| abstract |
@ Dewaxing aids (8) used to improve the separability of wax from hydrocarbon oils (2), preferably petroleum oil, most preferably lube or transformer oils, are themselves recovered from the wax (16) and/or the dewaxed oil (24) by selective permeation of the wax (22) and/or dewaxed oil/ dewaxing solvent (28) through a semipermeable membrane (18 and/or 26) with the retained, recovered dewaxing aid (20 and/or 30) being recycled to the dewaxing process. The dewaxing aid (20 and/or 30) is recovered in an undegraded form, and is as effective in the dewaxing process as is fresh dewaxing aid. Degraded dewaxing aid, if any, passes through the membrane along with the wax (22) or oil or dewaxing solvent (28) and is thus not recovered for recycle. |