Energy & Fuels 1989, 3, 148-153
148
Effect of Coal and Residuum on Reactions Occurring in Coal-Petroleum Processing+ Christine W. Curtis* and Wook Jin Chung Chemical Engineering Department, Auburn University, Auburn, Alabama 36849 Received August 4, 1988. Revised Manuscript Received December 12, 1988
The interactive chemistry occurring between coal and petroleum species present during coprocessing has been investigated by reacting, under thermal and catalytic conditions, model systems that were composed of compounds representative of coal and petroleum residuum. Then, coal and residuum were individually introduced into the model systems and reacted. Under the reaction conditions of 350 OC and 1250 psig H2charged at ambient temperature, the amount of hydrogenation and heteroatom removal of the individual reactants as well as the influence of reactant combinations on the reactions occurring was determined. The model systems used individually and in combination were naphthalene, 1,4-dimethylcyclohexane,phenol, benzothiophene, and quinoline. Under thermal conditions, the presence of several reactants had little influence on the products produced compared to the individual reactant case. However, with a catalyst, quinoline substantially decreased hydrogenation of naphthalene, with phenol and benzothiophene showing lesser effects. In several reactant systems, the presence of naphthalene and dimethylcyclohexane seemed to have a positive effect on heteroatom removal. Illinois No. 6 coal and Maya TLR residuum, individually added to the model catalytic reactions, decreased both hydrogenation and heteroatom removal, with Maya TLR being the most detrimental.
Introduction The coprocessing of coal with petroleum residuum simultaneously liquefies coal and upgrades the coal liquids and petroleum residuum into higher value products. Coal and petroleum residua are both fossil fuel resources but are considered to be derived from different geological origins.' Although they contain many of the same chemical species, they manifest very different physical and chemical properties with coal being a solid containing more aromatic species with a H/C atomic ratio of 0.6-0.8 and petroleum residuum being tarlike and containing more saturated species with a H/C ratio of 1.4-1.6.In coprocessing, these chemically different, complex materials are combined and reacted. A number of studies have examined the feasibility of coprocessing on the basis of product selectivity and reduction in metals content of the However, the mechanisms of coprocessing and the chemical interactions among the coal-derived and petroleum-derived species during thermal and catalytic coprocessing have not yet been determined. Since the purpose of the residuum in coprocessing is to serve as a liquid slurrying solvent medium, in essence, replacing the coal recycle solvent in direct coal liquefaction, questions arise as to the reactivity of the residuum with coal and its liquefied products during coprocessing. The objective of this investigation was to examine the chemical interactions among components that are derived primarily from coal and those primarily from residuum during coprocessing. In this study, the reactions between coal- and petroleum-derived molecules that may be occurring in coprocessing have been evaluated by reacting model compound types representative of coal and petroleum individually and in combination at coprocessing conditions. These model systems were then combined individually
* Author to whom correspondence
should be addressed. Presented at the Symposium on Coal-Derived FuelsCoprocessing, 195th National Meeting of the American Chemical Society and 3rd Chemical Congress of North America, Toronto, Ontario, Canada, June 5-10, 1988.
with Illinois No. 6 coal and with Maya Topped Long residuum (TLR) and reacted under thermal and catalytic conditions. The model systems were composed of naphthalene, representing aromatics primarily from coal; 1,4dimethylcyclohexane, representing saturated alicyclics primarily from residuum; phenol, representing phenolics primarily from coal; benzothiophene, representing sulfur compounds from both coal and residuum; and quinoline, representing organic nitrogen compounds primarily from coal. Experimental Section Materials. The model compounds, naphthalene (99.998%) and benzene (99%),used in this study were obtained from Fisher, hexadecane (99%),tetralin (99%), phenol (99%),benzothiophene (97 % ), quinoline (99% ), 1,4-dimethylcyclohexane (99 % ), 1,2,3,4-tetrahydroquinoline(99% ), decalin (99% ), cyclohexane (99%), ethylbenzene (99%),ethylcyclohexane (99%), propylbenzene (98%), o-propylaniline(97%), and p-xylene (99%) were obtained from Aldrich, and propylcyclohexane (97%) and decahydroquinoline were obtained from Alfa Products. Maya TLR was supplied by Cities Service Research and Development Co. and Illinois No. 6 coal by Southern Co. Services. Analyses for Maya TLR and Illinois No. 6 coal are given in Table I. Shell 324 NiMo/Al,O, 1/92-in.extrudates with 13.2% Mo and 2.7% Ni were used in catalytic reactions. The catalyst was (1)Berkowitz, N. An Introduction to Coal Technology; Academic Press, New York, 1979. (2)Monnier, J. CANMET Rep. 1984, No. 84-5E. (3) Moschopedis, S. E.; Hawkins, R. W.; Fryer, J. F.; Speight, J. G. Fuel 1980, 59,647. (4)Moschopedis, S. E.;Hawkins, R. W.; Speight, J. G. Fuel Process. Technol. 1982,5, 213. (5)Rosenthal, J. W.;Dahlberg, A. J. U.S.Patent No. 4,330,393,1982. (6)Curtis, C. W.;Pass, M. C.; Guin, J. A.; Tsai, K. J. Fuel Sci. and Technol. Int. 1987,5, 245. (7) Curtis, C. W.; Tsai, K. J.; Guin, J. A. Ind. Eng. Chem. Process Des. Deu. 1985, 24 1259. (8)Curtis, C. W.; Tsai, K. J.; Guin, J. A. Ind. Eng. Chem. Res. 1987,
26. ~. , 12.
(9) Gatsis, J. G. Prepr. Pap.-Am. Chem. Soc., Diu. Fuel Chem. 1986, 3 I ( 4 ) , 181.
0887-0624/89/2503-Ol48$01.50/00 1989 American Chemical Society
Energy & Fuels, Vol. 3, No. 2, 1989 149
Coal-Petroleum Processing Table I. Analyses of Illinois No. 6 Coal and Maya TLR Illinois No. 6 Coal Proximate Analysis (wt % ) volatile matter fixed carbon ash moisture
35.8 50.9 10.3 3.0
Ultimate Analysis (wt %) carbon hydrogen nitrogen sulfur chlorine ash oxygen (by difference) H/C atomic ratio dry heating value, Btu/lb
Maya Topped Long Resid Elemental Analysis (wt % ) carbon hydrogen nitrogen sulfur oxygen (by difference)
68.4 4.4 1.4 3.2 0.1 10.6 11.9 0.78 12,800
85.3 10.8 0.5 4.2 1.5
Chemical and Physical Properties ash, w t % 0.08 aromaticity 0.37 refractive index at 20 "C 1.56 viscosity (40 "C), P 317 specific gravity 1.000 "API 10.0 Conradson carbon residue 15.9
Product Distribution (wt % ) oil 79.5 asphaltenes 20.5 preasphaltenes 0.0 presulfided in a flowing stream of 10 wt % H2S in H2, which was heated stepwise from 204 to 372 "C over a time period of 5 h. The catalyst was cooled and stored in a desiccator until used. Equipment. Both model residuum and coal reactions were performed in 12.3 cm3stainless-steeltubing bomb microreactors, which were vertically mounted on an agitator shaft and agitated at a rate of 850 cpm. The reactor was equipped with a Nupro fine metering valve for introduction of hydrogen. Model Reactions. The model systems, naphthalene, dimethylcyclohexane, phenol, benzothiophene, and quinoline, were reacted thermally and catalytically as 2 wt % reactants in hexadecane at 350 "C with 1250 psi of H2 charged at ambient temperature for 30 min. The total liquid charge was 3 g. For the catalytic reactions, 0.25 g of presulfided '/32-in. NiMo/A1203 extrudates were used. A Varian Model 3700 FID gas chromatograph equipped with a 30-m DB-5 fused silica column was used for analyzing the products from the model reactions with p-xylene as the intemal standard. Product identification was achieved by comparison of retention times with authentic compounds and by GC/MS analysis. Coal and Residuum Reactions. Illinois No. 6 coal (-150 mesh) and Maya TLR were added at 10 wt % each to the model reaction systems and were reacted under the same thermal and catalytic reaction conditions described above. When residuum was reacted with the model systems, insoluble matter (IM) was produced during the reaction. The IM was recovered by precipitating it from the product mixture, centrifuging, and then decanting the liquid product mixture. Results and Discussion The model reaction systems composed of naphthalene (NAPH), 1,4-dimethylcyclohexane (DMC), phenol (PN), benzothiophene (BZT), and quinoline (QN) were reacted individually and then combined together to ascertain the influence of the different components on the thermal and catalytic reactions of the different model systems. The model reaction systems were built in the following manner:
NAPH; NAPH and DMC; NAPH, DMC, and PN; NAPH, DMC, and BZT; NAPH, DMC, and QN. Then Maya TLR and Illinois No. 6 coal were added individually to each of the model systems. Under thermal conditions, very little reaction was observed either with the individual reactants or with the combined systems. In the catalytic reactions, however, each model system produced a number of products. Several terms have been defined to assist in comparing the data. These terms are percent hydrogenation (HYD), percent hydrodeoxygenation (HDO), percent hydrodesulfurization (HDS), percent hydrodenitrogenation (HDN), and percent hydrogenolysis (HYG). Percent hydrogenation is the number of moles required to produce the observed product distribution from a given reactant as a percentage of the moles of H2 required to obtain the most hydrogenated product. Percent hydrodeoxygenation is the summation of the mole percents of components not containing oxygen. Percent hydrodesulfurization is the summation of the mole percent of components not containing sulfur. Percent hydrodenitrogenation is the summation of the components not containing nitrogen. Percent hydrogenolysis is the summation of the mole percents of the components that have undergone cleavage of the carbon-heteroatom bond. Thermal Reactions of Model Systems. Thermal hydrotreatment of the model reactants yielded little reaction, regardless of whether the reaction was performed with the individual reactant alone or in combination with other reactants. Less than 0.2% hydrogenation of NAPH occurred thermally at 350 OC. The addition of P N or BZT to the NAPH and DMC system did not affect the conversion of NAPH or the distribution of the DMC isomers. The only model reactant that thermally hydrogenated at 350 "C was QN. When reacted alon'e, 13% of QN was converted to THQ; however, when QN was added to NAPH and DMC, the amount of HYD was reduced and only 6% of QN was converted to THQ; NAPH and DMC remained unaffected. The addition of coal or residuum to the thermal reaction systems only affected the conversion of QN. With coal, QN remained unconverted and 80% of the QN was recovered. The addition of Maya TLR also eliminated the thermal hydrogenation of QN, but a higher recovery of 90% was achieved. By contrast, in the absence of coal, 13% conversion of QN to THQ occurred and more than 90% of QN and its products was recovered. The effect of coal or residuum was to block the intermediate hydrogenation pathway from QN to THQ even though excess hydrogen was present in the system. In the quaternary NAPH/DMC/QN/coal system, no reactions occurred and a recovery of 75% QN was achieved. The DMC isomer distribution was substantially changed in the presence of coal giving a trans to cis ratio of 51:49 compared to a 4456 ratio in the original DMC and DMC reacted with NAPH. In the NAPH/DMC/QN/Maya TLR systems, the thermal hydrogenation of QN was also inhibited and the isomer distribution for trans- to cis-decalin was changed to 5050. In the thermal reactions of coal at 10 wt % in hexadecane, negligible hydrogen consumption was observed; however, in catalytic hydrogenations slightly more than 16% of the initial hydrogen charged to the reactor was consumed during the reaction. Likewise, in the thermal reactions of Maya TLR, 1.7% of the hydrogen was consumed, while the catalytic reaction increased that to more than 5%. In the thermal residuum reaction, -8% IM was produced from the residuum regardless of the model system used. However, under catalytic conditions the IM
Curtis and Chung
150 Energy & Fuels, Vol. 3, No. 2, 1989 Naphthalene Hydrogenation
Naphthalene
Telralin
cis and trans
- Decalin
Phenol Hydrodeoxygenation ?H
Phenol
Benzene
Cyclohexane
Benzothiophene Hydrodesulfurization
0 S 1-0 Benzolhiophene
S
L
2,3-Dihydrobenzolhiophene
a c H @cH2cH3 2 c H 3H h CH2CHj
O
H2S
SH
Elhylthiophenol
Elhylbenzene
Elhylcyciohexane
Figure 1. Reaction pathways for the hydrogenation of naphthalene, the hydrodeoxygenation of phenol, and the hydrodesulfurization
of benzothiophene.
Table 11. Effect of Different Systems on the Catalytic Hydrogenation of Naphthalene" systems hydrogenation, % 94.7 f 0.4 naphthalene 94.8 f 0.8 naphthalene/DMC naphthalene/DMC/phenol 89.0 f 1.1 75.9 f 1.9 naphthalene/DMC/ benzothiophene 32.5 f 1.8 naphthalene/DMC/quinoline 57.8 f 0.2 naphthalene/coal 39.4 f 2.1 naphthalene/resid 57.0 f 0.2 naphthalene/DMC/coal
naphthalene/DMC/resid naphthalene/DMC/phenol/coal naphthalene/DMC/phenol/resid naphthalene/DMC/benzothiophene/coal
naphthalene/DMC/ benzothiophene/resid
naphthalene/ DMC/quinoline/coal naphthalene/DMC/quinoline/resid
36.1 54.3 36.4 50.6 32.1 17.9 16.3
systems phenol
phenol/DMC/naphthalene phenol/coal phenol/resid phenol/DMC/naphthalene/coal phenol/DMC/naphthalene/resid
hydrogenation, % 100 100 100 82.0 f 2.7 100 88.9 f 3.8
deoxygenation, % 100 100 100 82.0 f 2.7 100 88.9 f 3.8
f 1.6 f 1.7 f 2.3
a Reaction conditions: 350 O C , 30 min, 2 w t % of model reactant and 10 wt % of actual reactant in hexadecane, and 1250 psig of H2charged at ambient temperature.
= 3.7 = 0.1
the NAPH/DMC system reduced the percent HYD to 89% yielding, from NAPH, 18% T E T and the remainder product as DEC whose isomer distribution was the same as that for the individual NAPH reaction. The addition of BZT to NAPH/DMC reduced the percent NAPH HYD more to 75.9% yielding nearly 40% of the NAPH product as TET. The presence of BZT had a small effect on the DEC isomer distribution produced, giving 73.5% trans and 26.1% cis. QN had the greatest effect on NAPH HYD of any of the heteroatom-containing species. QN reduced the percent NAPH HYD to 32.5% and prevented total conversion of NAPH to hydrogenated products, leaving 22 % of NAPH unconverted and yielding T E T as the major product from NAPH. The amount of DEC produced was less than 3% with an isomer distribution of 73.1% transand 26.9% cis-DEC. Hydrodeoxygenation of Phenol. Phenol, whose reaction pathway is given in Figure 1, was selected to represent phenolic compounds present in coal. Although in the DB-5 fused-silica capillary column available for this work the two hydrogenation products, benzene (BZ) and cyclohexane (CH), could not be distinguished, a mass spectrum of the products achieved indicated that CH was the predominant product. Therefore, in quantifying the product distribution from PN, the BZ/CH mixture was assumed to consist only of CH. The catalytic hydrotreatment of P N resulted in total deoxygenation and conversion to CH as shown in Table 111. The addition of P N to the NAPH/DMC system somewhat inhibited NAPH HYD. NAPH was totally converted, producing 18% TET and 82% DEC and giving a NAPH HYD of 89% compared to 95% without PN. Hydrodesulfurization of Benzothiophene. The reaction pathway observed for BZT in the presence of the
= 0.6 f 0.2
"Reaction conditions: 350 O C , 30 min, 2 wt '70 of each model reactant and 10 wt % of each actual reactant in hexadecane, and 1250 psig of H2charged at ambient temperature.
-
Table 111. Effect of Different Systems on the Catalytic Reaction of Phenol" hydro-
produced was reduced to 5 70. Catalytic Reactions. Catalytic reactions were performed with presulfided Shell 324 NiMo/A1,03 by using both individual and combined model reactants systems. Since NAPH was the base reactant upon which all of the model systems were built, the influence of the reactants with heteroatomic components on catalytic NAPH hydrogenation was ascertained as was the effect of the hydrocarbons, NAPH and DMC, on heteroatom removal. In addition, the influence of coal and residuum on the hydrogenation and heteroatom removal of the model systems was examined. Naphthalene Hydrogenation. NAPH hydrogenation as shown in Figure 1 can be represented as a sequential and reversible hydrogenation to the tetrahydro form, tetralin (TET), and then to the fully saturated species, decalin (DEC). Decalin was present as two isomers, cis and trans. Significant HYD of NAPH of 94.7% occurred under catalytic conditions yielding DEC (91.2%) as the major product. The isomer distribution of the DEC produced under these conditions was 76.4% trans and 23.6% cis. Table I1 gives the percent HYD of NAPH in all of the systems. The addition of DMC did not change NAPH HYD. However, the addition of the heterocyclic compounds, PN, BZT, and QN, reduced the amount of catalytic NAPH HYD observed. The introduction of P N to
Coal-Petroleum Processing Table IV. Effect of Different Systems on the Catalytic Reactions of Benzothiophenea hydrohydrogena- desulfuriz- hydrogenosystems tion, % ation, % lysis, % benzothiophene 71.2 f 0.02 100 100 66.3 f 1.3 100 100 benzothiophene/DMC/ naphthalene benzothiophene/coal 56.3 f 0.1 100 100 benzothiophene/resid 48.6 f 0.2 96.2 f 0.2 96.2 f 0.2 benzothiophene/DMC/ 55.4 f 0.2 100 100 naphthalene/coal benzothiophene/DMC/ 51.6 f 0.5 100 100 naphthalene/resid "Reaction conditions: 350 "C, 30 min, 2 w t % of model reactant and 10 wt % of actual reactant in hexadecane, and 1250 psig of H2charged at ambient temperature.
Table V. Effect of Different Systems on the Catalytic Reactions of Quinoline" hydrodenitrohydrogen- genation, hydrogensystems ation, % % olysis, % quinoline 79.4 f 0.1 48.9 f 3.2 50.6 f 3.2 quinoline/DMC/naphthalene 79.9 f 0.9 54.6 f 3.8 56.6 f 4.4 61.0f 0.5 35.1 f 0.2 39.3 f 0.1 quinoline/coal quinoline/resid 60.6 f 0.5 34.7 f 0.9 42.5 f 0.6 quinoline/DMC/naphthalene/ 61.1 f 0.1 36.6 f 0.6 41.0 f 1.6 coal quinoline/DMC/naphthalene/ 62.8 f 0.2 38.0 f 1.3 47.0 f 0.4 resid "Reaction conditions: 350 OC, 30 min, 2 w t % for each model reactant and 10 wt % of actual reactant in hexadecane, and 1250 psig of H2 charged at ambient temperature.
NiMo/A120, catalyst is given in Figure 1.'O The first step in the reaction sequence was the saturation of the double bond in the five-membered ring forming dihydrobenzothiophene (DHBT). Then, the carbon-sulfur bond was cleaved, forming ethylthiophenol (ETP). Ethylbenzene (EBZ), produced through desulfurization of ETP, was further hydrogenated to ethylcyclohexane (ECH). Catalytic HDS of BZT produced two desulfurized products consisting of 58% EBZ and 42% ECH. Complete HDS of BZT occurred, and the HYD yield was 71% as presented in Table IV. When BZT was introduced to the catalytic hydrogenation of NAPH and DMC, and HYD's of both NAPH and BZT were decreased. NAPH was totally converted, yielding a NAPH HYD of 76% with the NAPH products being 40% TET and 60% DEC. BZT was totally desulfurized, yielding 66% HYD and forming 67% EBZ and 33% ECH. The DMC trans to cis ratio of 46:54 was slightly changed compared to the ratio of the unreacted DMC of 44:56. The presence of the released sulfur as H2S could conceivably affect the isomerization of DMC. Hydrodenitrogenation of Quinoline. The reaction pathway for quinoline reacted in the presence of NiMo/ A1203is presented in Figure 2.l' QN was hydrogenated at 350 "C to form 1,2,3,4-tetrahydroquinoline(THQ) and then was either further hydrogenated to decahydroquinoline (DHQ) or the carbon-nitrogen bond was cleaved, forming o-propylaniline (OPA). The principal final hydrogenation product formed was propylcyclohexane (PCH); a small amount of CH was also produced. The catalytic reaction of QN alone as given in Table V yielded a similar HYD to that obtained from the combined (10)Weisser, 0.; Landa, S. Sulphide Catalysts, Their Properties and Applications; Pergamon: New York, 1973. (11)Satterfield, C. N.;Yang, S. H. Ind. Eng. Chem. Process Des. Deu. 1984,23, 11.
Energy &Fuels, Vol. 3, No. 2, 1989 151 Table VI. Effect of Naphthalene, Tetralin, and DMC on the Catalytic Quinoline Reaction" hydrohydrogen- denitrogena- hydrogenation, % tion. % olvsis. % quinoline 79.4 i 0.1 48.9 f 3.2 50.6 f 3.2 quinoline/naphthalene 78.1 i0.7 47.5 i 1.7 49.1 f 1.7 quinoline/tetralin 78.2 i 0.8 50.1 f 0.04 52.1 f 0.4 77.6 i0.9 42.9 f 2.2 44.9 f 2.3 quinoline/DMC 77.9 i1.1 48.4 f 0.06 50.1 f 0.5 quinoline/tetralin/DMC ~
~~~~
OReaction conditions: 350 OC, 30 min, 2 wt % for each model reactant, and 1250 psig of Hzcharged at ambient temperature.
Table VII. Effect of Tetralin on the Catalytic TetrahydroquinolineReactiona hydrohydrogen- denitrogenahydrogenation, % tion, % olysis, % Individual Reactions tetralin 91.5 f 1.9 0 tetrahydroquinoline 71.5 f 1.7 44.3 f 0.8 45.8 i 0.2 tetralin tetrahydroquinoline
Combined Reactions 5.9 f 0.5 71.3 f 0.8 44.2 f 0.9
0 45.5 f 1.1
Reaction conditions: 350 OC, 30 min, 2 wt % for each model reactant, and 1250 psig of Hzcharged at ambient temperature.
reaction of NAPH, DMC, and QN. However, both the HDN and HYG of QN increased from 48.9 f 3.2% and 50.6 f 3.2% to 54.6 f 3.8% and 56.6 f 4.3%, respectively, upon the addition of NAPH and DMC to QN. The major products present were in the order of PCH > DHQ > THQ. Recovery of QN from the catalytic reactions was -68%, which was markedly less than the recovery achieved in the thermal reactions, indicating that QN or its reaction products were adsorbed on the catalyst surface and could not be recovered. Since the addition of NAPH and DMC to QN appeared to increase the HYG and HDN activity and since TET was the principal product from NAPH in the presence of QN, the influence of TET as an enhancing, hydrogen transfer agent on the HDN and HYG of QN was explored. As shown in Table VI, NAPH, TET, and DMC were individually combined with QN to compare their effects on HYD, HDN, and HYG. QN HYD was not substantially affected by any of these three compounds. However, DMC reduced both the HDN and HYG of QN compared to TET and NAPH. The DMC/QN system produced less PCH and more DHQ than the other binary systems while exhibiting a higher recovery, thereby indicating that the hydrogenolysis reaction pathway from DHQ to light products was inhibited. When T E T was added to the DMC/QN system (Table VI), TET did not have the same enhancing effect on HDN of QN as did NAPH. QN HDN in the binary systems of NAPH/QN and TET/QN was not as great as that occurring in the ternary NAPH/ DMC/QN system. Since the reaction pathway for QN HYD involved THQ as an important hydrogenated form, the combination of TET and THQ was reacted and their combined effect on the reaction products produced was explored. As an individual reactant T E T was completely hydrogenated to DEC, but in the presence of THQ that pathway was almost totally eliminated as shown in Table VII. This reduction in catalytic activity was most likely due to a poisoning of active hydrogenation catalytic sites by THQ. However, the addition of T E T to THQ did not affect the product slate produced from THQ. Hydrogenation of Model Systems with Coal. Although the results of the model compound systems are
Curtis and Chung
152 Energy &
I
U
(CHP)
(DHO)
1
(PCHA)
.C,H7
(PCH)
ON
-
CHP DHO OPA
- tetrohydraquinoline
- 2,3 - cyclohexenopyridine - decahydroquinoline (cis and - o-propylaniline
(MPCP)
PCHA - propylcyclohexylamine
quinoline
THO - I ,2,3,4
CH.
trans isomers)
- propylbenzene PCHE - propylcyclohexene (1,l or PCH - propylcyclohexane MPCP - mefhylpropylcyclopentane PB
1,3)
Figure 2. Reaction pathway for the hydrodenitrogenationof quinoline.
useful in elucidating the type of chemical interactions that occur between different petroleum and coal compounds, the real systems are more complicated and have chemical factors present that cannot be adequately represented by model systems. For this reason, Illinois No. 6 coal was introduced to the model systems to ascertain its effect on hydrogenation and heteroatom removal on the catalytic model reactions. Initial reactions with NAPH and coal were performed at two different weight percent levels of coal: 4.4 and 10%. At 4.4 w t % the amount of NAPH HYD w a ~72%,yielding 53% DEC; however, when the weight percent coal was increased to lo%,NAPH HYD decreased to -60% with more than 65% T E T being produced, thereby indicating that the quantity of coal present affected the amount of NAPH HYD inhibition obtained. For all other reactions performed with coal, the 10 wt % coal level was used, since the effect of the higher addition level on the model system reactions could more readily be observed. Reactions were then performed with coal and the individual reactants, DMC, PN, BZT, and QN, and then the heteroatomic reactants in combination with NAPH and DMC. For DMC, the presence of coal in the reactor had no effect on the DMC in either thermal or catalytic reactions. The catalytic reactions involving the combination of NAPH, DMC, and heteroatomic species with coal gave results very similar to those for each model compound/coal reaction as shown in Tables 111-V. The reactions of PN with coal were examined thermally and catalytically as given in Table 111. P N did not react thermally; however, a marked difference in the recovery of P N achieved from an individual reaction compared to the coal reaction was observed. In the individual thermal reaction, approximately 90% recovery was obtained but with coal only 30% of the P N was recovered. Thus, P N was either chemically or physically incorporated with the coal. In the catalytic reactions, P N was totally hydrodeoxygenated with coal as it was without, forming predominantly CH or BZ. The exact extent of P N conversion could not be determined as mentioned previously. More than 90% recovery of P N was obtained, indicating little or no incorporation of P N into the coal. The catalytic reaction of NAPH/DMC/PN with coal resulted in a small
reduction of NAPH HYD and in no change in the isomer distributions of DMC and DEC. The addition of coal to the catalytic HDS of BZT resulted in total desulfurization of BZT but only achieved 56% HYD of BZT compared 66% HYD without coal (Table IV). The presence of coal inhibited the hydrogenation pathway of EBZ to ECH, yielding from BZT 12.6%ECH with coal and 42.3% without coal. When coal was introduced to the NAPH/DMC/BZT system, NAPH HYD decreased to -51% compared to 54% with PN and 57% without any heteroatoms. Thus, BZT in conjunction with coal had a greater inhibiting effect on the conversion and HYD of NAPH than did PN. The product distribution of BZT for the NAPH/DMC/BZT/coal system was very similar to that of the BZT/coal without NAPH/DMC. The isomer distribution of DMC was somewhat altered just as it was without coal. The trans to cis ratio of DEC also changed from 7624 obtained from the NAPH/DMC/coal system to 73:27 obtained with the inclusion of BZT. As shown in the model reactions, the presence of sulfur with a catalyst appeared to cause changes in the isomer distribution of DMC and DEC. The catalytic reactions of QN with coal yielded a lower recovery of QN than the thermal reactions, reducing it from 80% in the thermal to 65% in the catalytic reactions. As shown in Table V, the catalytic reactions of QN with coal yielded 61% HYD, 35% HDN, and 39% HYG and gave the order of the primary products as THQ (42%) > PCH (32%)> DHQ (19%). These results are in contrast to the catalytic hydrogenation of QN without coal, which reversed the order, PCH (45%) > DHQ (40%) > THQ (9%),and yielded more of the other hydrogenated products. These results indicated that coal, perhaps through catalyst poisoning, inhibited the intermediate hydrogenation pathway from THQ to DHQ, the hydrogenolysis of DHQ, and the further hydrogenation to PCH. When NAPH and DMC were added to the QN/coal system, the catalytic HYD of QN was the same as the system without NAPH and DMC; however, the amount of HDN of QN was slightly increased by 1.5%with NAPH and DMC compared to that in their absence. The standard deviations achieved for these reactions were 0.6% or less. The NAPH/DMC/QN/coal system produced
Energy & Fuels, Vol. 3, No. 2, 1989 153
Coal-Petroleum Processing slightly less DHQ (16%) and slightly more PCH (33%) than the reaction without NAPH/DMC although the order of the major products was the same. These results suggest that the presence of NAPH/DMC slightly promoted the hydrogenolysis reaction pathway from DHQ to PCH. The isomer distribution of DMC was changed from a 44:56 trans to cis ratio without coal to 51:49 with coal as it was in the thermal reaction. Comparing the NAPH/DMC/coal system with QN to the system without QN showed a substantial inhibition of NAPH HYD, reducing it from 57 % without QN to 18% with QN. More than half of the NAPH remained unconverted, and no DEC was formed. Thus, although the presence of coal only had a minor effect on the reactions involving QN, coal in combination with QN substantially affected the HYD of the hydrocarbon species, NAPH. Hydrogenation of Model Systems with Residuum. Maya TLR was added to the thermal and catalytic model system reactions. The thermal reaction of Maya TLR with P N yielded a recovery of 90%, which was much higher than that from coal. Evidently the PN did not chemically or physically incorporate into the residuum. In the catalytic reaction of Maya TLR with NAPH, NAPH HYD was substantially reduced to 39% (Table 11), leaving 14% of the NAPH unconverted and yielding 78% T E T and 8% DEC. Addition of Maya TLR to NAPH/DMC resulted in reduction of NAPH HYD to 36% while the isomer distribution of DMC was changed to a 51:49 trans to cis ratio compared to 44:56 without Maya TLR. This change occurred with Maya TLR in both thermal and catalytic reactions and in the Maya TLR systems containing PN, BZT, and QN, which suggests that the change in isomer distributions resulted from the presence of the Maya TLR. When P N was reacted catalytically with Maya TLR, the recovery of P N was 91 % , which was similar to that obtained with coal. The presence of Maya TLR reduced the HDO of P N from 100% in the individual reaction to 82% (Table 111). Maya TLR was the only reactant of any of those used to inhibit the P N HDO. The presence of NAPH and DMC in the PN/Maya TLR system moderated the inhibition of Maya TLR on P N HDO, increasing it to 89%. In comparison with the individual catalytic reaction of BZT, the addition of Maya TLR decreased the BZT HYD and HDS to 49% and 96% from 72% and loo%, respectively (Table IV). As in the case of PN, Maya TLR had a stronger inhibiting effect on BZT than did coal. One possible explanation for this effect is that at 350 OC coal may not have been totally dissolved and available for interacting with the model species and catalyst while the residuum was readily available. The addition of NAPH and DMC to the BZT/Maya TLR system promoted the conversion of BZT as well as the HDS and HYD of BZT occurring in the presence of Maya TLR. The addition of Maya TLR to the catalytic reaction of QN resulted in decreasing the amount of HYD, HDN, and HYG compared to the individual reaction (Table V). The order of major products obtained with Maya TLR was THQ (41%) > PCH (32%) > DHQ (17%) while that obtained without Maya TLR was PCH (45%) > DHQ (40%) > THQ (9%). Thus, the presence of Maya TLR strongly inhibited the reaction pathway from THQ to DHQ. The addition of NAPH and DMC to the Maya TLR/QN sys-
-
tem appeared to have a promoting effect on HYG reactions and increased the amount of C-N bond cleavage observed. Summary and Conclusions Thermal hydrogenation reactions a t 350 OC, as performed in this work, did not lead to the hydrogenation of any of the model systems except for QN. Combinations of the model systems did not result in thermal chemical reactions among the species except in the case of QN where the addition of hydrocarbons reduced the amount of QN HYD. The addition of coal and residuum to QN totally eliminated the thermal HYD of QN. In the catalytic reactions, no effect on the HYD of NAPH was observed by the presence of DMC. However, the addition of NAPH and DMC to the reaction systems containing Maya TLR/PN, Maya TLR/BZT, and Maya TLR/QN showed a promoting effect on heteroatom (N, S, and 0) removal and HYD of BZT and QN under the catalytic conditions. In the systems with coal, the addition of NAPH and DMC promoted HDN and HYG of QN but did not affect the other reactions. In the QN reaction alone, the promoting effect by the presence of NAPH/ DMC on the HDN and HYG of QN was observed, but the HYD of QN was not affected. The only inhibitor of P N HYD and HDO was Maya TLR whose effect was moderated by the addition of NAPH and DMC. NAPH HYD was inhibited by the addition of all heteroatomic species as well as coal and residuum, with QN and Maya TLR being the most detrimental. Nomenclature BZ BZT CH CHP DEC DHBT DHQ DMC EBZ ECH ETP HDN HDO HDS HYD HYG IM MPCP NAPH OPA PB PN PCH PCHE QN TET THQ TLR
benzene benzothiophene cyclohexane 2,3-cyclohexenopyridine decalin dihydrobenzothiophene decahydroquinoline 1,4-dimethylcyclohexane ethylbenzene ethylcyclohexane ethylthiophenol hydrodenitrogenation hydrodeoxygenation hydrodesulfurization hydrogenation hydrogenolysis insoluble matter methylpropylcyclopentane naphthalene o-propylaniline propylbenzene phenol propylcyclohexane propylcyclohexene (1,l or 1,3) quino1ine tetralin 1,2,3,4-tetrahydroquinoline Topped Long residuum
Acknowledgment. We gratefully acknowledge the support of this work by the Department of Energy under Grant No. DEFG-2285PC80502. Registry No. NAPH, 91-20-3; DMC, 589-90-2; PN, 108-95-2; BZT,95-15-8;QN, 91-22-5; TET,119-64-2; THQ, 2544804-8;Ni, 7440-02-0; Mo, 7439-98-7.
