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Energy & Fuels 1989,3, 120-126
Coal/Oil Coprocessing Mechanism Studies+,$ Anthony V. Cugini* and Richard G. Lett Pittsburgh Energy Technology Center, U S . Department of Energy, P.O. Box 10940, Pittsburgh, Pennsylvania 15236
Irving Wender Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213 Received August 5, 1988. Revised Manuscript Received October 12, 1988
Initial coprocessing studies performed to provide a basis for studying mechanisms associated with the coprocessing of coal and residual oil are described. Areas investigated included the response of coal and petroleum resid combinations to processing under thermal hydrotreatment conditions, the means of increasing the conversion of coal, and the nature of resid demetalation effects. It was found that Maya ATB was superior to Boscan ATB or North Slope VTB for the conversion of Illinois No. 6 coal to liquid or soluble products. The extensive demetalation of the liquid product observed was a function of the amount of coal added. Results obtained by using different coal and resid combinations under thermal conditions and in the presence of various additives suggest that an adsorptive mechanism is operative. The primary interactions leading to demetalation appear to be between the metal complexes of the resid and the insoluble carbonaceous coal-derived material. Demetalation of the liquid product was not dependent on conversion of the organically complexed metal in the resids to inorganic form.
Introduction The rapid consumption of conventional light petroleum reserves and the increasing need to refine lower quality petroleum feedstocks have recently prompted serious consideration of technology for coprocessing coal with petroleum resids or heavy bitumens. Coprocessing is attractive as a possible route for introducing the processing of coal in an evolutionary manner into existing refinery infrastructures without immediately incurring the large capital investment associated with other coal liquefaction alternatives. A review of current coprocessing literature indicates a number of additional advantages may accrue from coprocessing coal and resid feedstocks.’ Among the potential benefits of adding coal during the upgrading of heavy petroleum oils or residua are (1)improved yields of liquid or distillate products, (2) inhibition of coke formation, and (3) enhanced demetalation of the liquid products. It is often claimed that coprocessing is superior to individual liquefaction of coal and upgrading of resid or bitumen feedstock^.^-^ Reference is occasionally made to a “synergism” during coprocessing, but the nature of this synergism is usually not well-defined. An experimental program was initiated a t PETC to obtain fundamental data on the coprocessing of coal with petroleum resids and to achieve a better understanding of the basis for observed “synergistic” interactions between coal and petroleum resid feedstocks. This work has focused on coprocessing of Illinois No. 6 bituminous coal and, to a lesser extent, Wyodak subbituminous coal with petroleum resids having widely different properties and cot Reference in this report to any specific commercial product, process, or service is to facilitate understanding and does not necessarily imply its endorsement or favoring by the United States Department of Energy. Presented a t 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.
*
0887-0624/89/2503-0120$01.50/0
Table I. Proximate and Ultimate Analyses of Feed Coals Wyodak Wyodak Illinois No. 6 (Burning Star) (Clovis Point) (Sarpy Creek) Proximate Analysis (wt %) (As Received) moisture 4.2 6.1 17.7 volatile matter 36.9 42.3 31.6 fixed carbon 48.2 40.8 38.8 10.7 10.8 11.9 ash Ultimate Analysis (wt % ) (Moisture Free) carbon 70.2 64.4 hydrogen 4.8 4.5 nitrogen 0.9 1.0 sulfur 3.1 0.9 oxygen 9.9 17.7 (difference) ash 11.1 11.5 sulfatic pyritic organic
62.9 3.9 0.8 0.9 17.0 14.5
Sulfur Forms (wt %) 0.03 0.02 1.2 0.2 1.9 0.7
processing characteristics. Areas that have been investigated are the response of different combinations of coal and resids to processing under thermal hydrotreatment conditions, the means of improving liquid product yields and coal conversions, and the extent and mechanism of liquid product demetaladon. Experimental Section Most of the coprocessing experiments were performed with Illinois No. 6 hvBb coal (-100-mesh) from the Burning Star Mine. A few comparative experiments were carried out with Wyodak ~~
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(1) Cugini, A. V. M.S. Thesis, Department of Chemical and Petroleum Engineering, University of Pittsburgh, August, 1985. (2) Shinn, J. H.; Dahlberg, A. J.; Kuehler, C. W.; Rosenthal, J. W.
EPRI Report A P 3825-SR EPRI: Palo Alto, CA, 1985. (3) Miller, R. L., EPRI Report AP-4345-SR EPRI: Palo Alto, CA, 1985. (4) Kelly, J. F.; Fouda, S. A.; Rahimi, P. M.; Ikura, M. Energy Laboratories, Division Report, DRP/ERL-84-52, September 1984. 0 1989 American Chemical Society
Energy & Fuels, Vol. 3, No. 2, 1989 121
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I
Table 11. ProDerties of Petroleum Resids North Maya Slope Boscan VTB (950 ATB (650 ATB (650 ultimate anal., wt. % carbon hydrogen oxygen nitrogen sulfur ash ppm of Ni ppm of V "API 850 O F vol %a heptane insolubles,b wt % M, (VPO, pyridine, 80 OC
H*, fa
OF+)
OF+)
OF+)
86.1 10.6 0.7 0.6 2.0
