A process for dewaxing is described. It includes the steps of mixing a waxy feedstock near its pour point with an ambient or below ambient temperature solvent essentially free of a selected cosolvent, to form a solvent/feedstock mixture, and subsequently adding the cosolvent to the solvent/feedstock mixture to cause instantaneous precipitation of wax on addition of cosolvent. The amount of wax precipitation is controlled by the quantity and temperature of the cosolvent added. The cosolvent is essentially completely miscible with the solvent, but immiscible with the oil and wax. For example, alcohols (methanol, ethanol, propanol), ketones (ketene, acetone), amines, etc. The process of the present invention provides the advantages of lower solvent ratios (higher solvent recovery), higher filtration temperatures, “environmentally compatible” solvents, rapid filtration rates, and debottlenecking of existing dewaxing plants.
University of Arkansas (Little Rock, AR) Advanced Refining Technologies, Inc. (Lakewood, CO)
Ackerson, Michael D.; Arabshahi, Seyed-Hamid; and Babcock, Robert E., "Petroleum-wax separation" (1998). Patents Granted. 198.