A residue from deasphalting a syncrude obtained by direct coal liquefaction of a subbituminous Spanish coal was processed by thermal hydrotreatment. Kinetic study of the cracking reaction and coke formation reaction has been performed. The viscosity, coke content, boiling point distribution, elemental analysis, and aromaticity of the reaction products have been determined. The experimental data fits with the first-order kinetic model proposed. The main effects observed with the thermal hydrotreatment have been a large decrease of the viscosity that varies from 4608 cSt in the feedstock to 147 cSt in the products. The conversion of the heavy fraction (bp > 350 °C and soluble in toluene) and asphaltenes increased with the temperature and residence time, and the formation of coke was inhibited even at the hardest reaction conditions used. At 425 °C a kinetic control conducts the reaction, the cracking reaction with lower activation energy was more favorable and the coke formation (condensation) remained almost completely inhibited.

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