5 Hydrotreatment and Biological Test of SRC-II Coal Liquid
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DEXTER SUTTERFIELD and W. C. LANNING U.S. Department of Energy, Bartlesville Energy Technology Center, P.O. Box 1398, Bartlesville, OK 74003 R. E. ROYER Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute, P.O. Box 5890, Albuquerque, N M 87115
Distillate coal liquid from the SRC-II process has been hydrotreated at several levels of severity in a bench-scale continuous flow unit at the Bartlesville Energy Technology Center. The purpose was two fold with the immediate goal to survey process conditions with a commercially available catalyst to provide samples upgraded to varied degrees for detailed characterization analyses and investigation for biological activity. Long-range goals are to contribute to a data base to evaluate raw material sources, liquefaction or other production processes, characterization of feedstocks for further refining to transportation and other end-use fuels, selection of refining processes, and estimation of type and quality of end products expected from combinations of these steps. The liquid feed and products have been screened for biological activity by the Ames test at Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico. Experimental Materials and Procedures The SRC-II liquid was obtained from the Pittsburg and Midway Coal Mining Co. The liquid was produced from Material Balance Run No. 77 SR-12 on coal from the Pittsburg seam from Consol's Blacksville No. 2 Mine in West Virginia. The middle (177-288° C) and heavy (288-454°C) distillates were blended to the same ratio as produced by the material balance run, e.g., 75.5 percent middle distillate and 24.5 percent heavy distillate. The feed contained 0.23 wt-pct sulfur, 1.06 wt-pct nitrogen and 3.29 wt-pct oxygen and boiled between 185 and 380° C (5-95 percent) by simulated distillation. The bench-scale hydrogenation unit was designed for operation at up to 3,000 psig and 450° C, with once-through flow of hydrogen, down-flow of gas and liquid over a fixed-bed catalyst. Reactor temperature, pressure, and hydrogen flow and liquid level in the high-pressure product separator were controlled automatically. Liquid product was withdrawn periodically from a low-pressure 0097-615 6/ 81 /015 6-0145$05.00/0 © 1981 American Chemical Society Sullivan; Upgrading Coal Liquids ACS Symposium Series; American Chemical Society: Washington, DC, 1981.
Sullivan; Upgrading Coal Liquids ACS Symposium Series; American Chemical Society: Washington, DC, 1981.
9.68
.962
0.35 1.0
400 325
5,010 980
.06 2.00
.01 .01
.001 .742
8
12.82
.868
0.50 400 3,250 .03
.01
7
.boi
12.39
.877
0.50 375 2,880 .09
6
.01
.001
12.24
.887
0.50 310 970
5
1.58
.02
.700
9.80
.953
0.50 350 2,670
4
.17
.01
.033
11.54
.902
1.0 325
3
1,270
1.65
.02
.631
10.06
.948
0.50 325
2
.59
.01
0.352
10.81
0.921
1,930
-
-
Liquid feed r a t e , LHSV
-
1
3.29
1.057
8.42
1.003
(Feed)
.25
Catalyst Approx. H2 Cons., temperaSCF/bbl ture,°C
Oxygen wt-pct
L i q u i d Product Nitrogen, wt-pct
Sp. g r . , 60°/60°
Sample Period
Sulfur wt-pct
Hydrogen, wt-pct
TABLE I . Process Conditions and R e s u l t s
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Downloaded by PURDUE UNIV on July 6, 2016 | http://pubs.acs.org Publication Date: June 20, 1981 | doi: 10.1021/bk-1981-0156.ch005
5.
SUTTERFIELD ET A L .
Hydr-ctreatment of SRC-II
147
separator, and the combined h i g h - and low-pressure e f f l u e n t gas was sampled f o r a n a l y s i s . The c a t a l y s t was 100 ml of American Cyanamid HDS-3A, a 1/16inch diameter extrudate of nickel-molybdenum-alumina. I t was d i l u t e d w i t h i n e r t , granular alpha-alumina to provide a bed depth of 18 inches i n the middle s e c t i o n of a 0.96-inch ID v e r t i c a l r e a c t o r w i t h a 5/16-inch OD i n t e r n a l thermocouple w e l l . The c a t a l y s t was p r o g r e s s i v e l y more d i l u t e toward the top of the bed to minimize exothermic temperature e f f e c t s , and end s e c t i o n s were packed w i t h alpha-alumina to p r o v i d e f o r preheat and c o o l i n g zones. The c a t a l y s t was p r e s u l f i d e d and operated f o r about 100 hours on a petroleum gas o i l (200-500° C b o i l i n g range, 0.8 wt-pct s u l fur) to check c o n t r o l s and p r o v i d e some c a t a l y s t aging before exposure to the c o a l l i q u i d . Operating c o n d i t i o n s s e l e c t e d as l i k e l y to maintain c a t a l y s t a c t i v i t y and provide the range of upgrading d e s i r e d were 2,000 p s i g pressure, 325 to 400° C, and 0.5 to 1.0 LHSV (volume l i q u i d feed/volume bulk c a t a l y s t / h o u r ) . Hydrogen flow was h e l d constant at a r a t e corresponding to 10,000 SCF/bbl to 0.5 LHSV or 5,000 SCF/bbl at 1.0 LHSV. V a r i a t i o n i n hydrogen flow r a t e i n oncethrough o p e r a t i o n has l i t t l e e f f e c t at more than 5,000 SCF/bbl. Operation at each c o n d i t i o n was f o r approximately 24 hours to allow 8-12 hours f o r e q u i l i b r a t i o n plus time to accumulate about 750 ml of l i q u i d product. Table I shows the sequence of r e a c t o r c o n d i t i o n s and e s s e n t i a l process r e s u l t s . P e r i o d 4 was a t e s t of a very m i l d c o n d i t i o n a f t e r a weekend shutdown. P e r i o d 7 was a t e s t of the l i q u i d feed pump at a low r a t e . P e r i o d 8 was a b r i e f t e s t f o r d e c l i n e i n a c t i v i t y from period 2, although the e n t i r e o p e r a t i o n was too short f o r s i g n i ficant l i f e testing. Periods i n the order of 2,1,3,5, and 6 were intended to cover the d e s i r e d range of i n c r e a s i n g upgrading. The l i q u i d feed and products were screened f o r chemical mutagens by use of the Ames assay ÇL, 40 . Results and D i s c u s s i o n The r e s u l t s i n Table I show the expected trends as hydrot r e a t i n g s e v e r i t y was increased w i t h r e a c t i o n temperatures i n the range of 310 to 400° C. S p e c i f i c g r a v i t y of the product l i quid at 375° C decreased from 1.00 f o r the feed to 0.89 w h i l e n i t r o g e n decreased from 1.06 wt-pct t o l e s s than .001 wt-pct and oxygen decreased from 3.29 wt-pct to 0.09 wt-pct. Hydrogen content increased from 8.42 wt-pct i n the l i q u i d feed to 12.24 wt-pct over t h i s same range of n i t r o g e n removal. C a l c u l a t e d hydrogen consumptions f o r t h i s range of c o n d i t i o n s v a r i e d from 970 to 2,880 SCF/bbl which i s w i t h i n the ranges reported by others (_2, 3). P r e c i s e hydrogen content of the l i q u i d product, used i n c a l c u l a t i o n of hydrogen consumption, was determined by NMR through the courtesy of P h i l l i p s Petroleum Company. A n a l y s i s of the e f f l u e n t gas d i d not i n c l u d e hydrocarbons h e a v i e r than ethane.
American Chemical Society Library 1155 16th St. N. W. Sullivan; Upgrading Coal Liquids Washington. 0. C. Society: 20036 ACS Symposium Series; American Chemical Washington, DC, 1981.
Sullivan; Upgrading Coal Liquids ACS Symposium Series; American Chemical Society: Washington, DC, 1981.
185
112
131
101
133
96
98
94
156
1
2
3
4
5
6
7
8
252
221
225
229
248
235
247
239
255
379
326
329
331
375
344
369
361
379
at wt-percent d i s t i l l e d 50 95
7
21
22
21
8
18
9
15
-
wt-pct converi 185°
Simulated D i s t i l l a t i o n of L i q u i d Feed and Products
Temp. , ° C , 5
(Feed)
Sample Period
TABLE I I .
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5.
SUTTERFIELD E T AL.
Hydrotreatment of SRC-II
149
Downloaded by PURDUE UNIV on July 6, 2016 | http://pubs.acs.org Publication Date: June 20, 1981 | doi: 10.1021/bk-1981-0156.ch005
C o n t r i b u t i o n s of the heavier hydrocarbons to hydrogen consumption are small f o r h y d r o t r e a t i n g at c o n d i t i o n s which cause very l i t t l e c r a c k i n g o f hydrocarbons s i n c e most o f the consumed hydrogen goes i n t o the l i q u i d product. The d i s t i l l a t i o n range of the l i q u i d products was s h i f t e d downward as h y d r o t r e a t i n g s e v e r i t y was increased (Table I I ) . The magnitude of the s h i f t o f the simulated d i s t i l l a t i o n i s shown i n the l a s t column which i n d i c a t e s 8 to 22 percent of the feed i s converted to m a t e r i a l b o i l i n g below the f i v e percent p o i n t o f the feed. The i n c r e a s e i n product m a t e r i a l b o i l i n g below 185 C r e s u l t s l a r g e l y from s a t u r a t i o n of aromatic r i n g s and o l e f i n s and from r e moval o f heteroatoms. Some hydrocarbons b o i l i n g lower than the feed would be formed by c l e a v i n g of heteroatom l i n k a g e s , with very l i t t l e cracking o f hydrocarbons expected. For example, a l l product l i q u i d s had i n i t i a l b o i l i n g p o i n t s c l o s e to that of benzene/ cyclohexane. The r e s u l t s o f the Salmonella/Typhimurium Mutagenicity (Ames) assay f o r the feed and l i q u i d products are given i n Table I I I . The assay was run e s s e n t i a l l y as described by Ames (_1) . The assay employs s p e c i a l l y constructed s t r a i n s of Salmonella Typhimurium which are r e v e r t e d by a wide v a r i e t y of mutagens from r e q u i r i n g h i s t i d i n e i n t h e i r growth media back to b a c t e r i a capable of synthesizing histidine. Some chemicals r e q u i r e metabolic a c t i v a t i o n ( a d d i t i o n of microsomal enzymes) p r i o r to showing mutagenic a c t i v i t y ; thus, data are given as number of r e v e r t a n t s without/with metabolic activation. The Ames t e s t has thus f a r demonstrated a strong c o r r e l a t i o n between p o s i t i v e carcinogenesis i n animal t e s t s and mutagenicity i n the Ames t e s t ÇL, 4·). However, p o s i t i v e r e s u l t s from the Ames t e s t do not c o n c l u s i v e l y show human r i s k . The untreated SRC-II was t e s t e d a t f i v e concentrations with Salmonella s t r a i n s TA 98 and TA 100, g e n e r a l l y considered the most sensitive strains. In the r e s u l t s i n d i c a t e d i n Table I I I , an i n crease i n the number of r e v e r t a n t s greater than two times the background (no SRC-II feed o r product) i s sometimes considered to i n d i c a t e a d e f i n i t e p o s i t i v e (mutagenic) response. The p l a t e s which showed a p o s i t i v e response by t h i s c r i t e r i a are u n d e r l i n e d . A c t i v i t y decreased with decreasing c o n c e n t r a t i o n f o r the unt r e a t e d feed but was s t i l l n e a r l y double the a c t i v i t y of the background a t a c o n c e n t r a t i o n of 5 ug per p l a t e . A product dose of one hundred micrograms was s e l e c t e d as a s a t i s f a c t o r y screening t e s t s i n c e a strong response was observed f o r the untreated SRC-II at t h i s c o n c e n t r a t i o n and s i n c e no a p p r e c i a b l e c y t o t o x i c i t y was noted. The hydrogénation periods are l i s t e d i n order of i n c r e a s ing s e v e r i t y o f p r o c e s s i n g . A c t i v i t y was decreased e s s e n t i a l l y to the background l e v e l when n i t r o g e n content was decreased to 0.35 wt-pct, oxygen content was decreased to 0.59 wt-pct and hydrogen content was increased from 8.4 to 10.8 wt-pct. T h i s occurred at
Sullivan; Upgrading Coal Liquids ACS Symposium Series; American Chemical Society: Washington, DC, 1981.
UPGRADING COAL LIQUIDS CM
00 vO
