Effect of precipitating some of the more intractable material from a hydrogen-donor solvent coal extract solution on its hydroprocessing behavior

In view of the fact that the Ni/Mo ?-alumina catalysts currently used deactivate rapidly during coal liquids hydroprocessing, the feasibility of removing the more intractable material from a typical coal extract solution prepared with hydrogenated anthracene oil (HAO) was examined by precipitation with toluene both prior to and after filtration. The reductions in total conversion to pyridine solubles of only 3-4% achieved were accompanied by a decline of nearly 50% in the THF-insoluble concentrations for the modified extract solutions. As the amount of toluene added to approximately 1 kg of the coal/HAO digest was reduced below 300 cm³, the ash contents of the resultant filtered extract solutions increased toward the normal concentration of ca. 0.03% obtained without precipitation. Batchwise and continuous hydroprocessing tests conducted on the normal and modified coal extract solutions with a commercial Ni/Mo ?-alumina-supported catalyst demonstrated that the lower concentrations of THF insolubles gave rise to significant improvements in conversion for the n-hexane, toluene, and THF insolubles in the feeds. In accord with their higher surface areas and lower carbon contents, the HDS activities of catalyst samples recovered from a continuous run with feed modified by toluene addition were considerably higher than those for the corresponding samples for the normal feed.