Charlton, B.G., 1988. Combustion kinetics of some Australian spent oil shales between600C and 900 C. Fuel, 67: 1361.Regtop, R.A., Crisp, P.T. and Ellis, J ., 1982. Chemical characterization of shale oil fromRundle, Queensland. Fuel, 61: 1855192.Bett, G., Harvey, T.G., Matheson, T.W. and Pratt, K .C., 1983. Determination of polarcompound in Rundle shale oil . Fuel, 62: 144551454.Cook, E.W., 1974. Oil -shale technology in the USA. Fuel, 53: 1466151.Harada, K., 1991. Research and development of oil shale in J apan. Fuel, 70: 133061335.Nguyen, V.D., Duffy, G.J . and Charlton, B.G., 1990. Comparison between model predic-tions and performance of process development units for oil shale processing. Fuel, 69:115881163.Barrett, D., Sambi, T. and Sergeant, G.D., 1990. Properties of vacuum residual fractionsfrom Austral ian shale oils compared with a petroleum bitumen. Fuel, 69: 2677269.Sergeant, G.D., Barrett, D. and Sambi, T., May 1990. Bitumen production from shale oilresidues. NERDDP EG90/902, 39 pp.Annual book of ASTM standards, 1990. Petroleum Products, Lubricants and FossilFuels. D2270-86, Vol. 05.02: 1044105.Institute of Petroleum, 1991. Standard methods for analysis and testing of petroleum andrelated products. London, Vol. 1: IP 71/87.

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