Multiple-stage hydrogen-donor coal liquefaction process

摘要

An increased yield of hydrogenated liquid product is obtained from coal by treating the feed coal with a hydrogen-donor solvent and hydrogen-containing gas in a first coal liquefaction reactor to produce a liquefaction effluent; separating the liquefaction effluent into a vaporous stream and a liquid stream, the liquid stream consisting of a low molecular weight liquid fraction and a high molecular weight liquid fraction; removing a sufficient amount of the low molecular weight liquid fraction from the high molecular weight liquid fraction to form a heavy bottoms stream containing less than about 50 weight percent of the low molecular weight liquid fraction based on the weight of the high molecular weight liquid fraction; treating the heavy bottoms stream with additional fresh hydrogen-donor solvent and hydrogen-containing gas in a second coal liquefaction reactor; separating the second liquefaction reactor product into a vaporous fraction and a liquid fraction, and recovering hydrogenated liquid products from the vaporous and liquid fractions. If desired the high molecular weight constituents in the liquid fraction from the second liquefaction reactor may be further treated with fresh hydrogen-donor solvent and hydrogen-containing gas in a third coal liquefaction reactor. Hydrogen-donor solvent may be preduced in the process by catalytically hydrogenating at least a portion of the liquid product from each liquefaction reactor, recovering a liquid fraction from the products of the catalytic hydrogenation, and separating a hydrogen-donor solvent from the liquid fraction.