Refining highly aromatic lube oil stocks

摘要

A process for solvent extraction of higher aromatic hydrocarbon oils with N-methyl-2-pyrrolidone wherein N-methyl-2-pyrrolidone is separated from a solvent-extract mix in a series of distillation steps with recirculation of a portion of a partially stripped extract mix from an intermediate distillation step to the extraction step to improve the solvent-oil ratio in the extraction step and conserve energy as compared with conventional processes in which the solvent power of N-methyl-2-pyrrolidone is moderated by incorporating water in the solvent.