SEPARATION OF DEWAXING SOLVENT FROM DEWAXED OIL IN A LUBE OIL DEWAXING PROCESS USING ASYMMETRIC POLYIMIDE MEMBRANES

摘要

ABSTRACT OF THE DISCLOSUREDewaxing solvents, particularly ketone sol-vents, and ketone/toluene solvents are separated from amixture of dewaxing solvents and dewaxed oil in a lubeoil dewaxing process by use of a permselectiveasymmetric polyimide membrane. Said asymmetric polyi-mide membrane permits the selective permeation of theketone or ketone/toluene dewaxing solvent while beingless permeable to oil. Said separation is conducted bycontacting the ketone or ketone/toluene solvent/oilmixture with the dense side of the asymmetric polyimidemembrane under pressure. The recovered ketone orketone/toluene solvent is of high enough purity to bereturned to the dewaxing process without further treat-ment. The recovered oil is passed to subsequent conven-tional treatment means (e.g., distillation) for removalof any ketone or ketone/toluene solvent remainingtherein.