GB428936A - A process for improving synthetic lubricating oils - Google Patents

Abstract

Synthetic lubricating - oils obtained as described below are improved by extraction with selective solvents, e.g. nitrobenzene, aniline, acetonitrile, benzonitrile, chlorinated ethers, esters of aliphatic alcohols liquid sulphur dioxide, liquefied propane or other normally gaseous aliphatic hydrocarbon or mixtures. Agents lowering the setting point may be added to the treated oils. The synthetic oils are those made by polymerization or condensation of the liquid olefines produced by cracking paraffin wax or fats or fatty oils, or by dehydrating alcohols obtained by hydrogenation of fats or fatty oils; the olefines may be mixed with mineral or tar oil fractions, or cracking or destructive hydrogenation products of coals, tars, or mineral oils; and high molecular condensation products of isobutylene may be added before, during, or after condensation. The extraction is effected by mixing and setting, or by countercurrent flow, suitably at -30 DEG C. to 50 DEG C. and if desired at increased pressure. When the temperature is sufficiently low any contained paraffin wax separates from the oil and may be removed to improve the setting point. For example, a lubricating oil obtained by the aluminium chloride condensation of a mixture of a cracking product of paraffin wax with German petroleum is treated with an equal weight of 2,2<1>-dichlorethyl ether; the viscosity index is raised from 104 to 115.