GB566413A - Improvements in or relating to the production of high quality lubricating oils - Google Patents

Abstract

566,413. Purifying and de-waxing mineral oils. AKTIEBOLAGET SEPARATOR-NOBEL. Nov. 13, 1942, No. 16088. Convention date, Nov. 26, 1941. [Class 91] In the production of high quality lubricating oils from lubricating oil fractions by the addition of a selective solvent thereto, cooling to de-waxing temperature, and then cooling the de-waxed oil solution to a lower temperature at which the paraffinic lubricating oil hydrocarbons are precipitated and separated in solid or semi-solid form, the process is effected in the presence of an aromatic or naphthenic fraction by returning a part of the extract solution containing the aromatics or naphthenics to the initial lubricating oil fraction. The wax separated in the first stage of the process may be de-oiled by washing with the solvent, the washing liquors being used as diluent for the initial material. After equilibrium is reached, an amount of extract solution is continuously withdrawn corresponding to the amount fed to the fresh oil. The solvent used in the dewaxing stage, the wash oil solution obtained in the de-waxing stage, and the extract solution obtained in the second stage are respectively preferably added stepwise at dropping temperature to the initial material. The wash oil solution may be added with the extract solution to the initial material. The de-waxing may also be effected at dropping temperatures. Only apart of the de-waxed oil may be subjected to the second stage of the process. The de-waxed paraffinic fraction forms a highquality lubricating oil and the withdrawn de-waxed aromatic or naphthenic fraction may be used as burning oil &c. after the solvent has been removed in each case. Usual selective solvents such as methylene chloride', dichlorethane, acetone, butanone and methyl propyl ketone or mixtures thereof may be used in the process.