Supercritical solvent extraction of direct liquefaction residue from Shenhua coal

Extraction of direct liquefaction residue from Shenhua coal with three solvents was investigated in a batch autoclave at supercritical conditions to clarify the impacts of pressure, temperature, and extraction time on the yields of heavy liquid and its compositions. It is found that when toluene is used as a solvent, extract time has no obvious effect on yield of heavy liquid, hexane soluble(HS) and asphaltene(A). Extract temperature, extract pressure and mass ratio of solvent to residue have significant effect on yield and composition of residue extract. During the supercritical solvent extraction of liquefaction residue, some other components are transformed into HS and this results in increasing yield of HS. Benzene shows similar extraction ability to toluene while ethanol is poor in dissolving heavy liquid. There are more light components in heavy liquid extracted by ethanol than those by benzene and toluene. Sulfur and ash are mainly enriched in extract residue during extraction process.