SYNTHESIS OF TRANSITION-METAL ARSENIDES AND ARSENIC METAL SULFIDES AND THEIR ROLE IN THE DEARSENATION OF SHALE OILS

One of the chief problems in upgrading shale oil is the presence of in herent arsenic, which is known to poison downstream catalysis. Highly dispersed transition metal sulfides formed in situ from the decomposit ion of dithiocarbamate (DTC) complexes of transition metals show excel lent potential as dearsenation agents. We have studied the reaction of these sulfides with various arsenic compositions, and characterized t he metal arsenides and arsenic metal sulfides formed as well as the ea se of their formation. Thus, the reaction of bis(butyldithiocarbamato) Ni, (NiBuDTC), with model compounds was very facile and gave NiAs, NiA sS, and NiAs2-xSx. In general the effectiveness of the sulfides for de arsenation followed the sequence Ni > Mo much greater than Co, while i ron sulfides were totally ineffective. Based upon these results, tests where run in autoclaves (as well as a fixed-bed flow-through unit) wi th Ni BuDTC and shale oil having 73 ppm inherent As. Under optimum con ditions, dearsenation down to less than 1 ppm was obtained. (C) 1994 A cademic Press, Inc.