Coal liquefaction solvents: An n.m.r. analysis of a recycle oil over successive passes

Abstract

Recycle distillates from a coal liquefaction continuous pilot plant, which used prehydrogenated anthracene oil as a start-up solvent and up to seven successive passes over an operation time of 800 h, were analysed by 13C and 1H n.m.r. to give average structure and molecular parameters. The fraction of donatable hydrogen steadily decreased in the successive recycle solvents, by ≈ 3 wt% over each pass, as a result of a slow degradation of benzonaphthenic rings into saturates and alkyl-substituted aromatics or five-membered hydroaromatics.