Removal of small amounts of high melting components (waxes) that cloud the oil at storage temperature. The term is typically associated with processing of sunflower and rice bran oils. The oil is chilled then mixed with filter aid. After holding the oil for a certain period, the waxes become solid (crystallize) and can be removed by filtration. In some cases centrifugal separation is used in combination with degumming, neutralizing or water washing instead of filtration.
the separation process used to refine waxy gas oils into wax-free oil. Solvent dewaxing, in which a mixture of feed and solvent is chilled to crystallize the waxy portion for removal by filter or centrifuge, produces low-pour lube base stocks and slack wax. The slack wax may be deoiled to reduce oil content and produce fully-refined wax. Alternate technologies for dewaxing include wax hydroisomerization, in which wax molecules are branched in a catalytic reaction and converted into high VI lubricants, and catalytic dewaxing, in which wax molecules are destroyed and become lighter, fuels products.