Coal Liquefaction Under Atmospheric Pressure - American Chemical

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ISAO MOCHIDA and K. TAKESHITA Research Institute of Industrial Science, Kyushu University 86, Fukuoka 812, Japan

Liquefaction of coals has been extensively investigated in the recent time to synthesize liquid fuels of petroleum substituent (1). The processes for liquefaction proposed are classified into three major groups. They are direct hydrogenation of coal under high hydrogen pressure, the solvent refining of coal, and the hydrogenation of liquid produced by dry distillation of coal. Among them, the solvent refining may be the most s k i l l f u l method for the largest yield of coal liquefaction under the moderate conditions (2). This process may be further subdivided into two categories. First idea consists of extraction of coal molecules, using suitable solvents such as anthracene o i l or toluene under super c r i t i c a l conditions (3). Another one depends on the moderate hydrogenation of coal molecule using solvents of hydrogen transfer ability such as hydrogenated anthracene o i l (4) and tetraline (5) under medium hydrogen pressure. The present authors studied the solvolytic liquefaction process (6,7) from chemical viewpoints on the solvents and the coals in previous paper (5). The basic idea of this process is that coals can be liquefied under atmospheric pressure when a suitable solvent of high boiling point assures the a b i l i t y of coal extraction or solvolytic reactivity. The solvent may be hopefully derived from the petroleum asphaltene because of i t s effective u t i l i z a t i o n . Fig. 1 of a previous paper (8) may indicate an essential nature of this process. The liquefaction activity of a solvent was revealed to depend not only on i t s dissolving ability but also on i t s reactivity for the liquefying reaction according to the nature of the coal. Fusible coals were liquefied at high yield by the aid of aromatic solvents. However, coals which are non-fusible at liquefaction temperature are scarcely 0-8412-0587-6/80/47-139-259$05.00/0 © 1980 American Chemical Society Whitehurst; Coal Liquefaction Fundamentals ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

COAL LIQUEFACTION FUNDAMENTALS

260

l i q u e f i e d with the non-reactive solvent. This fact i n d i c a t e s t h e importance o f s o l v o l y t i c r e a c t i v i t y i n the l i q u e f a c t i o n such c o a l s . This conclusion corres ponds t o t h e f a c t t h a t t e t r a l i n e o r hydrogenated a n t h racene o i l a s s u r e d t h e h i g h l i q u e f a c t i o n y i e l d r e g a r d l e s s o f t h e c o a l r a n k s (4./.5) , a l t h o u g h t h e p r o c e s s e s r e q u i r e some h i g h p r e s s u r e . In t h e p r e s e n t s t u d y , t h e l i q u e f a c t i o n a c t i v i t i e s o f p y r e n e , i t s d e r i v a t i v e s , and d e c a c y c l e n e w i t h c o a l s of s e v e r a l ranks are s t u d i e d t o a s c e r t a i n the previous i d e a s o f l i q u e f a c t i o n mechanism and t o d e v e l o p n o v e l l i q u e f a c t i o n p r o c e s s under a t m o s p h e r i c p r e s s u r e . The c o a l s used i n t h e p r e s e n t study a r e n o n - f u s i b l e o r f u s i b l e a t r e l a t i v e l y h i g h temperature, and then gave s m a l l l i q u e f a c t i o n y i e l d w i t h pyrene o f a n o n - s o l v o l y t i c s o l v e n t a t 370°C. Experimental Coals. The c o a l s used i n t h e p r e s e n t s t u d y a r e l i s t e d i n T a b l e 1, where some o f t h e i r p r o p e r t i e s a r e a l s o summarized. They were g r a t e f u l l y s u p p l i e d from Nippon S t e e l Co., Nippon Kokan Co., and N a t i o n a l I n d u s t r i a l R e s e a r c h L a b o r a t o r y o f Kyushu.

0

Liquefaction Solvents. The s o l v e n t s used i n t h e p r e s e n t study a r e l i s t e d i n T a b l e s 2 and 3. A l k y l a t e d and h y d r o g e n a t e d p y r e n e s were s y n t h e s i z e d by F r i e d e l C r a f t s and B i r c h r e d u c t i o n , r e s p e c t i v e l y . D e t a i l s have been d e s c r i b e d i n a n o t h e r p l a c e ( 9 ) . P r o c e d u r e and A n a l y s i s . A p p a r a t u s used i n t h i s experiment c o n s i s t e d o f a r e a c t o r o f pyrex g l a s s ( d i a meter 30 mm, l e n g t h 250 mm, volume 175 ml) w i t h a s t i r r i n g b a r and a c o l d - t r a p . A f t e r 1 Ό g o f c o a l and d e s c r i b e d amount o f t h e s o l v e n t were added i n t h e r e a c t o r , o f which w e i g h t was p r e v i o u s l y raeasered, t h e r e a c t o r was h e a t e d i n a v e r t i c a l e l e c t r i c f u r n a c e under N2 gas f l o w . The temperature was i n c r e a s e d a t t h e r a t e o f 4°C/min, and was k e p t a t t h e p r e s c r i b e d temperature f o r 1 h r . The w e i g h t c a l c u l a t e d by s u b s t r a c t i n g t h e w e i g h t o f t h e r e a c t o r from t h e t o t a l w e i g h t was d e f i n e d t o be r e s i d u a l y i e l d (remaining c o a l and s o l v e n t ) . The w e i g h t o f o i l and s u b l i m e d m a t t e r c a p t u r e d i n t h e t r a p was d e f i n e d ' o i l y i e l d ' . The d i f f e r e n c e between t h e w e i g h t o f c h a r g e d s u b s t a n c e s and t h e r e s i d u e p l u s o i l y i e l d s was d e f i n e d 'gas y i e l d ' which c o n t a i n e d t h e l o s s during the experiment. The gas and o i l y i e l d s were u s u a l l y l e s s than 20% under t h e p r e s e n t c o n d i t i o n s . The r e s i d u a l p r o d u c t i n t h e r e a c t i o n was ground

Whitehurst; Coal Liquefaction Fundamentals ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

14.

MOCHiDA A N D TAKESHiTA

Atmospheric

261

Pressure

and s t i r r e d i n 100 ml of q u i n o l i n e f o r 1 hr a t room temperature, and f i l t e r e d a f t e r c e n t r i f u g a t i o n . This e x t r a c t i o n p r e c e d u r e was r e p e a t e d u n t i l the f i l t r a t e became c o l o r l e s s ( u s u a l l y 2^4 t i m e s ) . The quinoline i n s o l u b l e (QI), thus o b t a i n e d , was washed w i t h benzene and acetone and then d r i e d f o r w e i g h i n g . The c o l l e c t e d f i l t r a t e was e v a p o r a t e d t o d r y n e s s i n vacuo and washed w i t h acetone f o r w e i g h i n g . The degree o f the s o l v o l y t i c l i q u e f a c t i o n was d e s c r i b e d w i t h two ways o f e x p r e s s i o n , l i q u e f a c t i o n y i e l d (LY) and l i q u e f y i n g e f f i c i ency (LE), which were d e f i n e d by e q u a t i o n s (1) and (2) , respectively. QI and the c o a l f e d i n t h e s e e q u a t i o n s were m o i s t u r e and ash f r e e (maf) w e i g h t s . ρ s L i q u e f a c t i o n Y i e l d (LY) % = (1- ^ o a ^ f e d * X

p

OI -OI

Liquefying

Efficiency

(LE)

% =

(1- ^ — ^ — ) QI°

1 0 0

( 1 )

s

X 100

(2)

Ρ s c where QI^, QI , and QI are w e i g h t s o f q u i n o l i n e inso l u b l e i n the r e s i d u a l p r o d u c t , i n the o r i g i n a l s o l v e n t , and i n the h e a t - t r e a t e d c o a l a t the l i q u e f a c t i o n tempe r a t u r e w i t h o u t any s o l v e n t , r e s p e c t i v e l y . LE may d e s c r i b e the i n c r e a s e d y i e l d of l i q u e f a c t i o n by u s i n g the s o l v e n t , i n d i c a t i n g i t s e f f i c i e n c y f o r the l i q u e f a c t i o n . Results L i q u e f a c t i o n of f u s i b l e c o a l a t h i g h t e m p e r a t u r e . The l i q u e f a c t i o n of Itmann c o a l , of which s o f t e n i n g p o i n t and maximum f l u i d i t y temperature are 417° and 465°C, r e s p e c t i v e l y , was c a r r i e d out a t s e v e r a l tempe r a t u r e s u s i n g d e c a c y c l e n e as a l i q u e f a c t i o n s o l v e n t . The r e s u l t s are shown i n F i g . 2, where the QI y i e l d was adoj^ted as a measure o f l i q u e f a c t i o n e x t e n t . Because the s o l u b i l i t y of d e c a c y c l e n e i n q u i n o l i n e was rather l i m i t t e d , the QI c o n t a i n e d a c o n s i d e r a b l e amount o f decacyclene. L i q u e f a c t i o n o f t h i s c o a l proceeded s c a r c e l y below 420°C o f the s o f t e n i n g temperature w i t h t h i s s o l v e n t as w e l l as p y r e n e . Above t h i s tempera t u r e , the QI y i e l d d e c r e a s e d s h a r p l y w i t h the i n c r e a s i n g l i q u e f a c t i o n temperature u n t i l the r e s o l i d i f i c a t i o n temperature o f the c o a l . The maximum LY o b s e r v e d a t t h i s temperature was e s t i m a t e d 67%, d e c a c y c l e n e b e i n g assumed uncharged under the c o n d i t i o n s . Above the r e s o l i d i f i c a t i o n temperature, the QI y i e l d i n c r e a s e d sharply. The c a r b o n i z a t i o n may s t a r t . D e c a c y c l e n e was known u n r e a c t e d a t 470°C i n i t s s i n g l e h e a t - t r e a t m e n t (10) , and i n i t s c o c a r b o n i z a t i o n w i t h some c o a l s (11) although i t i s f u s i b l e . C o c a r b o n i z a t i o n of f u s i b l e r


262


Table 1 Properties Proximate analysis (wt%)

C o a l s and t h e i r p r o p e r t i e s coal

ash v o l a t i l e matter f i x e d carbon C H ultimate analysis Ν (wt%) S O(diff) soften.temp.(°C) p l a s t i c i t y max.fluid.temp.(°C) analysis max.fluid.(ddpm) f i n a l temp.(°C)

Itmann 7.,3 19. 9 72.,8 90.,1 4.,6 1.,3 0.,5 3.,5 417 465 64 487

West Taiheiyo Kent.14 12.,8 53.,0 34.,2 79.,0 5.,1 1.,7 4.,6 9.,6 387 425 45 445

10. 1 45. 9 37. 7 77. 8 6. 0 1. 1 0. 2 14. 9 non L— fusible

Table 2 C o a l l i q u e f a c t i o n by pyrene d e r i v a t i v e s ( r e a c t i o n temp.=370°C, s o l v e n t / c o a l = 3 / l ) ** ** residue(%),distilate(%) L.Y. L.E. s o l v e n t n* coal QI QS o i l gas West 0 17 85.1 9.2 0.8 4.9 Kent. none 3 0 Itmann 97.5 0.0 0.8 1.7 0 16 T a i h e i y o 85.4 2.2 12.4 0.0 West 24 69.9 8 4.2 19.9 6.0 Kent*** pyrene 0 23 18 20.4 Itmann 75.2 3.1 1.3 25 11 3.2 T a i h e i y o 19.3 75.0 2.5 West hydro80 76 73.4 7.6 9.4 9.6 Kent. pyrene 68 69 9.1 Itmann 5.8 79.6 5.5 (No.l) 83 80 Taiheiyo 6.3 85.0 4.5 4.2 West 26 11 19.3 51.3 12.8 16.5 hexylKent. 0.83 pyrene 17 15 20.9 Itmann 63.1 8.5 7.5 9 25 T a i h e i y o 19.7 56.2 11.8 12.8 West 38 14.4 66.3 3.5 16.1 49 propylKent. 0.85 42 pyrene 43 Itmann 66.3 7.2 14.9 11.6 42 30 T a i h e i y o 15.7 65.7 6.7 11.9 West 80 76 7.6 12.4 79.3 0.7 ethylKent. 0.33 pyrene 58 59 Itmann 11.4 77.8 5.7 5.5 52 42 T a i h e i y o 13.4 76.8 6.9 2.9

—

L.E.=Liquefying E f f i **L.Y.=Liquefaction Y i e l d (% ) ; ciency(%) * ** r e a c t i o n temp.=390°C


MOCHiDA AND TAKE SHIT A

Atmospheric

10* 10* ]& 10 Max.Fluidity (ddpm)

b

Fuel

Figure 2.

Pressure

263

Figure 1. Liquefaction yields vs. maxi mum fluidities in the fused state of coal: (Φ), solvent (SRC pitch benzene soluble); (O), pyrene; (ΦΛ no solvent. Coal .sol vent ratio = 1:3; reaction temperature = 390°C(&).

Effect of reaction temperature on coal liquefaction yield. Coal = It mann; solvent = decacyclene; solventxoal ratio = 3:1.


264


c o a l w i t h d e c a c y c l e n e d e v e l o p e d a homogeneous o p t i c a l t e x t u r e i n the r e s u l t a n t c o k e , i n d i c a t i n g t h e i r mutual solubility (11). L i q u e f a c t i o n of c o a l s i n a l k y l a t e d and h y d r o g e n ated pyrenes. T a b l e 2 shows l i q u e f a c t i o n a c t i v i t y of a l k y l a t e d and hydrogenated pyrenes a t 3 7 0 ° C , r e s p e c tively. A l t h o u g h h e x y l p y r e n e showed j u s t the same l i q u e f a c t i o n a b i l i t y as p y r e n e , p r o p y l a t i o n and e t h y l a t i o n c e r t a i n l y improved the l i q u e f a c t i o n a c t i v i t y o f pyrene w i t h t h e s e c o a l s o f t h r e e d i f f e r e n t r a n k s . It i s o f v a l u e t o note t h a t e t h y l p y r e n e showed LY o f 80% w i t h West-Kentucky c o a l , which was s i g n i f i c a n t l y h i g h e r than w i t h o t h e r c o a l s . H y d r o g é n a t i o n improved q u i t e s i g n i f i c a n t l y the l i q u e f a c t i o n a c t i v i t y o f pyrene w i t h t h e s e c o a l s . The LY v a l u e s w i t h T a i h e i y o and West-Kentucky c o a l s r e a c t e d to 80%, a l t h o u g h the v a l u e w i t h Itmann i s r a t h e r low. The e f f e c t of h y d r o g é n a t i o n e x t e n t on the l i q u e f a c t i o n a c t i v i t y was summarized i n T a b l e 3. As the Table 3 E f f e c t o f h y d r o g é n a t i o n e x t e n t on the l i q u e f a c t i o n a c t i v i t y ( r e a c t i o n temp.= 3 7 0 C, s o l v e n t / c o a l = 3 / l ) solvent No. 1 h y d r o - No. 2 pyrene No. 3 No. 4

n* 2.2 2.8 4.3 4.7

Itmann L.Y. L.E. (%) (%) 68 69 78 78 72 71 72 71

Taiheiyo L.Y. L . E . (%) (%) 83 80 90 88 85 82 83 79

L.Y.=Liquefaction Yield L.E.=Liquefying Efficiency * η =number o f hydrogen atoms i n t r o d u c e d / o n e pyrene m o l e c u l e number o f hydrogen atoms i n t r o d u c e d p e r one pyrene m o l e c u l e v a r i e d from 2.2 t o 4.7 by u s i n g a v a r i a b l e amount o f l i t h i u m i n B i r c h r e d u c t i o n . The l i q u e f a c t i o n a c t i v i t y o f hydrogenated pyrene was a f f e c t e d s l i g h t l y , r e a c h i n g the maximum around t h r e e hydrogen atoms p e r one m o l e c u l e . I t i s o b v i o u s l y observed t h a t LY was always l a r g e r w i t h T a i h e i y o than Itmann. S t r u c t u r a l change o f s o l v e n t s and c o a l s a f t e r the liquefaction reaction. To a n a l y s e s t r u c t u r a l change o f s o l v e n t s and c o a l s i n the l i q u e f a c t i o n r e a c t i o n , the s o l v e n t and c o a l s h o u l d be s e p a r a t e d . Because the s e p a r a t i o n was r a t h e r d i f f i c u l t , i t was


14.

MOCHiDA A N D TAKESHITA

Atmospheric

Pressure

265

assumed t h a t the benzene s o l u b l e and i n s o l u b l e f r a c t i o n s a f t e r the l i q u e f a c t i o n were d e r i v e d from the s o l v e n t and c o a l , r e s p e c t i v e l y . The p r o c e d u r e can be s h e m a t i c a l l y d e s c r i b e d i n the f o l l o w i n g : Gas,

Oil

,

/ Coal& fouinoline 1 SolventI Soluble

Benzene ^ / Λ

S

ΐ

o

η

l

\ SiSS5:

Fractionation

scheme o f

Κ

u

1

b

(Solvent)

ΰ

l

e

( U n r e a l

Coal,

l i q u e f a c t i o n product

T h i s assumption was v e r i f i e d by the f o l l o w i n g f a c t . The amount o f BS r e c o v e r e d i n the l i q u e f a c t i o n o f T a i h e i y o c o a l w i t h pyrene was 73.3% as shown i n T a b l e 4. T h i s v a l u e c o r r e s p o n d s t o 97.7% o f the s t a r t i n g amount of pyrene and the BS f r a c t i o n a t the same time showed the same NMR p a t t e r n t o t h a t o f p y r e n e . This i s also t r u e f o r h y d r o p y r e n e , however the r e c o v e r e d BS was r a t h e r low f o r e t h y l p y r e n e , i n d i c a t i n g i t s r e a c t i v i t y . The r e c o v e r y p e r c e n t a g e s of c o a l and s o l v e n t ( B I / coal fed, BS/solvent fed, respectively) calculated based on the above assumption a r e summarized i n T a b l e 4. They were more than 85% e x c e p t f o r the s i g n i f i c a n t l y low v a l u e f o r the c o a l r e c o v e r y when h y d r o p y r e n e was used as t h e s o l v e n t . In the l a t t e r c a s e , some e x t e n t o f the c o a l may be c o n v e r t e d i n t o the benzene soluble. N e v e r t h e l e s s , a n a l y s e s o f BS and BI f r a c t i o n s may i n f o r m the s t r u c t u r a l change of c o a l and s o l v e n t a f t e r the l i q u e f a c t i o n . F i g u r e s 3 and 4 show the NMR s p e c t r a o f benzene s o l u b l e s a f t e r the l i q u e f a c t i o n r e a c t i o n u s i n g h y d r o pyrene and e t h y l p y r e n e , r e s p e c t i v e l y , t o g e t h e r w i t h t h o s e o f the s o l v e n t s b e f o r e l i q u e f a c t i o n f o r compar ison. The keys f o r i d e n t i f i c a t i o n o f hydrogen o b s e r v e d i n the s p e c t r a a r e summarized i n F i g . 5. The BS d e r i v e d from h y d r o p y r e n e a f t e r the l i q u e f a c t i o n l o s t the resonance peaks a t 2 . 5 , 3.2 and 4.0 ppm e x t e n s i v e l y , a l t h o u g h peaks a t 2.0 and 2.8 ppm remanined unchanged as shown i n F i g u r e 3. In c o n t r a s t , there was e s s e n t i a l l y no change i n the NMR s p e c t r a o f e t h y l p y r e n e and i t s BS d e r i v a t i v e as shown i n F i g u r e 4, i n d i c a t i n g t h a t the BS d e r i v a t i v e c o n t a i n e d unchanged ethylpyrene. However, the r e l a t i v e l y low BS r e c o v e r y o f t h i s case s u g g e s t s t h a t the c o n v e r s i o n o f t h i s


Figure 3.

NMR spectra of (a) hydropyrene, (b) its BS derivative after the liquefaction process, and (c) hydropyrene heated at 400°C



Atmospheric

Pressure

267

(a)

Figure 4.

NMR spectra of (a) ethylpyrene and (b) its BS derivative after the liquefaction. For liquefaction conditions, see Table 4.


268


compound i n t o the c a r b o n i z e d m a t t e r may i n c r e a s e the BI y i e l d i n comparison w i t h o t h e r c a s e s as shown i n T a b l e 4. T a b l e 5 shows the u l t i m a t e a n a l y s i s o f benzene i n s o l u b l e f r a c t i o n s a f t e r the l i q u e f a c t i o n . H/C r a t i o s of t h e s e f r a c t i o n s were s i m i l a r when no s o l v e n t o r pyrene was u s e d , however when e t h y l p y r e n e and h y d r o pyrene were u s e d , the v a l u e s were s i g n i f i c a n t l y low and high, respectively. The h y d r o g é n a t i o n o f c o a l by the hydrogen t r a n s f e r from the hydrogen d o n a t i n g s o l v e n t i s s t r o n g l y s u g g e s t e d i n the l a t t e r c a s e . The low H / C v a l u e i n the case o f e t h y l p y r e n e may be e x p l a i n e d i n terms of c e r t a i n e x t e n t o f c a r b o n i z a t i o n , as s u g g e s t e d by the low r e c o v e r y o f the s o l v e n t shown i n T a b l e 4. Discussion In a p r e v i o u s paper (_5) , the a u t h o r s d e s c r i b e d the l i q u e f a c t i o n mechanism a c c o r d i n g t o the p r o p e r t i e s o f the c o a l and the s o l v e n t . The c o a l was c l a s s i f i e d i n t o two c a t e g o r i e s . (1) f u s i b l e a t the l i q u e f a c t i o n t e m p e r a t u r e , (2) n o n - f u s i b l e a t the l i q u e f a c t i o n t e m p e r a t u r e . The f u s i b l e c o a l s can g i v e a h i g h l i q u e f a c t i o n y i e l d i f the h i g h f l u i d i t y d u r i n g the l i q u e f a c t i o n i s m a i n t a i n e d by the l i q u e f a c t i o n s o l v e n t t o p r e v e n t the c a r b o n i z a tion. The p r o p e r t i e s o f the s o l v e n t r e q u i r e d f o r the h i g h y i e l d w i t h t h i s k i n d of c o a l a r e m i s c i b i l i t y , low v i s c o s i t y , r a d i c a l quenching r e a c t i v i t y and t h e r m a l s t a b i l i t y not t o be c a r b o n i z e d a t the l i q u e f a c t i o n temperature as r e p o r t e d i n l i t e r a t u r e s (12). In c o n t r a s t , the n o n - f u s i b l e c o a l r e q u i r e s the s o l v a t i o n ( e x t r a c t i o n ) o r s o l v o l y t i c r e a c t i o n t o be liquefied. The s o l v a t i o n o f n o n - p o l a r o r g a n i c compounds i n c l u d i n g the p i t c h may be r a t h e r l i m i t t e d , so t h a t the s o l v o l y t i c r e a c t i o n i s n e c e s s a r y f o r the h i g h l i q u e f a c t i o n y i e l d between the c o a l and the s o l v e n t . The r e a c t i o n may c o n t a i n h y d r o g é n a t i o n , a l k y l a t i o n , and d e p o l y m e r i z a t i o n o f c o a l m o l e c u l e s a s s i s t e d by the l i q u e f y i n g s o l v e n t . Through t h e s e r e a c t i o n s , c o a l m o l e c u l e s can be c o n v e r t e d t o be f u s i b l e o r s o l u b l e i n the s o l v e n t . The p r e s e n t r e s u l t s a r e w e l l u n d e r s t o o d by the above mechanism. Itmann which i s f u s i b l e a t r e l a t i v e l y h i g h temperature was n o t l i q u e f i e d below 4 2 0 ° C w i t h a n o n - s o l v o l y t i c s o l v e n t such as p y r e n e , however i t was s i g n i f i c a n t l y l i q u e f i e d a t 4 8 0 ° C o f i t s maximum f l u i d i t y temperature i n decacyclene o f a s t a b l e aromatic compound. With s o l v o l y t i c s o l v e n t s , the f l u i d i t y of the c o a l


14.


Atmospheric

269

Pressure

T a b l e 4 Benzene e x t r a c t i o n o f s o l v o l y s i s pitches (coal=Taiheiyo, reaction t e m p . = 3 7 0 ° C , s o l v e n t / c o a l = 3 / l )

solvent none hydropyrene (No.2) ethylpyrene pyrene

distilate residue gas oil BI BS (%) (%) (%) (%) 3.2 86.4 10.0 0.5

recovery* coal solvent (%) (%) 86.4

18.4

70.6

3.6

7.4

74.6

94.1

23.9

64.0

7.9

4.2

96.0

85.3

22.4

73.3

0.9

3.4

89.6

97.7

Figure 5.

-

Proton identification

Table 5

U l t i m a t e a n a l y s i s o f benzene i n s o l u b l e p a r t of s o l v o l y s i s p i t c h (coal=Taiheiyo, reaction t e m p . = 3 7 0 ° C s o l v e n t / c o a l = 3 / l ) /

solvent none pyrene ethylpyrene hydropyrene

others(%) H/C 18.26 0.840 0.849 16.75

C(%) 75.05 76.25

H(%) 5.29 5.43

N(%) 1.40 1.53

82.24

4.93

1.80

11.03

0.714

72.47

5.48

1.38

20.67

0.901


270


may n o t be a p r i n c i p a l f a c t o r any more. Taiheiyo, W e s t - K e n t u c k y , and Itmann c o a l s o f t h r e e d i f f e r e n t ranks were s u f f i c i e n t l y l i q u e f i e d w i t h hydropyrene under a t m o s p h e r i c p r e s s u r e a t 3 7 0 ° C r e g a r d l e s s o f t h e i r fusibility. The a n a l y s e s o f hydropyrene and the c o a l b e f o r e and a f t e r the l i q u e f a c t i o n c l e a r l y i n d i c a t e the hydrogen t r a n s f e r from the s o l v e n t t o the c o a l s u b stance. Lower rank c o a l s l o o k t o show r a t h e r h i g h e r r e a c t i v i t y i n such l i q u e f a c t i o n , p r o b a b l y because t h e i r c o n s t i t u e n t m o l e c u l e may have s m a l l e r condensed r i n g . T r a n s a l k y l a t i o n might be e x p e c t e d a n o t h e r k i n d o f the s o l v o l i t i c r e a c t i o n . However, the p r e s e n t r e s u l t s s u g g e s t low p r o b a b i l i t y w i t h a l k y l a t e d p y r e n e s as s u g g e s t e d by the NMR a n a l y s e s . I n s t e a d , the i n c r e a s e d p o l a r i t y by a l k y l group o r the enhanced r e a c t i v i t y o f the c a r b o n i z a t i o n p r e c u r s o r from a l k y l p y r e n e , e s p e c i a l l y e t h y l p y r e n e , may be r e s p o n s i b l e f o r a c o n s i d erable liquefaction y i e l d . The r e c o v e r y o f the s o l v e n t becomes d i f f i c u l t by i t s l a t t e r c o n v e r s i o n as o b s e r v e d i n the p r e s e n t s t u d y . F a i l u r e o f h e x y l p y r e n e as the l i q u e f a c t i o n s o l v e n t may be due t o the easy d e a l k y l a t i o n (13) o r h i g h c a r b o n i z a t i o n r e a c t i v i t y p r o b a b l y c a t a l y z e d by c o a l s . T r a n s a l k y l a t i o n f o r c o a l - l i q u e f a c t i o n may r e q u i r e the a c i d - c a t a l y s t (14) o r h i g h p r e s s u r e (15) . D e t a i l s on the l i q u e f a c t i o n o f s l i g h t l y f u s i b l e c o a l s (West-Kentucky) a r e n o t d i s c u s s e d i n the p r e s e n t study. Rather huge s t o r a g e o f such c o a l s may be most s u i t a b l e f o r f u r t h e r development. A t moment, moderate h y d r o g é n a t i o n i s e x t e n s i v e l y i n v e s t i g a t e d (A) , however the a u t h o r s would p r o p o s e the p o s s i b i l i t y o f t h e i r e x t r a c t i v e l i q u e f a c t i o n by u s i n g the p r o p e r s o l v e n t o r improving t h e i r f u s i b i l i t y . High l i q u e f a c t i o n y i e l d by e t h y l p y r e n e f o r t h i s c o a l i s s u g g e s t i v e . Such l i q u e f a c t i o n may be e c o n o m i c a l l y i n t e r e s t i n g . Further study w i l l be p u b l i s h e d soon (16). Acknowledgement T h i s r e s e a r c h was p a r t l y s u p p o r t e d by the M i n i s t r y o f Trade and I n d u s t r y t h r o u g h the S u n - S h i n e p r o j e c t and p a r t l y by s p e c i f i e d r e s e a r c h p r o j e c t on energy a d m i n i s t r a t e d by the M i n i s t r y o f E d u c a t i o n . Abstract

Atmospheric l i q u e f a c t i o n of coals of three ranks were studied at temperature range of 370~470°C, using decacyclene, pyrene, alkylated pyrene and hydrogenated pyrene as the l i q u e f y i n g solvent. Coal of high


14.

MOCHIDA AND TAKESHITA

Atmospheric Pressure

211

softening temperature was l i q u e f i e d using decacyclene, which i s stable at the temperature. Hydropyrene gave high l i q u e f a c t i o n y i e l d s regardless of the coal rank. S i g n i f i c a n t a c t i v i t y of ethylpyrene i s of value to be noted. The l i q u e f a c t i o n mechanism was discussed by d i s tinguishing the f u s i b l e c o a l from non-fusible one. The importance of s o l v o l y t i c hydrogen transfer i s pointed for the l i q u e f a c t i o n of non-fusible coal under atmospheric pressure. L i t e r a t u r e Cited (1)

(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15)

(a) Yavorsky, P. M. J . Fuel I n s t . Japan, 1976, 55, 143. (b) Van Kravelen, D. W. "Coal" E l s e v i e r Amsterdam, 1961. (c) Oblad, A. G. C a t a l . Rev., 1976, 14 (1), 83. (d) E l l i n g t o n , R. T. " L i q u i d Fuels from C o a l " , Academic Press Inc. 1977. Kamiya, Y. J . Fuel Inst. Japan, 1977, 56, 319. B a r t l e , K. D . ; M a r t i n , T. G . ; W i l l i a m s , D. F . F u e l , 1975, 54, 226, 1979, 58, 413. P o t t , A . ; Brock, H. F u e l , 1934, 13, 91, 125, 154., Ruberto, R. G.;Cronaver, D. C.; J e w e l l , D. M . ; Seshadri K. S. F u e l , 1977, 56, 25. N e a v a l l , R. C. F u e l , 1976, 55, 237. Yamada, Y.;Honda, H . ; O i , S . ; T s u t s u i , H. J . Fuel Inst. Japan, 1974, 53, 1052. Osafune, K . ; A r i t a , S.;Yamada, Y.;Kakiyama H.; Honda, H.;Tagawa, N. J . Fuel I n s t . Japan, 1976, 55, 173. Mochida, I.:Takarabe, A . ; T a k e s h i t a , K. F u e l , 1979, 58, 17. Reggel, L . ; F r i e d e l , R. A.;Wender, I. J . Org. Chem., 1975, 22, 891, Mochida, I.;Kudo, K . ; Takeshita, K. F u e l , 1974, 53, 253, 1976, 55, 70. Mochida, I.;Miyasaka, H . ; F u j i t s u , H . ; T a k e s h i t a , K. Carbon(Tanso), 1977, No. 92, 7. Mochida, I . ; Marsh, H. F u e l , 1979, 58, 626. Mochida, I . ; G r i n t , A.;Marsh, H. F u e l , 1979, 58, 633. Scarah, W. P . ; D i l o n , R. R. Ind. Eng. Chem., Process Design Dev., 1975, 15, 122, Sato, H.; Kamiya, Y., J . Fuel Inst. Japan, 1977, 56, 103. Mochida, I.;Maeda, K . ; T a k e s h i t a , K. F u e l , 1976, 55, 70. Schlosberg, R. H.;Gorbaty, R. H.;Aczel, T. J . Am. Chem. Soc., 1978, 100, 4188. Shibata, M . ; A r i t a , S.;Honda, H. 15th Coal Science


272


Meeting, JAPAN Abstract, 1978, p.26. (16) Mochida, I . ; T a h a r a , Τ . ; I w a m o t o , K . ; F u j i t s u , H.; K o r a i , Y . ; Takeshita, Κ. Nippon Kagakukai Shi (J. Chem. Soc. Japan) i n press (May, 1980). RECEIVED

March 28, 1980.


Coal Liquefaction Under Atmospheric Pressure - American Chemical

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