Performance indices for coal liquefaction solvents

Most coal liquefaction processes are based on the thermal cleavage of activated bonds giving reactive carbon and oxygen radicals which abstract hydrogen atoms from the donor solvent. The role of oil is approximated in this study by using a simple standard reaction. A series of five representative solvents react with phenyl and phenyloxy radicals generated by thermolysis of benzoyl peroxide at 87 °C in tetrachloroethylene. The n.m.r. analysis of the reacting mixture defines four performance indices, i.e. the hydrogen-donor, the efficiency, the recycle and the scavenger indices, which characterize the ability of these solvents as efficient recycle oils in coal liquefaction processes. 9,10-dihydrophenanthrene proves to be by far the most appropriate solvent for this purpose.