BITUMEN and HEAVY OILS: INFLUENCE OF PITCH PROPERTIES

8/14/2019 BITUMEN and HEAVY OILS: INFLUENCE OF PITCH PROPERTIES

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PITCH RESIDUES FKON UPGRADING O F BITUMEN A N I ) HEAVY O I L S A S ADDITIVES I N C O K E M A K I W G :INFLUENCE OF PITCH PROPERTIESK . Be l in k o , L.A. C ia v a g l i a , B . N . Nandi and J . M . Denis ,

Energy Research Lab ora tor iesDepartment of Energy, Mines and Pesources ,

c / o 5 5 5 B oo th S t r e e t , O t ta wa , O n t a r i o K 1 A O G 1Canada Centre f o r Min e ra l a n d E ne rg y Technology,

INTRODUCTIONImpe n din g s h o r ta g e s o f good c o k in g c o a l s th ro u g h ou t th e wo rld h a v e

prompted a s e r i e s o f i n v e s t i g a t i o n s a t CANMET (Canada Ce n t r e f o r Mineral and EnergyT ec hn ol og y) i n t o t h e u t i l i z a t i o n o f w e s t e r n C an ad ia n m ar g i n al c o k i ng c o a l s i n t h ep r o d u c t i o n of m e t a l l u r g i c a l g r a d e c o ke . One p o s s i b l e way t o do t h i s i s t o addr e s i J u a l p i t c h f ro m thermal h y d r o c r a r k i n g of b i tu m en a nd hea vy o i l s t o s u c h c o a l s( 1 ) . T h i s p i t c h h a s be en f ou nd t o b e a n e x c e l l e n t a d d i t i v e f o r u p - g ra di n g lowf l u i d , low v o l a t i l e , i n e r t - m ac e r al r i c h c o a l s . The p i t c h a c t s a s a f l u i d i t y -e n ha n ci n g a g e nt , a nd by i n t e r a c t i n g w i th t h e v i t r i n i t e o f t h e c o a l , a ugm en ts t h es u p p l y o f r e a c t i v e c a r b on n e c es s a r y f o r b o n d in g to g e th e r of i n e r t m a c e ra l s.

The p u r p os e o f t h i s p u b l i c a t i o n is t o ad d f u r t h e r i n s i g h t i n t o t h e r o l eo f p i t c h i n c a r b o n i z a t i o n o f c o a l / p i t c h b l e n d s . P i t c h e s d er i v e d f ro m t h er m alh y d ro c r a c k in g o f b i tu men a t d i f f e r e n t d eg re es of s e v e r i t i e s were u t i l i z e d f o r t h i sp u r p o s e . T h i s p r o v i d e d a means o f a s s r s s i n g t h e p r o p e r t i e s of t h e pi t c h e s i n t h ec a r b o n i z a t i o n p r o c es s w i t h o u t c h a n g i ng t h e b a s i c c h e m ic a l n a t u r e o f t h e p a r e n tm a t e r i a l .

EXPERIMENTAL

The p r o p e r t i e s o f t h e p i t c h e s d e r i v ed f rom t h er m al h y d r o c r a ck i n g o fA t h ab a sc a b it um en u n d e r v a r i o u s o p e r a t i n g c o n d i t i o n s a r e g i v e n i n Ta b l e 1 . Thesefour p i t c h e s were p r od u ce d u n de r d i f f e r e n t d e g r e e s of s e v e r i t y d u r i n g t h e p r oc e ssA b e i ng c h a r a c t e r i s t i c o f p i t c h o b t a i n e d u nd er r e l a t i v e l y m il d c o n d i t i o n s a nd D ,o f p i t c h o bt ai ne d a t hi gh s e v e r i t i e s . A r r l a t i o n was f ou nd t o e x i s t be tw ce n t h ed e g r ee o f s e v e r i t y d u r i n g h y d r oc r a c ki n g and t h e v a ri o us p r o p e r t i e s l i s t e d i nT a h l e 1 (e .g . CCR, a r o m a t i c i t y , s o f t e n i n g p o i n t) .

TABLE 1

P h y s i c a l an d Ch em ic al P r o p e r t i e s o f P i t c h e s

Vola t i l e matter %Ash %S o f t e n i n g t e m p e r a t u r e O CCo nra ds o n c a rb o n re s i d u e %S p e c i fi c g r a v i t yBenzene- inso lub les*A s p h a l t e n e s %H / CS u l p h u r %Aro ma t ic i ty * * %--

A73.11 .85034.71.10

2.637.2

1 . 3 25 .58

-3 8 . 2

-64.82 . 3

9 542.21.124.2

4 4 . 61 . 1 55.6:

-49.4

tchC

53.53 .2

50.711 .648.1

1051 . 1 6

1 . 0 96.335 6 .3

_ _ _D44 .6-5 . 8

13564.620.655.2

1 .24

0 .944 .856 9 .8-_* A s h - f r e e b a s i s , ** 1% NM R a n a l y s i s

13 8


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The coal used was a w e s t e r n C an a di a n, l ow f l u i d , h i g h r a n k b i t u m i n o u sc o a l h a v i ng a r e l a t i v e l y h i g h c o n c e n t r a t i o n o f i n e r t m a c er a ls .a n d P et r o g r a p hi c a n a l y s e s of t h i s c o a l a r e g iv e n i n T a bl e 2 . P r o x i m a t e , u l t i m a t e

TABLE 2P r o p e r t i e s o f t h e C oa l

P r o x im a t e A n a l y s i s ( d r y b a s i s )Ash % 9 .8V o l a t i l e m a t t e r % 21.2Fixed Carbon % 69.0

U l t i m a t e A n a l y s i sCarbon % 78.9Hydrogen % 4 . 3Su lphur % 0 . 8N i t r o g e n % 1 . 3Oxygen (by diff . ) % 4.9Ash % 9.8

P e t r o g r a p h i c A n a l y s i sV i r i n i t e v o l . % 51 . 8Semi-f u s i n i e v o l . % 34.2F u s i n i e v o l . % 1 1 . 2M ic r in i t e v o l . % 2 . 6E x i n i t e v o l . % 0 .2

1.17R Oean r e f l e c t a n c e i n o i l ,C o a l f p i t c h b l e n d s w i th v a r y i n g p i t c h c o n c e n t r a t i o n s we re p r e p a r e d a nd

t h e i r f l u i d i t i e s d e te r mi n ed b y means of a G i e s e l e r p l a s t o m e t e r . The f l u i d i t i e s oft h e v a r i o u s b l en d s a r e r e p o r t e d i n T ab le 3 .of p i t c h wh ich c a n p o t e n t i a l l y i n t e r a c t wi t h t h e c o a l d u r i n g c a r b o n i z at i o n , C p , i sa l s o g i v e n i n T ab le 3 .

A v a l u e r e p r e s e n t i n g t h e c o n c e n t r a ti o nCp was c a l c u l a t e d o n t h e f o l l o w in g b a s i s :

where CC R i s t h e C o nr ad so n ca r b o n r e s i d u e ( 2) a n d a p p r o xi m a te s t h e c o n t r i b u t i o n o fc a r b on a c e o us m a t e r i a l made by t h e p i t c h t o t h e b l en d d u r i n g c a r b o n i z a t i o n .

The v a r i o u s c o a l l p i t c h b l e n d s w e re c a r b o n i z e d u s i n g a c a n i s t e r c o ki ngt echn iqu deve loped a t CANMET ( 3 ) . T he b l e nd s were packed t o a b u l k d e n s i t y o f8 01 kg/m i n t o p e r fo r a t ed t i n p l a t e c a n i s t e r s 29. 3 cm long and 1 .6 cm i n diam ete r .Twenty ca ns , each con t a i n in g a d i f f e r e n t b l e n d w er e s i de - ch a rg e d i n t o CANMET'S250-kg moveable w a l l coke oven .

5 .

The r e l a t i v e s t r e n g t h s o f t h e c o ke s p ro d uc ed f r om t h e c a n i s t e r t e s t weredetermined by a small sample t umble r t e s t deve loped by Bi tuminous Coa l Resea rch(BCR) (4) and ar e rep or te d i n Table 3 . T he se s t r e n g t h i n d i c e s are a measure ofs i z e r e d u c t i o n i n t um bl ed c o ke p a r t i c l e s and t h e r e f o r e a l a r g e i n d e x c o r r e s p o nd st o a weak coke.

O p t i c a l e x a m i n a t i o n s o f t h e v a r i o u s c o k es w e re made w i t h a L e i t z r e f l e c -t e d l i g h t m ic ro sc op e u s i n g an o i l i mm er si on l e n s . The micrographs were t ak en a t6OOX m a g n i f i c a t i o n u s i n g p a r t i a l l y c r o s s e d n i c o l s .

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TABLE 3C a r b o n i z a t i o n D a ta f o r C o al P i t c h B l e n d s

37039.0

9 . 1

P i t c h Ac o n t r i b u t i o n o f c a r b o nf r o m p i t c h . CpF l u i d i t y of b l e n dBCR* s t r e n g t h i n d e x

P i t c h BC o n t r i b u t i o n o f c a r h o n

f rom p i t ch , CpF l u i d i t y o f b l e n dBCR* s t re n g th in de x

P i t c h CC o n t r i b u t i o n o f c a r b o n

f rom p i t ch , CF l u i d i t y o f b legdBCR* s t re ng th in de x

P i t c h DC o n t r i b u t i o n o f c a r b o n

f r o m p i t c h , CpF l u i d i t y o f b l e n dBCR* s t r e n g t h i n d ex

40040 . 3

10.4

%ddlmin

%ddlmin

%ddlmin

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N i lN / A * *

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2.11 . 553.8

2 . 61.1

52.7

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57.8

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2.46 . 1

36.4

3 . 35 . 735.3

4 . 15.0

36.7

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4 . 17 . 134.5

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n Blend w t %'x-pi-

7.1 I 8.2

* B i tu m in o us C o al K e s ea r r h I n c . , P i t t s b u r g h , P . A .** A non-agglomerated ch ar was producedRESULTS AN D DISCUSSION

A pho tograph showing t w o r e p r e s e n ta t i v e c o ke s f ro m t h e c a n i s t e r t e s t i sshown i n F i g . 1. The coke shown a t t h e t o p was produced f rom coa l wi th n o p i t c ha dd i t i v e and was poo r ly agg lomera t ed . The coke a t t h e bo t tom was agg lomera t ed andh a r d a n d was t y p i c a l o f cokes p roduced f rom co a l l p i t ch b l e nd s . T he fo rmer cokec o u l d n o t b e e v a l u a t e d by t h e B C R tumbler t e s t because of i t s non-agglomeratedc h a r a c t e r . The s t r e n g t h i n d i c e s o f t h e c o k e s p r od u ce d f ro m c o a l l p i t c h b l e n d s a r eg i v e n i n T a h le 3 .

Th e s t r e n g t h s o f t h e c o k es p ro d uc e d fro m b l e n d s c o n t a i n i n g p i t c h A andp i t c h B were not f o u n d t o v a ry s i g n i f i c a n t l y f o r p i t c h c o n c e n t r a ti o n s ab ov e 5 % . Ont h e o t h e r h a nd . a d d i t i o n s of more t ha n 1 0% p i t r h i n r o a l l p i t r h C a n d c o a l l p i t c h I)b l e n d s w er e f ou nd t o b e d e t r i m e n t a l t o c ok e s t r c n g t h . Thr i n f l u e n c e o f ? i t c t lc o n c e n t r a t i o n on coke s t r en g t h was t he re fo re more p ronounced f o r p i t c h o b t a i n e dfr om h i g h s e v e r i t y t h e r m a l h y d r o c r a c ki n g r u n s . I t would h e d i f f i c u l t t o p re d i c ta n e x a c t op tim um p i t c h c o n c e n t r a t i o n h a s c d s o l e l y o n t h e r e s u l t s r e p o r te d i nT ab le 4 f o r m a l l p i t c h D b l e n d s .

C n a l l p i t c h h l c n d s hav ing C p v a l u p s i n e x c s s s o f a b o u t 7 % produced cokeso f p r o g r r s s i v e l y w ea ke r s t r p n g r h s . The Conradson carhon re si du c ( C C R ) c o n t e n t s o fp i t c h e s A a n d H w er e s u f f i c i p n t l y l o w t o p e r m it a d d i t i o n s o f up t o 1 h X p i t c h t o t h eCoal wi thot i t C P valut2s o f t he hl en d e x c e d i n g 77 , . T hi s Would accoun t fo r t h e l a ckof a minimum i n IlCR s t r e n g t h index f n r cokes produced f rom blend s co nt a i ni ng pi tc h

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A a n d p i t c h B w i t h i n t h e c o n c e n t ra t i o n r a n ge i n v e s t i g a t e d .F l u i d i t y d a t a f o r t h e v a r i o u s b l e n d s a r e s um mari zed i n T a bl e 3.

m lr ke d i n c r e a s e i n t h e f l u i d i t y o f t h e bl e n d s w a s o b s er v ed f o r p i t c h c o n c e n t r a t i o n sg r e a t e r t h a n LO%.n ou nc ed f o r p i t c h o b t a i n e d f r o m h i g h s e v e r i t y t h e r m a l hy d r o c r ac k i n g r u n s .p e rh ap s s u g ge s t s t h a t t h e r e i s a b e t t e r i n t e r a c t i o n b et we en p i t c h and t h e v i t r i n i t eo f t h e c o a l i n c a s e s w he re t h e p i t c h was t r e a t e d u n d er more s e v e r e c o n d i t i o n sduring thermal hydrocracking.is d i r e c t l y r e l a t e d t o t h e d e g r ee of s e v e r i t y d u r i n g t h e r m al h y dr o cr a ck i ng .i n t e r a c t i o n between t h e p i t c h and t h e v i t r i n i t e may t h e r e f o r e b e r e l a t e d t o t hea r o m a t i c i t y of t h e p i t c h :

A

The i n c r e a s e i n f l u i d i t y w a s gen e ra l ly found to be more p ro -Th i s

I t i s e v i d e n t f r o m T a b l e 1 t h a t p i t c h a r o m a t i c i t yThe

Based on some o f t h e a rg u me n ts p r e s e n t e d a b o v e , t h e f o l l o w i n g r e l a t i o n -s h i p was f o un d t o b e c o n s i s t e n t w i t h t h e d a t a i n T a bl e 3:

0 . 9 7BCR s t r e n g t h i nd ex = 26.47 + 1 . 7 5 Cp exp -*A3,2F, 1.5 5 CP 5 10 .4 2)Where Cp i s d e f i ne d a c c or d i n g t o E q u at i on l ) , A i s t h e a r o m a t i c i t y o f p i t c h d e t e r -mined by l 3 C NMR and F i s t h e f l u i d i t y of t h e c o a l / p i t c h b le nd .p l o t t e d i n F i g. 2 an d w a s f o un d t o h av e a c o e f f i c i e n t o f c o r r e l a t i o n of 0.89.Equa t ion 2) i s

A cc o rd i ng t o E q u a t i on 2 ) , t h e BCR s t re ng th in dex of a coke p roduced f roma c o a l / p i t c h b le nd i s no t on ly dependen t on t h e va lue o f Cp, bu t a l s o on t h ef l u i d i t y o f t h e b le nd . Low values of C p i n t h e b le nd a p pe ar t o be d e s i r a b l e i na c h i ev i n g good c o ke s t r e n g t h p r ov i de d t h e f l u i d i t y o f t h e b l e nd i s s u f f i c i e n t l yh i g h t o make t h e e x p o n e n t i a l term in t h e e q u a t i o n a pp r oa c h u n i t y .e n t i a l t er m h a s a p pr o ac h ed u n i t y , a d d i t i o n a l i n c r e a s e s i n Cp may o n l y c o n t r i b u t e t oa d e t e r i o r a t i o n i n co ke s t r e n g t h . The i n t e r - r e l a t i o n s h i p b et we en Cp a nd f l u i d i t yborne ou t by Equa t ion 2 ) emphasizes t h e n eed f o r c o n t r o l l e d f l u i d i t y i n e n s ur i n g au ni fo rm a nd e f f i c i e n t d i s t r i b u t i o n o f t h e b i n d i n g material t h r ou g ho u t t h e c o a ld u r i n g c a r b o n i z a t i o n . T h i s i s d e mo n s tr a te d , f o r i n s t a n c e , i n t h e c a s e of 5%a d d i t i o n o f p i t c h D t o t h e c o a l , T a bl e 3. Al though th e Cp va l ue was re l a t i ve lyh igh , low f l u i d i t y p r ev e nt e d p r op e r d i s t r i b u t i o n of t h e b i n d in g material in t h ec o a l d u r i n g c a r b o n i z a t i o n ; c o n s e qu e n t l y, a weak coke w a s produced.

Once t h e expon-

I n o r d e r t o c o nf i r m t h i s d ep en de nc e on f l u i d i t y , a series o f m i c r o s c o p i cThe coke pro-xamina t ions w a s made on t he cokes p roduced f rom the can i s t e r t e s t .

duced from the c oa l wi th no p i t c h a d d i t i v e was f ou nd t o b e p o o r l y bo nd ed .m a c e r al s w er e s e g r e g a t e d w i t h i n t h e c o ke s t r u c t u r e w i t h l i t t l e or no b i n d i n gma t e r i a l su r round ing them (F ig . 3).q u a l i t i e s d e p e n d i n g on v a l u e s o f Cp a nd f l u i d i t y . T h re e s p e c i f i c c a s e s w e r e chosent o d e m o n st r a t e t h i s d ep en de nc e: ( i ) c o a l + 5% p i t c h D, ( i i ) c oa l + 10%p i t c h D an d( i i i ) c oa l + 16%p i t c h D.

I n e r tCoa l /p i t ch b lends p roduced cokes o f va ry i ng

I n c a se ( i ) , c o a l + 5% p i t c h D, some deg ree of bondin g was ob se rv edb et we en i n e r t ma c e r al s , b u t t h e bo n di n g was g e n e r a l l y d i s c o n t i n u o u s a n d s p o r a d i c .Th i s i s e x e m pl i f i e d f o r i n s t a n c e i n F i g . 4 . I t i s n o te w or t hy t h a t f o r b l e n d sh av in g s i m i l a r Cp v a l u e s bu t hi g h e r f l u i d i t i e s , e .g . c o a l + 1 0% p i t c h A , bondingwas found t o be cons ide rab ly more un i fo rm than th a t shown in F ig . 4. The d i f f e r -e nc e i n b o nd in g ca n t h e r e f o r e b e a t t r i b u t e d t o t he f l u i d i t y of t h e r e s p e c t i v eb l e n d s .

The coke p roduced f rom cas e ( i i ) , co a l + 10% p i t c h D, w a s f o u n d t oe x h i b i t e x c e l l e n t b o nd i ng . The b i n d i n g m a t e r i a l w a s un i fo rmly and con t inuous lyd i s t r i b u t e d t h r o u g ho u t t h e c ok e a nd t h e i n e r t m a ce r a l s we re e mbedded w i t h i n t h ecoke matrix, Fig . 5. T he se o b s e r v a t i o n s w er e c o n s i s t e n t wi t h t h e r e l a t i v e l y goodBCR s t r e n g t h i nd e x o b t a in e d f o r t h i s co ke.

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The d e t e r i o r a t i o n i n c o ke s t r e n g t h o bs e rv ed f o r c as e ( i i i ) , c oa l + 16%p i t c h D, was a t t r i b u t e d t o t h e d ev el op me nt o f m i cr o -c r ac k s w i t h i n t h e c o k e s t r u c -tu re , F ig . 6 . The mechanism by which the se c rack s fo rm i s n o t w e l l u n d er s t oo d ,b u t c o ul d p e r ha p s r e s u l t f r o m a n e x c e s s of b i n d i ng m a t e r i a l b et we en t h e i n e r tm a c e r al s of t h e c o a l , t h e r e by w ea ke ni ng th e o v e r a l l s t r u c t u r e .

From th e th r e e c a s e s c o n s id e re d , i t i s e v i d e n t t h a t c ok e s t r e n g t h c an b ec o r r e l a t e d t o t h e m i c. r o- s tr u ct u re o f t h e cokes . T h e c o k e q u a l i t y a p p e a r s to b e ac o mp le x fu n c t io n of t h e a mo un t o f p i t c h a d d ed , th e ph y s ico -c h emic a l p r o p e r t i e s o ft h e p i t c h and t h e f l u i d i t y of t h e c o a l / p i t c h b l en d .

I t s h o ul d b e em p ha s iz e d t h a t t h e a r gu m en t s p r e s e n t e d i n t h i s p a pe r a p p l ys p e c i f i c a l l y t o i n e r t - m a c e r a l r i c h , low f l u i d , h i g h r a nk c o a l s . E q ua t io n 2 ) h a ss o f a r only he en t e s t e d f o r t h i s p a r t i c u l a r t yp e o f c o a l . I t i s p o s s i bl e t h a to t h e r c o a l s may y i e l d r e s u l t s t h a t do n o t c on fo rm e x a c t l y t o t h i s e q u a ti o n . F ori n s t a n c e , t h e c o a l u se d i n t h i s work had no i n h e r e n t f l u i d i t y , a nd c on s e q ue n t l y at er m f o r t he f l u i d i t y of t h e c oa l i t s e l f d oes not a p p e a r in th e e q u a t i o n . HoweverEqua t ion 2 ) d oe s d e m o n st r a t e t h e s t r o n g i n t e r - r e l a t i o n s h i p b et w ee n t h e c o n t r i b u t i o nof b i n d i ng m a t e r i a l m ade by t h e p i t c h a nd t h e f l u i d i t y of t h e b l e n d .

CONCLUSIONS

High rank c oa ls f rom wes te r n Canada which a re r i c h i n i n e r t m ac er al s,g e n e r a l l y r e q u i r e a p i t c h a d d i t i v e t o p ro du ce m e t a l l u r g i c a l g r a de c o ke . P i t c hc o n c e n t r a t io n i n t h e c o a l l p i t c h b l e nd d i c t a t e s b ot h t h e amount of b i n d i n g m a t e r i a lma d e a v a i l a h le t n t h e c o a l a nd t h e f l u i d i t y of t h e b l en d . B ot h t h e s e p a r a m et e r sdepend on t h e ph y si c o- c he m ic al p r o p e r t i e s o f t h e p i t c h a nd on t h e e x t e n t of i n t e r -a c t i o n between t h e p i t c h a n d t h e c o a l .

I n o r d e r t o p ro d u c e good q u a l i ty c o k e f rom a c o a l / p i t c h b l e n d , t h e b l en dmust p o ss es s s u f f i c i e n t f l u i d i t y t o e n su r e a u n if o rm an d c o nt i n u o u s d i s t r i b u t i o nof b i n d i n g m a t e r i a l t h r ou g h ou t t h e c o a l . I n e r t m a c e r al s of t h e c a 1 must b ea d e q u a t e ly we t t e d a n d b on de d t o g e th e r .p i t c h i s a dd ed i n s u F f i c i e n t amount t o g e n e r a t e a c o n t r o l l e d f l u i d i t y w i t h enoughb i n d i n g m a t e r i a l t o a g g l o m e r a t e t h e co ke . I f a dd ed i n l a r g e a m ou n ts , t h e p i t c h c anh av e d e l e t e r i o u s e f f e c t s on t h e r es u l t an t coke . The rea son why too much p i tc hw ea ke ns t h e s t r u c t u r e i s n o t w e l l u nd e r s t oo d , b u t a p p e a r s t o be r e l a t e d t o t h edevelopment o f m i c r oc r a ck s w i t h i n t h e c o ke m a t r i x .

9 .Optimum coke s t r en g t h i s ach ieved when

ACKNOWLEDGEMENTS

h i s

1.

I .3 .

4 .

T h e a u th o rs w i s h t o t h a n k B . H . M o f f a t t an d S. E. N ix on f o r t h e i r t e c h n i c a la s s i s t a n c e d u r i n g t h e c o u r se of t h i s work. Thanks a r e a l so due to W . Gardiner ands t a f f f o r t h e i r a s s i s t a n c e i n c a r r y i ng n ut c a r b o ni z a ti o n t e s t s .

REFERENCESBclinko. K . . C i a v a g l i a , L . A . and Nandi. B . N . "Energy f o r ind us t ry" , Ed.P . W . O'C alla ghan ; Pergamon Pre ss, (London); pp. 79-89 (19 78) .American Society f o r T e s t i n g a nd M a t e r i al s : P a r t 2 3 , D-189 (1975).Montgomery, D.S. and Nandi, R . N . F u e l s Re s e a rch Ce n t re D i v i s io n a l Re p o r t 73111; Department of Energy, Mines and Resour ces , O t t a w a , Canada (1'973).Elosrs, R . C . Ri t llminous Coal Research In c . , E lonroev i l le , Pennsy lvan ia ;['er s o n a 1 Commun i c11t i o n .

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NO ADDITIVE

60

x 5 5WP5 5 0

40

COAL -k 10% PITCH D

4 cmFIGURE 1: High Temperature Cokes Produced From Canister Te s t s

0 . 9 rB IN D IN G INDEX = C P e x p [ F F ]

/I3

BINDING I N D E X , PER C E N TFIGURE 2 : Rel ativ e Strength Indic es fo r Various Coal/Pitch Blends

143


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FLG U K E 3 : Optical Micrograph of Coke F I G U R E 4 : Op ti ca l Micrograph of CokeProauced from Coal With No Produced trom Coal + 5% Pi tchAdditive Showing Poor bonding D .Showing Dis co nt in uo us BondingBetween Fused Vitrinlte (FV) of Fused Mass (FPI) With Fusini-and Oxidizcd Vitrinite (OV) t i c S t r u c t u r e (F)

FIGURE 5 : Op tic a l Microgra ph of Coke FIGURE h :Produced from Coal+ 10 % P i t c hD Showing Excellent Bondingo f F u s i n i t i c S t r u c t u r e (F )by Fused Mass ( FM)

144

Op ti ca l Micrograph of CokeProduced From Loa1+167, Pi tchD Showing Development of Micro-cracks Within Fused Mass (FM)


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SYIVXETIC FUELS - PITFALLS AND PROMISE. Fre d Schu lma n. E ner gy Sy st em sTechnology Corp . , 927-15th S t . , N . W . , Washington, D. C. 2000.5T e c h n ic a l p r o c e s s im prov em en ts an d p o l i c y r e s t r a i n t s on O P E C ' s a b i l i t yt o i n cr e as e o i l p r i c e s a t w i l l a r e two e s s e n t i a l c om po ne nt s o f a v i a b l es y n t h e t ic f u e l s i n d u s t r y . One w it ho ut t h e o t h e r s p e l l s f r u s t r a t i o n andf a i l u r e . T he Ar ab o i l embargo o f 1 97 3- 74 a nd t h e s u b s e q u e n t f i v e - f o l di nc r ea s e i n pe tr ol eu m p r i c e s l e d t o m u l t i b i l l i o n d o l l a r pro gr am s t o de-v el op s y n t h e t i c f u e l s . E x p e c ta t i on s o f a g r e a t new s y n t h e t i c f u e l s i n -d u s t ry were u n f u l f i l l e d as p r i c e s 2nd c o s t s r o s e t ow ar d t h e i r e q u i v al e n t-v a l u s - t o -o i l . C os t d i f f e r e n t i a l s i n f a v o r o f i mp or te d o i l c o n t in u e t oi n c r h a s e y e a r b y y e a r d e s p i t e many c h e m ic a l a nd e n g i n e e r i n g i n n o v a t i o n s .F o r example , e s t ima ted c o s t s o f p r od u ci n g s h a l e o i l r o s e from $7 p e r b b l

i n 1973 t o $ 3O/bbl t o d a y . When t n e OPEC c a r t e l r a i s e d o i l p r i c e s a n o t h e rSk$ l a s t J un e , it became even more imp or t a n t t o encoura ge dom es t i c o i ls r o du c t io n an d t o d e ve l op e ne rg y a l t e r n a t i v e s . OPEC's new p r i ces w i l lf o r c e t h e b a s e p r i c e o f s y n th e t i c f u e l s t o r i s e t o $46-50 by 1983.i i s i n g f e e d st o c k c o s t s i m p e r i l t h e d om es ti c p e tr o c he m i c al i n d u s t r y an d? n da n g er c h e m i c a l e x p o r t s . T h i s p a p e r d e t a i l s some o f t h e s e p ro b le m s a n ds u g g e s t s a number o f ene rgy po l i cy a c t io ns a imed a t e s t a b l i s h m e n t o f t h ei o ne s ti c f u e l s i n d u s t r y o n a s o u n d b a s i s .

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Development of a Sim u la t ed C a t a ly s t Ag in g T ech n iq u eJ . F . K r i z a n d M . Ternan

Energy Research Labo l -a to r iesCanada Cen t re f o r Minera l and Energy Techno logy

Departmen t of Energy, Mines and Resou rces CanadaOttawa, Canada

K1A O G 1INTRODUCTTON

Under h y d r oc r a c k in g c o n d i t i o n s , h ea vy o i l s pr od uc e d e p o s i t s t h a taccumula te on t h e c a t a l y s t s u r f a c e . By p o i s on i n g and by h i n d e r i n g a c c e s s i b i l i t yof t h e a c t i v e s i t e s , t h e s e d e p o s i t s c a us e f o u l i n g of t h e c a t a l y s t . M a t e r ia ltha t i s so d e p o s i t e d i s e i t h e r o r i g i n a l l y p r e s e n t i n t h e f e ed , s uc h a s heavym e t a l s and m i n e r a l s , o r i s formed d u r i n g h y d ro c rac k in g . s u ch a s coke. Not a l ld e p o s i t s d e a c t i v a t e t h e s u r f a c e a t t h e same r a t e . I t was e s t ab l i s h ed b y r ep ea t edr e g e n e r a t i o n t h a t r a p i d f o u l i n g u nd e r t y p i c a l bi t um e n h y dr o c ra c k in g c o n d i t i o n si s cau sed p r im ar i l y b y co k e fo rm a t io n (1 ) . To o b t a in a l o n g e r - l a s t i n g f o r m u -l a t i o n , c a t a l y s t de ve l op m en t sh ou ld t h e r e f o r e f o c u s o n t y p e s t h a t r e s i s t cokef o r ma t i on . S uch a n e f f o r t would i n v o l v e a s y s t e m a t i c a p p ro a c h t o c a t a l y s tp ro d u c t i o n b as ed on i n f o r m a t i o n o b t a in e d i n a g i n g t e s t s .

To d e t e r m i n e t h e t r u e ag i ng c l i a r a c t e r i s l i c s , a c t u a l p r o c es s i n g cond-i t i o n s m u s t b e m a i n t a i n e d b e c a u s e th e y a f f e c t p r o d u c t f o r m a t i o n and t h e r e b ya l s o t h e p r o c e ss of d e a c t i v a t i o n . However, a s e r i o u s d i s a d v a n t a g e o f a g i n gt e s t s u nde r a c t u a l p r o c e s s i n g c o n d i t i o n s i s t h a t t h ey a r e s l o w and t h u s cons um ea g r e a t d e a l of t i m e and manpower. The t ime invo lved becomes c r i t i c a l i f ag i ngc h a r a c t e r i s t i c s a r e r e q u i r e d f o r a l a r g e number o f c a t a l y s t s . I t is t h e p u rp o s eof t h i s r e p o r t t o d e s c r i b e a t e c h ni q u e t h a t s i m u l a t e s c a t a l y s t a g in g and pro-v i d e s p r e l i m i n a r y i n f o r m a t i o n i n a much s h o r t e r t i me .

EXPERIMENTAL EQUIPMENT A N D MATERIALSA b en ch - s cal e f i x ed -b ed r e ac t i o n s y s tem was u s ed , i n which t h e

The equipment wasb i t um en m ix ed wi t h h y d ro g en f l owed u p t h ro u g h t h e c a t a l y s t b ed co n t i n o u s ly .Liquid and vapour were s e p a r a t e d in r e c e i v e r v e s s e l s .p r e vi o u s ly de s c r ib e d i n d e t a i l ( 2 ) b u t t h e f o l l o wi n g m o d i f i ca t i o n s were madet o ac co mm od at e t h e p a r t i c u l a r r e q u i r e m e n t s of t h e p r e s e n t s t u d y ( 3 ) :1. Bitumen was s t o r e d i n a heated hopper from which i t co u ld b e f ed t h ro u g ht a p s i n t o t w o 1000-mL b u r e t t e s i n a h e a te d p l a s t i c c a b i n e t . W it h a l i g h t

p o s it i o ne d b eh in d t h e c a b i n e t a n d , t h e i n s i d e o f t h e c a b i n e t h e at ed t oabou t 75OC, i t w a s p o s s i b l e t o mo ni to r t h e f e ed l e v e l i n t h e b u r e t t e s .A Mil ton Roy "Co nst amc tri c" p u m p , model numbcr 'TCP 4 3 - 4 3 TJ. was used t of e e d t h e b i tu m en t h r o u gh h e at e d l i n e s i n t o tlic r e a c t o r . A p res s u re g au g ew a s p l a c e d a t t h e pump o u t l e t t o m o n i t o r p r e s s u r e a t t h e pump h ea d .TO r e d u c e t h e r e a c t o r v ol um e, a s t a i n l e s s s t e e l i n s e r t w a s m ac hi ne d t o f i ti t , r e d u c i n g t h e i n s i d e d i a m e t e r t o 1 .2 7 cm fr om 2 . 5 4 cm bu t ma in ta in in gl e n gt h a t 30.5 c m .

2.

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The c a t a l y s t s e l e c t e d f o r c om pa ra ti v e r u n s was a commercial typeHarshaw 0603T with 3 w t Z COO and 12 w t % MOO s u p p or t e d on a l u m i n a . i n t h efo rm o f c y l i nd r i c a l 3.2-mm p e l l e t s . About 158 g of t h i s c a t a l y s t r e p re se n te da f u l l r e a c t o r l o a d b u t o nl y ab o ut 30 g c o u l d b e l o a de d w i t h t h e i n s e r t . T her a t e of a g i ng w a s e va lua te d us i ng Atha sba sc a b i tum en ob ta ine d from GreatCanadian O i l S a nds L imi te d a t F o r t McMurray, A lbe r t a . P r op e r t i e s of t he fe e d -s t o c k are l i s t e d i n T ab le 1.

TABLE IP r o p c r t ie s of htliah;isca Uitumcn

S p e c i f i c g r a v i t y 1.009 (15/15OC) Benzene in so lu bl es 0 .72 w t %Sulphur 4 . 4 8 w t X Carbon 86.36 w t %Ash 0.59 w t % Hydrogen 10.52 w t %Conradson Carbon Kesidue 13.3 w t Z Nitrogen 0.45 w t %1 5 . 5 w t Z l' it ch (525OC+) 51 .5 w t 9 .e n t a n e i n s o l u h l e s

OPERATING CONDITIONSThe co n d i t i o ns t h a t a f f e c t c a t a l y s t d e a c t i v a t i on i n a cont inuous

The hydr ocr a c k ing p r oc e ss c o ns i s t s of a number of complexf l o w s y st em a r e t e m p e r a t u r e , h yd ro ge n p r e s s u r e , h y dr og e n fl o w r a t e a nd l i q u i ds p a c e v e l o c i t y .r e a c ti o n s t e p s , i n i t i a l l y i n v o l vi n g v a r i o u s c o n s t i t u e n t s of b it umen. C a t a l y t i cp r o c e s s es on a c t i v e s u r f a c e s i t e s p a r t i c i p a t e i n some o f t h e r e a c t i o n steps.

Although i t w ou ld be d i f f i c u l t , b e ca u se o f c o m pl e xi t y o f t h e react-i o n s , t o p r e d i c t a c c u r a t e l y t h c Lmpact of c ha nges of a ny p r o c e s s in g c ond i t io n .some o v e r a l l e f f e c t s c a n be d e r i v e d f ro m t h e f u n da me nt al s o f r e a c t i o n k i n e t i c s .The r a t e of i n d i v i d u a l r e a c t i o n s t e p s v a r i e s w i t h t e m p e ra t u re a nd c o n c e n t r a t i o no f r e a c t a n t s .i n g t em p er a tu r e, w he re as h y dr o ge n at i o n r e a c t i o n s a c c e l e r a t e w i t h i n c r e a s i n ghydrogen pres sure . Coke [ormation depends on th e r a t e s of c ra ck in g and dehydro-ge na t ion , f o llowed by po lym e r iz a t ion . The r e f o r e c oke f o r m a t ion accelerates w i t hi n c r e a s i n g t e mp e ra t u re a nd d e c r e a s i n g h y dr og e n p r e s s u r e .

C ra ck in g r e a c t i o n s a r e e nd ot h er mi c a nd a c c e l e r a t e w i t h i n c r ea s -

The c o nd i t io ns f o r " s im ula te d a g ing" were chosen by performing as e r i e s o f s c r e e n i n g e x pe ri m en t s t o i n v e s t i g a t e t h e e f f e c t o f v a r i a t i o n s i ns p ac e v e l o c i t y a nd t e m p e r a t u re . T he e f f e c t o f h y dr og en p r e s s u r e o n c a t a l y s ta g i n g w a s s t u d i e d p r e v i o u s l y u s i n g a d i f f e r e n t e x p er i m en t a l s y st em ( 4 ) .t h e p r e s e n t s t u d y , t h e h yd r og en p r e s s u r e was m a in t ai n ed c o n s t a n t a t 13.9 MPaf o r a l l t e s t s , w h i c h i s w i t h i n t h e p r a c t i c a l r a n ge f o r h y d ro cr ac ki ng . A sat-i s f a c t o r y e f f e c t c o u l d n o t h a ve b ee n ac h i ev e d by v a r y i n g o n l y s p a c e v e l o c i t y ;a n i n c r e a s e i n t e m p e r at u r e w a s a l s o n e ce s sa r y t o r e d uc e ag i n g ti me s u f f i c i e n t l y .A f t e r some p re l i m in a r y e x p er i m en t a t io n , o p t i m y d e a c t i v a t i o n c o n d i t i o n s we refo un d t o p r e v a i l w i t h a s p a c e v e l o c i t y o f 5 h

I n

and a t a t e m pe r a tu r e o f 495OC.The following s e r i e s of t e s t s u nd er d i f f e r e n t o p e r a ti n g c o n d i ti o n s

a r e d oc umen te d i n t h e p r e s e n t r e p o r t :S e r i e s 1T r ue o r ba s e d e a c t i v a t i o n t a t ' s w er e m ea su re d a t 45OoC an d a t a l i q u i d v ol um et -r i c s pa ce v e lo c i t y o f 1 h- ba sed on th c r e a c t o r vo ume packed w i t h t h e c a t a l y s tp e l l e t s . The c o r r e s p o n d i n g f e ed r a t e was 152 mL h as no ins r t was p la c e d inth e r e a c t o r . The hydroge n f low r a t e w a s m a i n t a i n e d a t 35.6 cm's-l a t STP. T h i st e s t i s r e f e r r e d t o a s t r u e a g i n g a nd wa s r u n c o n t i n u o u s l y f o r 5 6 h o u r s , andt h e n p e r i o d i c a l l y i n f i v e - t o e i gh t -h o ur i n t e r v a l s , t o t a l l i n g a b ou t 200 hoursi n a l l . Analyses were performed on samples o f t h e l i q u i d p r o d u c t a c c u m u l a t e di n two to f i ve hour's of ope ra t i on .

-i

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S e r i e s 2H ig h s p a c e v e l o c i t y t e s t s were performed under t h e sa m e c ond i t ions a s f o r t r u ea g i n g - 1 3 . 9 m a , 450C. a nd w i t h o u t i n s e r t - e x c e p t f o r a d i f f e r e n t a r r a n g e m e n tof s pa ce v e l o c i t i e s . C a t a l y s t a g i n g w a s c a r r i e d o t i n two 12-hour pe r i od sdur in5 YPich spac e ve l oc i t y w . i b m a i n t a i n e d :i t 5 Ii95 c m s a t STP.was d e t r m 'ne d by c hang ing t he sp a c e ve lo c i ty t o 1 h- , t h e hydrogen f low to35.6 c>s-* a t STP f o r two hour s a nd a na lyz ing t hc l iq u i d sa mple tha t a c c umulate ddur ing the se two hour s .S c r i c s 3

-Y , a nd th e hydr oge n f low a tThe leve l of n c t i v i t y . i n i t i a l l y anf a f t e r e a c h 12-hour p e r i od

S i m u l a t e d d e a c t i v a t i o n r a t e s were measured a t high tempera ture and h i gh spacev e l o c i t l .of 5 h .was 181 mL.h . The hydroge n f low r a t e was m a in taine d a t a bou t 70 cm3s-' a t STP.The s e r i e s was r e f e r r e d t o a s s im ula te d a g i ng a nd was r un c on t in ous ly f o r 32hour s . The l i qu id p r oduct t h a t a c c umula te d du r ing e a c h hour o f op e r a t io n waswithd ra wn f o r a n a l ys i s .S e r i e s 4A l i n k bet we en s i m u l a t e d a g i n g an d t r u e a g i n g w a s s o u g h t b y a d d i t i o n a l t e s t s i nt h e f o l l o w i n g man ne r. T he s i m u l a t e d a g i n g c o n d i t i o n s were a p p l i e d f o r a p e r i o dof t i m e a nd wer e the n change d to m a tc h the t r ue a g ing c ond i t io ns f o r a pprox im a telytwo hours dur in g which two l i q u i d samples were ob ta in ed . The ru n was thent e r m i n a t e d , thc r e a c t o r rc - lo ; idcd w i t h a frcssli c a t a l y s t , a nd th e t e s t was rep-e a t e d f o r a d i f f e r e n t t i m e p e r i o d u n d er s i m ul a t e d a g i n g c o n d i t i o n s . T h re ed i f f e r e n t t ime p e r i o d s - 2, 4 and 6 h o u r s , r e s p e c t i v e l y - under s i m ula te d a g ingc o n d i t i o n s were examined.a g i p g t e s t w a s run a t 495OC w i t h t h e fe e d r a e of 760mL.h- , s p a c e v e l o c i t y of5h , and th e hydroge n f low r a t e a t 70 cm3s- ' a t ST1'.

T h i s t e s t was run a t 495OC and a l i qu id v olum etr i c spac e ve lo c i tyThy inse r t w a s p l ac ed i n t h e r e a c t o r and t h e c o r re s p o nd i n g f e d r a t e

N o i n s e r t was p la ce d i n t h c r c a f t o r an d t h e s i m u l at e d

S e v e r a l p r o c e s s i n g c o n d i t i o n s were a p p li e d d i f f e r e n t l y i n ea ch s e r i e sof t e s t s . Fo r i n s t a n c e , i n S e r i e s 2. t h e s p a ce v e l o c i t y was f i v e t imes g r e a t e rt h a n i n S e r i e s 1, w h er ea s t h e g a s f l o w r a t e was o n ly a b o u t t h r e e times g r e a t e r .I n S e r i e s 1, t h e g a s f 1o w: fe ed r a t i o w a s l ow er t h a n i n S e r i e s 3 , b u t h i g he rt ha n i n t h e si mu la te d a g i n g i n S e r i e s 4 . I n a d d i t i o n , t h c 1 e ng t h: d ia me t er r a t i owas i n c r e a s e d i n S e r i e s 3 by p l a c i n g t h e i n s e r t i n t h e r e a c t o r , t h er e by i n c r e a s-i ng t h e l i n e a r v e1 o ci t y: s pa ce v e l o c i t y r a t i o t h ro ug h t h e c a t a l y s t b ed . Theuse of t h e i n s e r t a n d v a r y i n g f l o w re g i me r e s u l t e d f ro m e x p e r i e n c e w i t h t h ee xpe r im e n tal sys te m a nd f a c i l i t a t e d smooth ope r a t ion . The c hange s made weren e ce s sa r y t o p r e ve n t t h e r e a c t o r p l u g g i n g a nd t o m a i n t a i n t e m p er a t u re p r o f i l e sw i t h i n t h e c a t a l y s t b e d .

Thc impact 01 i n cr c ;i s i ng t e m p e r a t u r e a nd s p a c e v c l o c i t y i s d i s c u s s e di n t h e n ex t s e c t i o n of t h i s r e p o r t . V a r i a t i o n s i n hy dr oge n fl o w a r e n o t con-s i d e r e d s i g n i f i c a n t f o r t h e pu r po s c o f t h i s i n v e s t i g a t i o n , b ec au se a n e x ce s sof hydrogen was used i n a l l exp or im ents and because hydrogen f lo w seemed t oe x h i b i t o n l y a small e f f e c t o n p r o d u c t f o r m a t i o n ( 5 ) .

RESULTS A N D D I S C U S S I O NTrue Aging

The d e a c t i v a t i o n p a t t e r n is shown i n Fig .1 i n terms of a n i n c r e a s e i nt h e s p e c i f i c g r a v i t y of the l i q u i d p r od u c t an d a n i n c r e a s e i n i t s s u l p h u rc o n t e n t . I t c an b e p r e d i c t e d by e x t r a p o l a t i o n t h a t f u r t h e r d e a c t i v a t i o n would

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be recorded beyond 200 hou rs of op er a t io n . However , i t c a n b e se en t h a t d e -a c t i v a t i o n i s more r a p i d i n t h e e a r l y s t a g e s of t h e t e s t t ha n i n t h e l a t e rs t a g e s . S i nc e d e a c t i v a t i o n d e c e l e r a t e s w i t h t i m e . t h e c u r v e s i n F i g . 3 maye v e n t u a l l y l e v e l o f f , i n d i c a t i n g a c o n s t a n t a c t i v i t y . The d e c e l e r a t i n g de -a c t i v a t i o n i s i n a gr ee me nt w i t h r e s u l t s o f a pr e v iou s s tudy which a l s o showedt h a t t h i s l e ve l in g -o f f i s r e l a t i v e l y mo re pro no un ce d a nd t a k e s p l a c e e a r l i e rw i t h i n c r e a s i n g h yd ro ge n p r e s s u r e ( 4 ) . Whether a s t a t e o f c o n s t a n t a c t i v i t yi n f a c t e x i s t s i s not known a s t h e p a t t e r n s i n F i g. 1 c a nn o t be e x t r a p o l a t e dw i t h a ny p r e c i s i o n . F ur th er mo re . t e s t s c a r r i e d o u t c o n t i n u o u s l y f o r l o n g e rthan 200 h o u r s of o p e r a t i o n a r e n e ce s sa r y t o d et e rm i ne d e a c t i v a t i o n p a t t e r n sth a t a r e una f f e c t e d by s t a r t - up a nd shu t- down p r oc e du r e s . The se long-t e r mt e s t s a r e t o be performed on a s p e c i a l t e s t i n g s y st em p r e s e n t l y u n d er con -s t r u c t i o n .High Space Veloc i ty

The r e s u l t s of t h e hi g h sp a ce v e l o c i t y t e s t s i n cl u de d a n a l y t i c a ld a t a o n l i q u i d p r o d u c t s am pl e s o b t a i ne d f o r b o th h i g h an d b a s e s p ac e v e l o c i t i e sof t h i s s e r i e s . The r e s u l t s f o r t h e b a se s p ac e v e l o c i t i e s s e rv e d a s a measureof d e a c t i v a t i o n a f t c r c o mp le ti ng a p e r i o d w i t l i h igh spa c e ve lo c i ty . The de-a c t i v a t i o n i s i n d i c a t e d i n t h e le f t- h an d s i d e o f F i g .1 ,

A f i v e - fo l d i n c r e a s e i n f ee d r a t e had an i n s i g n i f i c a n t e f f e c t o n t h er a t e of d e a c t i v a t i o n . One c ou ld r a t i o n a l i z e t h i s f i n d i n g by as su mi ng t h a tlower c onve r s ions c a use d by r educ ed r e s ide nc e t i m e would compensa te f o r t h eg r e a t e r f e ed r a t e i n r e l a t i o n t o c ok e f o r m at i o n . However. a m o r e d e t a i l e da n a l y s i s would r e v e a l t h a t t h e r e l a t i o n s h i p be tw een t h e s p a ce v e l o c i t y an d t h er a t e of d ea c t iv a t io n may be more complex, mainly because of t h e mul t icomponents t r u c t u r e o f t h e r e a c t i o n s ys te m. The c o n c e n t r a t i o n of r e a c t i o n c o n s t i t u e n t sd ep en ds o n t h e x a t e s o f t h e i r fo rm at i on and d e p l e t i o n . T hu s t h e t o t a l y i e l d o fa component may no t he a monotonic fu nc ti on of th e res id en ce t i m e . I f somec o k e p r e c u r s o r s r e a c t f a s t e r th an o t h e r s , t he n t h e i r p a r t i c i p a t i o n i n t o t a l cokcf o r ma t i on d e p en d s o n t h e s p a c e v e l o c i t y , a change i n which may co nse quen t ly ber e f l e c t e d i n b ot h t h e q u a n t i t y an d t h e q u a l i t y of t h e c ok e d e p o s i t s . I n a d d i t i o nto c he m ic a l phenomena, m e c ha n ic a l r e g e ne r a t io n may t a ke p l a c e whe re by pa r t i c l e sof coke a re d e t a c h e d f ro m t h e s u r f a c e by a b r a s i o n or by d i s s o l u t i o n o f t h e b in d-ing c a r bonac e ous m a te r i a l . S hould n s i m i l a r p r o c e s s t a k e p l a c e w h i l e b it um eni s used, i t would b e e nh a nc ed by i n c r e a s i n g t h e s p a c e v e l o c i t y .

The h ig h sp ac e v e l o c i t y s e r i e s i n d i c a t e d t h a t t h e d e s i r e d e f f e c tc o ul d n o t b e e s t a b l i s h e d b y ch an gi ng t h e s p a c e v e l o c i t y a t b a s e t e m p e r a t u r e .To a c c e l e r a t e a g in g s u b s t a n t i a l l y , t h e c a t a l y s t f o u l i n g was s im u la t ed a t ah i g h e r r e a c t i o n t e m p e r a t u r e . The te rm s i m u l a t e d a g i n g i s use d t o e mpha siz et h e s e v e r e c on s eq u en c es o f t h e ch a ng e i n t e m p e r a t u r e .Simulated Aging

The r e s u l t s o f t h e s i mu l a te d a g i n g t e s t s a r e shown i n F i g . 2 . Thea c t i v i t y d ro pp ed r a pi d l y i n t h e f i r s t p e ri od o f t h e r un , l e v e l e d o f f , andremained approximate ly cons tant beyond 1 5 h o u r s o f o p e r a t i o n .

The pe rf o rm a nc e u n de r s i m u l a t e d a g i n g r e f l e c t e d t h e e f f e c t o f b o t hhigh tempera ture and h igh space v c l o c i t y . The performance seemed t o he mores e n s i t i v e t o t em pe ra tu re , p a r t i c u l a r l y w i t l i r e s p e c t to t he p i t c h f r a c t i o n o ft h e b it um en . The i n i t i a l h i gh p i t c h c o n v e rs i o n o b se rv e d c o u l d r e s u l t f r omm o l ec u l ar w e ig h t r e d u c t i o n o r gr ow t h. M o l ec u l ar g ro w th w ou ld r e s u l t i np r e c i p i t a t i o n of c ok e , m os t o f w hi ch wo uld b e r e t a i n e d o n t h e c a t a l y s t s u r f a c ea nd r e a c to r w al l s . The moleculor weight rcd uc t i on by c rac ki ng would gen era t ecompounds having a l ow er b o i l i n g p o i n t t h a n t h o s e c o nt a i n ed i n t h e p i t c h . I t

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i s a p p a r e n t t h a t , w h e r e a s b o t h o f t hc l a t t e r p r oc e sse s Iiavc t a ken p la c e s imul -t a ne ous l y , t h e gr owth r a t e was much sm a l l e r be c a use t h e amount of cok e formeda c c o u n t s f o r on ly a f r a c t i on o f th e p i t c h c onve r t e d . However, t h e h igh te mper -a t u r e o f s i m u l a t e d a g i n g co mp ar ed w i t h t r u e a g i n g s h i f t e d t h e b a l a n c e t o wa rd sc ok e fo rm at io n a s r e f l e c t e d i n r a p i d c a t a l y s t d e a c t i v a t i o n .

L e s s e x t e n s i v e h y d r og e n a t i o n u nd er s i m u l a t e d a g i n g c o n d i t i o n s ,ind ic a te d by a l o w H: C r a t i o , was pr esum ab ly due to a h igh a r om a t i c c a r bonc o n t e n t . An a n a l y s i s by F our i e r Tr a ns f or m C-13 N . M . R . i n d i c a te d t h a t t h eu n s a t u r a t e d c a r b o n r e p r e s e n t e d a b o u t 30% of t h e t o t a l ca rbo n i n t h e i n i t i a lp r oduc t of s im ula te d a g ing com a r e d wi th a bou t 20% of th a t o f t r ue a g ing . Thefol l owin g reas ons may be cons '1r c d to a c c ou n t f o r c ha ng es i n t h e a r o m a ti cc a r bo n c o n t e n t . More e x t e n s i v e s p l i t t i n g of s i d e c h a i n s from a r o ma t i c r l n g scaused by th e h ig her temp era t ure could liave y ie ld ed more g as i n t h e p r o d u c t .A p a rt from h y d ro c r ac k i n g r e a c t i o n s , t h e h i gh e r t e m pe r a tu r e a l s o s h i f t s t h en a ph t h en e s- a ro m at i cs e q u i l i b r i a t o wa r ds f o r m a t i o n o f a r o m a t i c s (6 ) . In add-i t i o n t o t h e t em p e ra t u re e f f e c t s , t h e h ig h s p a ce v e l o c i t y o f s i m u l a te d a gi ngmay ha ve h inde r e d t h e e x t e n t of hydrogcna t ion hccausc of t h e s h o r t e r c o nt a c tt ime .Link between Si mul ate d and Tru e Aging

S i n c e t h e r a t e of d e a c t i v a t i o n u n de r s i mu l a t ed a g i n g c o nd i t i o n sc o u ld no t e a s i l y b e r e l a t e d t o t h e r a t e of d e a c t i v a t i o n u nd er t r u e ag i n gc ond i t io ns , a s e r i e s o f e xpe r im e n t s was pe rf o rm e d i n which a l i n k was sough tbe twe e n s im ula te d a nd t r u e a g in g . The pu r pose o f th e s e e xpe rim e n t s w a s t om ea s ur e t h e l e v e l of a c t i v i t y u nd er t r u e a gi ng c on d i t i o n s a f t e r t h e c a t a l y s thad been su bje c te d t o s i m u la t c d a g i ng c o n d i t i o n s f o r a c c r t a i n p e ri o d oft ime, and then t o g r a p h i c a l l y es t i m a te t h e t i m e i n wh ic h t h e c a t a l y s t wouldd e t e r i o r a t e enough t o r e a c h t h i s l e v e l of a c t i v i t y w h i l e be in g s u bj e c t e d t ot r u e a gi ng c o n d i t i o n s .

The a c t i v i t y l e v e l s de te rmi ne d f o r t h r e e d i f f e r e n t t i m e pe r iods unde rs i m u l a t e d a g i n g a r e m ar ke d o n t h e ri g h t- h an d s i d e of t h e c u r v e s i n F i g . 1 . Bya pp ly in g t h e s e r e s u l t s i t was e s t i m a t e d t h a t 2 h o u r s o f o p e r a t i o n u nd e r s i m u l -a t e d a g ing c ond i t io ns would c or r e spond t o a bou t 50-70 hour s unde r t r u e a g ing .a n d s i m i l a r l y , 4 hour s t o 100-150 ho ur s , and 6 h o u r s t o 150-200 ho ur s. Hence,a s s u m i n g t h a t s i m u l a t e d a g i n g i s a p p r o x i m a t e l y 30 t i me s f a s t e r t h an t r u e a gi n g,o ne c ou ld e x t r a p o l a t e t h c p a t t c r n of t r u e a g i n g and s p c c u l a t e t h a t i t wouldl e v e l o f f i n a b ou t 400 h o u r s of o p e r a t i o n .

E s t i m a t i n g t h e l i n k h et we cn t r u e and s i m u l a t e d aging i n F ig .1 i s anapproximat ion onl y . However , i t i s a p p a r e n t t h a t by u s i n g s i m u l a t e d a g i n gc o n di t i o ns , t h e d e a c t i v a t i o n was a c c e l e r a t e d s u f f i c i e n t l y t o p ro ce ed s u b s ta n t -i a l l y i n a v er y s h o r t t i m e . I t i s e xpe cte d t h a t by a pp ly ing t h i s method t o anumber of c a t a l y s t s , p r e l i m i n a r y i n f o r m a t i o n c a n b e o b t a i n e d by c om pa ri ng t h e i rd e a c t i v a t i o n p a t t e r n s s uc h a s t h e one shown i n Fig . 2 . This info rmat ion wouldt he n be a v a i l a b l e e i t h e r i n a d d i t i o n t o t h e t r u e a g i ng d a t a , or f o r u s e w i thc a t a l y s t s on w hi ch t r u e a g i n g t e s t s a r e n o t w a r r a n t ed .

ACKNOWLEDGEMENTST he a u t h o r s w ic h t o e xp r es s t h e i r s i n c e r e ap p r e c ia t i o n t o R . W . Taylor

f o r m o di f yi n g t h e e x p e r i m e n t a l s y s te m a nd t o L. G a l b r a i t h f o r t e c h n i c a la s s i s t a n c e .

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REFERENCES1. McColgan, E . C . a n d P a r so n s , D . I . "The hydroc rack ing of re s idua l o i l s and

t a r s . P a r t 6: C a t a l y s t d e a c t i v a t i o n by c o ke a n d m e t a l s d e p o s i t i o n " ;Department of Energy, Mincs and Reso urces . Mines Branch ( s i n c e renamedCanada Cen tr e f o r Min er al and Energy Tcchnology (CANMET))Research Rep ortR273; 1974.

2. O'Grady, M.A. a n d P a r so n s , B . I . "The hydro genat i on of Al be r t a bi tumenover co ba l t molybda te ca ta ly s t " ; Depar tment o f Energy, >!ines and Resources ,Mines Branch, Re se ar ch Rep ort R194; 1967.

3 . Kr iz , J.F. and Ternan, M . "Development o f a s i mu l at e d c a t a l y s t a g in gte ch ni qu e" ; Ene rgy , Mines and Re so ur ce s, C anada, CANMET Re po rt 78-24; 197 8.

4. Ranganathan, R . , Logie , R.B. and Deni s , J.M. "C a t a l y t i c hydroc rack ing ofAthabasca b i tumen i n a f l u i d i z e d b ed r e a c t o r - e f f e c t o f p r e ss u r e o n c a t a -l y s t dec ay" ; Energy, Mines and Re so ut ce s, Canada, CANMET Re po rt 77-40;1 9 7 6 .

5. M e r r i l l , W.H., Logic , R . H . and Dcnis , J . M . " T h e e f f e c t of h y d r o g e n r e c y c l er a t e on t h e n o n - c a t a l y t i c h y d ro c r ac k i ng o f G.C.O.S. se p a r a t e d b i t u m e n " ;Department of Energy, Mines and Reso urces , Mines Branch; D iv is io na l Repo rtF R C 72/115-PPE; 1972.

6. Gul ly , A . J . a n d B a l l a r d , W.P. " Hy d ro g en a ti on of c a t a l y t i c c r a c k i n g c h a r g est oc ks "; Adv P e t Chcm Rc fi n (Ncw Y or k, I n t e r sc i e n c e . P u b l i s h e r s ) 7:2 40- 28 2;1963.

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I0s!-5

Fig . 1

............. GHOURSt I I O U R S . i-----2HOURS. . . . .. .. .- * * *1 510 . .:...*09-,. I- .--0 a 0 bo ti o 100 1x1 w o ~ G O ira 200 1I1IOUI~S

Spe c i f i c g r av i t y (15 /lSC) and su lphu r con ten t (wt X )i n t h e l i q u i d p ro du ct v e r s u s t i m e on stream (h ) du r ingt r u e a g i n g .A c t i v i t y l e v e l s o n r ig ht -h an d s i d e r e l a t e t o d i f f e r e n tt i m e p e r i o d s u n d er s i m u la t e d a g i n g .

0 i n d i c a t e s h i gh s p ac e v e l o c i t y e xp er im en ts .

-........................i. . . . . . . . . . . . . . . . .30t IOUf(S 2o10

Fig .2 Sp ec i f i c g r a v i ty (15 /lSoC) and su lp hur con ten t ( u t I)i n t h e l i q u i d p ro du ct v e r su s t ime on stream (h) d u r i n gs imula ted aging .

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REMOVAL O F ORGANIC SULFUR FROM C O A L : TH E USE O F LIQUID SULFUR DIOXIDEDuane F. Burow and Boris M. Glavincevski

Department of Chemistry, University of Toledo, Toledo, Ohio 43606ABSTRACT

The ut i l i t y of l iquid SO, for the removal of organic sulfur fromsevera l Eastern bituminous coa ls has been exp lored. Reactions were ca rr ie do u t in sealed f ri tt ed glass tubes a t elevated temperatures; a ft er subse-quent washing, th e coal was analyzed fo r sul fu r con ten t. Approximately40% of th e organic s u l fur could be removed in these simple explo ratoryexperiments.portion of the coal was ext rac ted . The ex tr ac t from sel ect ed coal s wascharacterized by thin-layer chromatography, by n m r ('H and 1 3 C ) and infraredspectroscopy, and by fi eld- io niza ti on mass spectrometry. For comparison,extractions with phenol a n d p c r e s o l , under simi lar conditions, were als oexamined. The re su lt s of these preliminary inves tiga tion s warrant fu rt he rresearch to es tab l is h optimum conditions fo r the removal o f s ul fu r compoundsfrom coal by treatment with l iquid SO2 and to f a c i l i t a t e removal of residualSO2 from the coal.

In add it io n, comminution of most of the coals occurred a n d a

I NTRO DUCT1ONSol vent ext rac tion has been extensively used f o r compositionalcharacterization of coals. 1'2 Several ex i st ing coal ref in ing p r o c e s s e ~ ~ - ~use solvent treatment, along with pressurized hydrogen t o f a c i l i t a t e somedegree of desulfurization.used t o remove organic su l fur compounds from petroleum on a commercialscale.6 The ability o f l iquid SO2 t o disintegrate various coals has beenexploited to produce low-sulfur coal powders via rel eas e of p yr it e. 7Utilization of liquid SO2 treatment of coal for th e removal of organicsu lf ur , however, has not been inv est iga ted . In th i s paper we report

the results of a se t of preliminary experiments in which the effectivenessof liquid SO2 for removal of organic sulfur from bituminous coals PSOC 194,267, 2 7 0 , a n d 319 was investigated.

Treatment w i t h 1 i q u i d SO, has been successfully

EXPERIMENTALProcedures for the manipulation and preparation of the sulfur dioxide(Matheson, anhydrous) have been described previously.were obtained from the Coal Research Sect ion, Pennsylvania St ate University.All ot he r mater ial s were of commercial or ig in a n d used as received.

Coal samples

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Reactions were ca rr ied out i n boros i l ic ate glass tubes f i t t e dwith a mdium-poros ity f r i t t e d glass f i l t e r to provide two chambers o f ca.20 mL capacity each. lass tubing of-di f fe re nt s izes : one end permitted introd uc t ion o f lump f ~ .cm) coaland th e other end fa c i l i ta te d easy se alin g under vacuum. F or reac tionsa t eleva ted temperatures, these tubes were placed i n a P arr model 4641autoclave reactor.sample (G . 5 g) s ea led on one end, and thoroughly evacuated.d i s t i l l a t i o n o f s u l f u r dio xide (s.mL) i n to the tube a t -78"C, thereac tion tube was cooled to -196C and sealed a t the oth e r end. Uponwarming to room temperature, the tube, alo ng w i th othe rs , was pl ac ed i nthe autoclave and th e autoc lave was evacuated. The autocla ve was thencharged with g. 00 mL o f l i q u i d SO, to provide backing pressure f o r therea ctio n tubes a t el eva ted temperatures, closed, and heated a tz. "C/minto the reaction temperature.f o r 60 min, the autoc lave was cooled, depressurized, and opened.rea ctio n tube was then in ve rte d i n a c o ld bath a t -78C to separate thel i q u i d SO, from the coal by f i l te ra t io n v ia the internal frit. The red toorange co lored l i q u i d SO, s o luti on was frozen, the tube was opened, thecoal was tran s ferre d to another container, and a l l vo la t i l e materials wereallowed to evaporate o ver a two hour period. The viscous, o i l y ex trac tremaining af te r evaporation o f the l i q u i d SO, was re taine d fo r subsequentanalys is .Buchner funnel wi th sequential a l iqu ots o f di s t i l l e d water, acetone, water,3.8 M n i tr i c acid, water, and acetone u n t i l no yello w c o lo r was observed i neach wash liquid.I n separate washing experiments w i th the raw coa ls, no ye ll ow c o lo r wasobserved i n the wash l iq ui ds ; subsequent su lf ur analyses o f the coalind ic ated th a t only ino rga nic s u l fu r was removed from the raw coal by thi swash procedure.F or comparison o f the re s ults o f these c oa l/ l iq ui d SO2 experiments,two othe r types o f experiments were al s o run. A uthentic samples o f ir o npyr i te were t reated wi th l i q u i d SO2 and l i qu id S0,/H20 mixture s a t 100Cus ing procedures analogous to those des cribed above; no apparent reactionoccurred.and p-cresol i n s e a l x tubes a t 181" and 2OOoC, respe ct ively.subs equently washed i n a Buchner funnel with d i s t i l l e d water and acetone,d ri e d a t l l O C , and analyzed for sulfur.

A l l s ul fu r analyses, a t le as t in t r ip l i c a te , were accompl ished with a, F isher mde l 470 s ul fu r analyser.on a Varian model MAT CH5 spectrometer w i th sample temperatures from 120"-280C. The 'H and 13C nmr spectra w e r e recorde d on a J EOL FX9OQ F ou riertrans form spectrometer f i t t e d wi th a broadband probe and deuterium loc k.Samples were i n CDCl , s ol utio n wi th in ter na l TMS reference.of the extra ct ( th i n f i l m on NaCl plates) were recorded on a P erkin E l m e rmodel 621 spectrometer. T hin- la ye r chromatography o f th e e x tr a c t wasc ar ri e d out with the nmr sample so lutions us ing s i l i c a ge l (S i -30) p la tes .E lution was accomplished wi th 10% acetone/hexane, 30% acetone/hexane, and

absolute ethanol; either I, vapor o r phosphomolybdic a c id (5% w/v i n ethanol)was used t o develop th e pl ate s .

The chambers w e r e terminated wi th

I n a typ ic a l experiment, the re ac tion tube was charged wi th a coalA f t e r

A ft e r maintenance o f the rea ctio n temperatureEach

The tre a te d coal was washed f o r ana ly tic al purposes i n aThe coal was then dr ie d a t 110C and analyzed f o r su lf ur .

Samples (ca. 4 9) o f PSOC 267 were tre a te d w i th 10 mL o f phenolThe coal was

F ie ld - io ni z ati on mass spectra were obtained

In f rar ed spectra

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RESULTS AND D I S C U S S I O NP recombustion de s ul fu ri z ati on o f coal has been a top ic o f immensein te re s t and importancelO*ll s ince it of fe rs an a l te rnat ive to ins ta l la t ionand ope ration o f expensive post-combustion scrubbers f o r conventionalcombustion systems. A lthough a vari ety o f processes are available fo rprecombustion removal o f ino rga nic s u l f u r compounds, pr ac tic a l proceduresf o r removal o f co val en tly bound organic s u l fu r are r e l a ti ve l y uncommon.Thus, ap pl ic ati on o f novel chemical approaches t o the problem would appearto be appropr ia te . E ar ly reports12 o f the a b i l i t y o f l i qu id SO2 t odis integrate a var iety o f coa ls and t o extra ct a port ion o f the coal a longwith our previous experience with this solvent suggested investigation o fth e u t i l i t y o f l i q u i d S O2 as a means o f removing organic sulfur from coal.If uccess ful, such a procedure would u ti l i z e a po ll uta nt to remove thesource o f that po l lu tant .L iqu id su l fur d iox ide i s recognized as an exc el le nt so lvent f o raromatic, he teroc ycl ic , and al ky l s ul fi de s 8 which can be deri ved fromcoa1.1,2y13 As a l iqu id , S O2 i s no t ea s i ly o xidized o r reduced and theadducts responsible f o r i t s s olvent properties are both thermally andhy dro lyt i ca l l y labi le ;8 thus any contamination o f the coal by residualsu lfur dioxide should be readi ly el iminated. Although other intera ct ion sand reactions w i l l be considered i n futur e repo rts, only reac tions basedon the mi ld Lewis ac id c haracter is t ics o f l iq u id SO2 are o f importancehere. Thus, the rea ctio n o f sig nifi ca nc e i s summarized by Eq.1:

I I-s :.. f so2 -+ -?:SO2 (1)Products from this react ion are usually highly colored and highly solublei n l i q u i d SO,.8 P hysical d is integrat ion o f the coal by l i q u i d SO, probablyvia s im il a r donor-acceptor reac tions wi th aromatic, amine, and oxygenco ntainin g func tiona l groups, would serve to promote the rea ctio n i n Eq.1.I t should be emphasized th a t frequently, the chemical pro perties o f l i q u i dSO2 can be si g ni f i c a ntl y a lter ed by the presence o f cosolvents;8 often,undesirable side reac tions occur i n such mixed media.The cha racter is t ics o f the bituminous coals ut i l i z e d i n theseprel iminary invest igat ions are given i n Table I; ur sulfur analyses aregiven i n parentheses.s ign i f i can t amounts o f o rganic s u l f u r bu t l i t t l e p y r i t i c s u l f u r whichmight confuse in terp re tat io n o f prel iminary results. Our analyses o fPSOC 270 reveal th a t, althou gh the lumps i n our sample had the compositionindicated i n Table I, he f ine s i n our sample had a s ul fu r content o f-a. 6% wi th the additional s ul fu r being p yr i t i c . A l l results reported hereconcern the lump coal o f PSOC 270. F or comparison, P S O C 194 which containsboth pyr i t ic and organic sul fur and PSOC 319 which contains only pyrit ics ul fu r were als o examined. Use o f the fr i tt e d glass reac tion tubesfaci l i tated observat ion of react ions, iso lat ion of the extracted mater ia l ,and ra pi d examination o f several coals and reaction conditions.The res ul ts a re summarized i n Table 11. A t room temperature,l i q u i d S O2 re ad il y wets each o f the coals and begins t o develop a yel lo wc o lo r upon co ntac t. The ye ll ow c o lo r becomes more intens e upon stand ingand changes to intense orange o r red-orange a f te r heating.in di ca tes the d is s o lu tio n o f donor-acceptor compounds formed betweenthe s olvent and coal con stituents; the inc reas ing i nt e n s ity accompanies

PSOC 267 and 270 were chosen since they contain

The color

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an increasing concentra tion of these adducts. Disint egra tion of coallumps was observed f o r PSOC 267, 270, and 319; the extent of disinte-gration inc reases progressively in the order l i s t ed . Although lumps ofPSOC 194 were not disintegrated, close examination revealed apprec iableswelling a n d expansion along fissures.only mechanical agi ta ti on used d u r i n g these experiments was a mild shakingof the tubes t o i ni t ia ll y mix the materials.appear t o be an obvious pattern which links maceral content t o degree ofdisintegration .Inspection of Table I1 reveals that significant amounts of SO, areretained o n th e coal (Exp. 1 ) . Effective removal of this residual SO2 i sessent ial .solutions were less effective t h a n the wash solution used in Exp. 2 . Whenused alone, organ ic solv ent s a re more ef fe ct iv e than mineral acid o r base(compare Exp. 2 and 3 with Exp. 4 , 5 , and 6 ) . The u t i l i t y of washing withthe organic liquids for removal of the yellow SO2 adducts increases in theorder: hexane, benzenesCClpethano1, and acetone. A sequence of washesu s i n g acetone, water, a n d HN03 (Exp. 7) effectively removes the residualSO, in most ca ses. Since the wash sequence was carr ied out during afilteration operation contact time with the HNO, was insufficient toappreciably modify the coal material itself; separate wash experimentsusing the acetone, water, HN 03 sequence with the raw coal (PSOC 267 a n d 270)i ts e lf indicated th a t no appreciable ma s s change occurred a n d t h a t noyellow materials were obtained under these wash condit ions . Where pyri tei s n o t present, th e su lf ur content of the coal a f t e r t h is wash sequencerepresents the organic su lf ur remaining in the coal a f t e r th e liqu id SO2treatment. For PSOC 267 and 270, G . 37%and 25%, respectively, of theorganic su lfur can be removed by simple trea tment of th e lump coal withl iquid Sop. Grinding the lump coal P S O C 270 (-60 mesh) improves thepercentage organic sulfur removal t o g. 8%. Present res ul ts with coalscontaining pyrite are l es s ea si ly i nterp reted since t he wash sequenceprobably does n o t completely remove the py ri te . Furthermore, in separateexperiments with authentic p yr it e samples, i t was demonstrated t h a t neitherl iquid SO2 nor l iquid S02/H,0 mixtures react with pyrite.where virtually all th e sul fu r i s py ri tic , the measured value of 1.6%su l fur a f t e r SO, treatment probably represents pyri te which i s no t removedin the wash sequence. For PSOC 194, the measured value of 2 . 1% su l fu r a f t e rl iquid SO2 treatment m o r e t h a n likely represents both unreacted organicand pyrit ic sulfur.the coal probably limited extraction o f the organic su lf ur by the SO,Extraction o f powdered PSOC 267 with phenol and p-cresol re su lt edin 52% and 66%, respec tively , remval o f organic su lf ur compared to 37%by liquid SO, The results of the extractions with phenol and pcresolare similar to those reported elsewhere for other coals.Although these results with liquid SO, a r e n o t a s impressiveas those with phenol and e-c re sol , i t has been demonstrated t h a t organicSu lf ur can be removed by ex tr ac ti on with l iquid SO,. I t is also importantto note that optimum conditions for liquid SO2 extraction a n d for residualSo2 removal have as yet t o be established. Furthermore, these preliminaryre su lt s when compared with oth er worker's r e s ul t s l 0 f o r a varie ty of organicsol vents, are su ff ic ie nt ly encouraging t o indicate that treatment withl iquid S o2 should be invest igated further. Experiments t o define conditions

I t should be real ized t h a t theA t this stage, there does n o t

Mild heating (110C) and washing with water or aqueous detergent

For PSOC 319,

With PSOC 194, the fai lure of l iquid SO, to disintegrate

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more ca re fu l l y and to inves t igate the use o f appropriate reagents tha tw i l l enhance the removal o f s u l f u r compounds f r o m coal by l iquid SO2are underway.comprises 5-10% o f the or ig in a l coal.i n chloroform, acetone, and con centrated HC1; h is mater ia l i s o nl y p a r t i a l l yso luble i n benzene and i s inso luble i n hexane.pa rt ic ul ate matter, observed to be i n suspension i n the chloroform andacetone so lutions appears to resemble high m l e c u l a r weight materialobtained by Larsen and Choudhury13 during t h e i r i nve s tiga tion o f theeffectiveness o f coal depolymerization reactions . Although it i s l i k e l yth a t l i q u i d SOn under these conditions merely extracts lower molecularweight material a1 ready i n the coal, some small degree o f depolymeriz ationcould a1so be occurring.was ca rr ie d out us ing a chloroform so lut io n f o r depos ition and elu ted wi thP rogre ss ivel y more pol ar solven ts; long-wavelength UV i l lu min at i on was usedt o observe fluorescence i n the samples. Although no d i s ti n c t bands weredeveloped upon e lut ion, three d ef in i te f ract ions that d i f f e r by po la r i tyo f cons tituents were apparent on the pla tes. S everal conclus ions can bedrawn from these TLC experiments. The complete sample contains e a s i l yoxidizable funct ions. A l l alk yl funct ions are attached t o aromaticres idues. The les s conjugated (blue fluorescent) f rac t ion i s less po la rthan the more conjugated (orange fluorescent) fraction. A very polarfrac t ion, no t transported by any eluent used, i s even m r e hi gh ly conjugated(red f luorescent).structures14 known to e x i s t i n coals as wel l as with the spectroscopicmeasurements t o be de sc ribe d ne xt.PSOC 267 i s i l l u s t r a t e d i n F i g. 1; the corresponding spectrum o f th e extra ctf r o m P SOC 270 i s s i mi la r i n several features. The molecular weightdi s tr ib ut i on i n these spectra are not as broad nor i s the average molecularweigh t as hi gh as might have been expected.14 The presence o f very f i n e l ydivid ed p a rti c ul a te matter, which presumably has high er molecular weightcomponents that are not volatilized under the measurement conditions, couldbe responsible f o r such observations. The sp ectra contain s tr i k i n g patternsi n which the mass di ffe re nce among major components i s 14 amu. Thesepatterns suggest the presence o f a va r ie t y o f CH2 containing structures.It s tempting to ass ign another p atter n near m/e = 184 t o dibenzothiophenesince it s trong ly resembles th a t obtai ned wi th an authe ntic dibenzothiophenesample. The la ck o f hi gh re s o lu tio n mass s pe c tra l data, however, makes suchan assignment pure sp ec ula tion a t th i s stage.The inf r are d spectrum o f the l i q u i d SO2 e x tr a c t o f P S O C 267 (neat,th i n f i l m) i s shown i n F ig. 2. I t i s apparent that the e xtrac t conta ins0-H, N-H, aromatic and aliphatic C-H groups, a var ie ty o f s ub s tituted aromaticstructures, and probably ethers. There i s no evidence o f e ith e r residua lso2 o r o f o rgan ic s t ructures conta in ing SO2 substitution; no procedures otherthan evaporation o f the l i q u i d SOn under ambient conditions were used toprocess this extract.

The material obtained by evaporation o f the SO2 ex t rac t ion l i qu idF b s t o f t h i s o i l y e x t r a c t d is s o lve sVery f ine ly div ided

T hin-la yer chromatography o f the l i q u i d SOn ex trac t f rom P S O C 267

These observations are cons is tent wi th the types o fThe f i e l d ioniz at ion mass spectrum o f the l i q u i d SO n extract f rom

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P roton and l 3 C (proton nois e decoupled) nmr spectra o f the l i q u i dQua l i ta t ive ly , the pro tonO2 extract o f PSOC 267 are shown i n F ig. 3.spectrum resembles th a t o f CS2 extracts o f other bituminous coals asrepo rted by R etcofsky and F riede l ;15 ou r assignments follow those o fthese workers.those with 2.0


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ACKNOWLEDGEMENTSThe suppo rt o f th i s research by the Department o f Energy, underC ontract No. ET-78-G-01-3316, i s g ra te fu l l y acknowledged.

REFERENCES1. D.W. van K revelen, "Coal: T ypology, Chemistry, P hysics, and C on s titutio n",2. H.H. Lowry, "chemistry o f Coal U ti l iz a ti o n ", Wiley, New Y ork, 1945, Vol. 1,3. R.M. Baldwin, J .O. Golden, J .H. Gary, R.L. B ain , and R.J . Long, i n "Coal

E ls evi er, Amsterdam, 1961.

Chapter 19.P rocess ing Technology", American I n s ti tu te o f Chemical E ngineers, New Y ork,Vol. 2, p. 128 (1975).

4. R.P. Anderson, x. ,. 130.5. S. Morooka and C.E. Hamrin, J r., Chem. Eng. Science, 8, 21 (1979).6. L. F. A udrieth and J . K le inbe rg, "Non-Aqueous S olvents ", Wiley, New Y ork,7. W.K.T. Gleim, U.S. P atent 4, 120, 664, 1978.8. D.F. Burow, "S ul fu r D iox ide" i n The C hemistry o f Non-Aqueous S olvent9. D.F. Burow, Inorg. Chem., 2, 73 (1972).

1953, C hapter 11.

Systems, J . J . Lagowski, Ed., Vol. 3, 1970, p. 138.

10. R.A. k ye rs , "Coal De s ul fu riz ati on ", Marcel Dekker, New Y ork, 1977.11. "Coal Desulfurization", T.D. Wheelock, Ed., AC S Symposium S eri es No. 64,12. F. F is cher and W . Gluud, Chem. Ber., g , 147 (1916).13. J .W. Lars en and P . Choudhury, J . Org. Chem., ~, 856 (1979).14. "Organic C hemistry o f C oal", J.W. Larsen, Ed., AC S Symposium S eries15. H.L. R etcofs ky and R.A. F ried el i n "S pectrometry o f Fuels", Plenum,16. P. Fischer, J.W. Stadelhofer, and M. Zander, H, , 345 (1978).

ACS, Washington, D.C., 1977.

No. 71, ACS, Washington, D.C. , 1978.New Y ork, 1970, C hapter 6.

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TABLE 1. C ha rac teris tics of Bituminous Coals Treated wi th L iq ui d SO2COAL (PSOC NO.)

194 26 7 2 70 31 9

TypeOr ig inMacerals ( % / v )

V i t r i n i eP . V i t r i n i t eM i c r i n i t eFusi n i eS . Fus in i teResi i eS Dorini te

Elemental Analysis (DAF)%C%H%N%0(d i f f )% S ( to ta l )

organicp yr i t i cs u l f atic

HV BOH

73.312.6

3.32.22.33.61.8

78.235.561.72

10.973.51

1.262.190.07

H VA H VAVA AL

60.9 68.15.3 3.2

15.6 9.18.7 8.63.4 4.61.5 0.83.2 5.0

84.63 83.345.58 5.552.53 1.745.18 6.592.08 2.77(1 .967)a (2.682)a2.01 2.700.02 0.020.05 0.05

LVP A

85.54.21 .o4.34.00.00.5

86.494.571.610.167.170.107.000.07

aAnalyses done in this work.

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TABLE 2. E xperimental R esultsSample Exp. Reacti n Organic

Temp.( "C ) RemovedP S O C No.) No. Wash %S S u l f u r

2 701 ump1 ump1 ump1 ump1 ump1 ump1 ump1 ump1 umppowderd

26 71 umppowderpowder

dd

1941 ump

31 41 ump

150150150150100100150100100

75

75180200

100

100

1.5M NaOH,H203M HC1 ,H20H20.C6H6CC14ace onemu1 t i p l eb

bbmu1ti lemu1ti le

bmu1 t i p l eH20 acetoneH20 ,acetone

bmu1 t i p l e

bmu1tiple

5.7563.8023.5222.6822.6022.3162.0053.0891.9921.397

1.2410.93940.6580

2.134

1.584

25%25%48%

3 7%52%66%

a. F or l i q u i d SO2 rea ction s , 60 min re ac tion time was used and f o r organ icso lven t reac tions , 5 h r was used.b. The mul tip le wash cons isted o f the use o f sequential a l iquots o f acetone,H20, 3.8 M HN03, H20, acetone (see text).c. The S02/benzene s o luti on was s. : l (vo l ) .d. Lump coal was crus hed and ground t o -60 mesh.

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hWNV0v,Lcm0

4-0uumuxW0v,-030-

N

.r

.rcW.c4-0

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B ..

. . . . . .

I

I..6 9 PPm

FIGURE 3. Nuclear magnetic resonance spectra o f the l iquid SO2 extract o fcoal PSOC 267 ( C D C 1 , ,solution, 5 mm tube). A . l 3 C nmr spectrum,proton noise decoupled, 2000 pulses 8. 'H nmr spectrum, 10 pulses.

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E valuation of Oxydesulfurization Processes fo r CoalI . The E ffect of the Ames P rocess on Model O rganosulfur Compounds

L . W. Chang, W. F . Goure, T . G . Squires, and T . J . BartonAmes Laboratory, US DO E and Department o f Chemistry

Iowa State UniversityAmes, Iowa 50011

INTRODUCTIONOne o f the main obs tacles t o the use of coal as an a lte rn a te energy source i s

that i t contains su lfu r which contributes to a i r po l l uti on when the coal i s burned.I t i s estimated that o nly few percent of coals i n the United States wi l l be able tomeet EPA S O emission standards ( I ) . A lti ough some chemical procedures have beenreported to be ef fe c tiv e fo r de sul furiz ation of coals, most, i f not a l l , of the s u l -fur tha t i s removed i s inorganic. There i s l i t t l e information about what ac tua ll yhappens to the organic s ul fu r when coals ar e subjected to these process conditions.A major reason f o r t h i s ignorance i s the la ck o f info rmation about the nature anddi s tri buti on o f the organosulfur func tional groups in the coal.sulfur can be removed by oxidative processes (2 -6) . Wheelock, e t. a l . ( 2 ) reportedthat under the fo ll owing co ndi tions : 150OC, 2 0 0 psig 0 0 . 2 M aq. NaZC03, 1 hour;up to 40% o f the organic s ul fu r can be removed from coa jwithout significantly re-ducing the recovery o f combustible organic matter.process in the des ulfuriz ation o f coal. Instead of using coal, model organosulfurcompounds were subjec ted t o Ames process cond it io ns . Our approach i s based on theassumption that a definitive knowledge o f the organos ulfur func tiona l groups andthe i r d is t r ibut io n in coal i s not a prerequis i te fo r invest igating the v ia b i l i ty o fdes ulfu riz atio n processes. Thus, i t i s s uf fi ci en t to measure the propensity o f arepresentative spectrum o f organos ulfur model materia ls toward de sul fur iz ati on underprocess conditions.

I n our study, the fo ll ow ing organos ulfu r compounds have been subjected to Amesprocess co nditions e it he r by themselves o r i n the presence of coal. For comparison,some model s u l fur compounds were also run under the same conditi ons except that n i -trogen was used in place o f oxygen. The re sul ts o f our study are summarized inTables I and 1 1 .

2

Recently, several workers have reported tha t organi c s ulf ur as wel l a s inorganic

In th is paper we wish t o re port our evaluation of the effectivenes s o f th i s Ames

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E X P E R IMENTALReactions i n the Absence of Coal

The reactio ns were run ei the r i n an 1 l i t e r o r a 300 m l autoclave. In a typi ca lrun, approximately 5 g (f or the I l i te r autoclave) or 1 gram ( fo r the 300 ml auto-clave) of orga nic sul fi de was placed in a glass li ne r of an autoclave. A fte r adding300 m l ( I 1 autoclave) or 50 ml (300 m l autoclave) o f 0.2M aqueous sodium carbonateso lutio n, the rea ctor was sealed, flushed with N2, and heated as rapidly as possibleto 150OC. A fte r the rea cto r had equi li bra ted at 15OoC (10-15 minutes), the systemwas pressurized to 200 ps ig with oxygen and the reactor was flushed wi th a slowstream of oxygen fo r 3 minutes. A col d t rap was connected to the vent tube o f theautoclave to c ol lec t the s tartin g su lf i de (usually a small amount) which escapedfrom the reactor during the f lushing process (the co ll ec ted s ul fi de was combinedwi th the reactio n mixture i n the autoclave a ft e r the reac tion ). The reactor wasthen sealed, and temperature (I5O0C), s t i r r i n g (1500 rpm) and pressure (200 psig)were maintained fo r one hour. During the i n i ti a l pres suri za tion and the fi r s t 20-30 minutes o f the reaction, coo ling o f the reactor wi th water was sometimes required.perature and the contents werepoured in to a beaker. The rea cto r and the glas s l in erwere washed wi th benzene and wi th water. The re ac tion mixture and these washingswere combined and extracted wi th benzene, and the benzene extract was dr ied (Na SO4)and fi lte re d. To the reactions run in the 300 m l autoclave an in terna l standar8 wasadded di rec tl y t o the dri ed benzene ex tra ct and the solu tion was analyzed by gaschromatography ( G C ) t o determine the quantity o f sta rting s ulf ide l e f t and vo la ti l ecompounds formed in the reaction. G C response factors for the sulfides, productsand the s tandards were generated in the form o f c a l ib ra ti on tabl e using standard so-lu tio ns containing the sul fi de , products and the standard. For the reac tions run i nthe 1 l i t e r autoclave, the volume o f dri ed and f i l te re d benzene extract was adjustedt o 500 rnl , and a 50 m l of ali quot o f the benzene solu tion was withdrawn. An in ter-na l s tandard was added t o the 50 ml so lution ; the sol uti on was analyzed wi th G C .s ul fi de reaction mixture was ac id if ie d wit h concentrated hydro chl ori c ac id, and wash-ed with benzene.af fo rd a residue which N M R and I R ana lys is showed to 6e benzoic acid.aqueous layer was evaporated to dryness, and the res idue was analyzed by N M R , IR,and UV spectroscopy.Reaction in the P resence o f Coal Under Oxygen or Under N itrogen Atmosphere

A fte r one hour, the heater was turned of f ; the reactor was cooled t o room tem-

The extracte d aqueous layer of the benzyl phenyl s ul fi de o r the benzyl methylThe benzene washings were dr ied (Na SO4) and fl as h evaporated to

The remaining

The coal used was Iowa coal (L ovi l ia , 200 mesh) and was dried at llOC overnight.The reactions i n the presence o f coal were run in a 300 m l autoclave. The rea ctio nprocedures were the same as those mentioned above except that E .0 g of coal wasadded to the reaction mixture fo r each run. A fte r the reac tion, the rea ctio n mixtureand washings were combined and f i l te re d , and the f i l t r a te was extra cted with benzene.The coal co ll ec ted wi th f i l t r a t i o n was washed wi th acetone, then benzene severaltimes.and analyzed with GC using internal standards.The benzene and the acetone-benzene extra cts were combined, dried (Na2S04)

RESULTS AND DISCUSSIONTables I and I I demonstrate that among the model compounds that we s tudied, onl y

Thiophenol was converted to phenyl d i s ul f ide which was re s is tantthiophenol and compounds conta ining a benz ylic s ul fi de linkage were oxid iz ed to anappreciable extent.t o further oxida tion . Benzyl phenyl s ul fi de was oxid iz ed and cleaved to give benzlde-hyde, benzoic ac id and benzenesul fonic ac id; benzyl methyl sulfide gave similar re-sults . The other model compounds were unreactive under the Ames proces's conditionseither by themselves or in the presence of coa l. Even i n the presence o f coal , morethan 70% of the sta rt ing sul fi de was recovered. The reduced recoverie s o f s ta rti ng

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Table I . Reaction Results o f Compounds Ru n Under the Ames Process C onditionsin the Absence o f Coala

Compound Recovered Y ie ld (% )o f S tarting S ulfide Product-------Benzothiophene 87Dibenzothiophene 96Th iphenol 0Phenyl s ul fi de 98Phenyl methyl s ul fi de 89

- --- - --Phenyl Disulfide

- - --- -- - -- -- -

Benzyl methyl su lf id e

Benzyl phenyl sul fi de

36

2 9

Benzoic acidBenzaldehydeMethanesulfonic acidBenzoic acidBen za 1 de hydeBenzenesulfonic acid

--- - - --N-Octyl s ulf ide 90a Ames process cond iti ons : 150C, 200 psig 02, 0.2M aqueous Na C O 1 hour.2 3

Table I I . Reaction Results of Compounds Run Under the Ames ProcessaC ondition in the Presence o f Coal b

Compound

DibenzothiophenePhenyl s ul fi deBenzyl methyl s u l fi deN-octyl sulf ide

Recovered Y ie ld (% )of Start ing Sul f ide

NC 021!- -83 7676 7475 13

a2_a Ames process cond iti on s : 15OoC, 2 0 0 psig 02, 0.2M aqueous Na2C0 , 1

hour. blows L ov il i a Coal. CR eaction run under nitrogen atmosJ here.Reaction run under oxygen atmosphere.167


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materials in the presence o f coal (see Table I I ) can be attri bu ted t o absorption o fthe organo su lfur compound by the microporous s truc ture of coal and the mechanicalloss associated with working up the reaction mixture. T hi s hypothesis was confirmedby the correspondingly low recoveries of s ta rti ng sul fi de s from reactions run i nthe presence o f coal under ni trogen atmosphere--an ine rt atmosphere. Furthermore,no oxidation products were detected i n the reactio n mixtures. C lea rly, of the com-pounds inves tigated thus f ar, onl y benzyl s ul fi de s and thiophenol underwent anychemical reac tion, and ( the benzyl sul fi de s were the onl y compounds in which carbons ul fu r bond cleavage occurred.

The base-catalyzed rea ctio n of compounds co ntai ning a benz yli c sul fi de linka gewi th molecular oxygen has been stud ied under a va r ie ty of conditions. Wallace et.-l . (7) repo rted tha t benzyl phenyl s ul fi de can be oxi diz ed wi th molecular oxygen i n2 M potass ium t-butoxide-HMPA a t 80C to y i e l d benzoic ac id.that the reaction proceeded via the formation of an a-carbanion followed by reactionbetween the ion and oxygen.

The authors proposed

@-CH -S-@ base > 0-?H-S-@2> @-c-s -g@-EH-s-Q Io-o-

The res ul ting a- peroxide anion can then decompose in either a stepwise or concertedmanner to form benzaldehyde and benzenesulfenate which are oxi diz ed to the corres-ponding carbo xylic and s ulf on ic acids. In the f i r s t step of th i s mechanism, thea-carbanion is s ta bi l i z ed by the d-o rbital of the adjacent dival ent s ul fu r atom.

0 -

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We beli eve that a s imi la r mechanism i s involved i n the oxidatio n o f benzyl phenyls ul fi de under Ames process condi tions .

Oxydes ulfuriza tion o f the organic s ulf ide s in coal has been formulated as atwo-step process (8): I . S elective oxidation o f the s ulf ur t o sulfoxides and S U I -fones with the l a tte r as the favorable product; and 2 . Thermal decomposi tion o fthe oxidation products, usually under basic conditions.

Step 1 .R 0R \ '&R"'s - ' / s = o - , / \o

Step 2 .

or . A>ydrocarbons + SOx

I n thi s formulation, the reaction is in iti ate d by oxidation of the su lfu r and, infa ct, i s made poss ible by thi s oxida tion which resu lts i n pola riz ati on and weakeningo f the carbon t o s ul fu r bonds ( 8 ) .

We f ind no evidence to support t hi s hypothesis; oxidatio n o f the s ul fu r was de-tected only i n thiophenol and in the benzyl su lfi des . In the f i r s t case, oxida tiono f mercaptans t o di s ul fi de s i s a f a c i l e re action known to occur under condi tionssuch as the Ames process. No further oxidation o f the di s ul fi de was detected. Inthe l a tte r case, we submit that carbon-s ulfur bond cleavage i s i ni ti a te d by oxida -ti ve attack at the benzyl pos ition instead o f at s ul fur . This postula te i s supportedby our recent disc overy tha t, under Ames process cond itio ns , fluorene was oxidi ze dra pi dl y and qua nti ta tive ly to fluorenone whi le dibenzothiophene was removed unchangedfrom the same reac tion mixture.a substantial impact on the development of processes for the oxydesulfurcoal . We intend to inves tigate th i s phenomenon and explore methods fo r

Oxidation o f benzylic carbon hydrogen bonds

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