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 gamma-alumina catalysts currently u sed deactivate rapidly during coal liquids hydroprocessing, the feasib ility of removing the more intractable material from a typical coal ex tract solution prepared with hydrogenated anthracene oil (HAO) was exa mined 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-insol uble concentrations for the modified extract solutions. As the amount of toluene added to approximately 1 kg of the coal/HAO digest was redu ced below 300 cm(3), the ash contents of the resultant filtered extrac t solutions increased toward the normal concentration of ca. 0.03% obt ained without precipitation. Batchwise and continuous hydroprocessing tests conducted on the normal and modified coal extract solutions with a commercial Ni/Mo gamma-alumina-supported catalyst demonstrated that the lower concentrations of THF insolubles gave rise to significant i mprovements in conversion for the n-hexane, toluene, and THF insoluble s in the feeds. In accord with their higher surface areas and lower ca rbon contents, the HDS activities of catalyst samples recovered from a continuous run with feed modified by toluene addition were considerab ly higher than those for the corresponding samples for the normal feed .