Coal liquefaction process

Claim 1

A process for liquefying a particulate coal feed to produce useful petroleum-like liquid products, which comprises: (a) contacting, in a series of coal liquefaction zones, graded with respect to temperature such that the temperature ascends from the initial to the final zone of the series, an admixture of a polar compound selected from the group consisting the low molecular weight heterocyclic oxygen compounds containing from about 2 to about 6 fused rings, one or more of which is a five- or six-membered heterocyclic ring having from four to five carbon atoms in the nucleus and from one to two atoms of oxygen and the low molecular weight heterocyclic sulfur compounds containing from 2 to about 6 fused rings, one or more of which is a five- or six-membered heterocyclic ring having from four to five carbon atoms in the nucleus and from one to two atoms of sulfur a hydrogen donor solvent and particulate coal; the initial zone being maintained at a temperature between about 70° F. and 750° F. while providing a residence time ranging from about 20 minutes to about 150 minutes to disperse the coal, and the final zone being maintained at a temperature between about 750° F. and 950° F. while maintaining a residence time ranging from about 10 minutes to about 70 minutes, sufficient to hydroconvert and liquefy the coal, (b) separating the product from the coal liquefaction zone into fractions inclusive of a liquid solvent fraction with contains at least 30 weight percent hydrogen donor compounds, (c) hydrogenating said liquid solvent fraction in a hydrogenation zone, and (d) recycling the hydrogenated liquid solvent mixture to the initial zone of the series.