Process for improving thermal stability of synthetic lubes

Abstract

A process is disclosed for improving the thermal stability of polyalpha-olefin lubricants by contacting the lubricant with an acidic catalyst for a time and at a temperature sufficient to achieve the skeletal isomerization of the molecular structure of the lubricant. The reaction is carried out preferably on unhydrogenated synthetic lubricants in contact with Lewis acid catalysts. Following the isomerization reaction, the unsaturated lubricant is hydrogenated to produce lubricant with better thermal stability. Surprisingly, when the isomerization reaction is carried out using unsaturated oligomer produced from the oligomerization of alpha-olefins in contact with reduced Group VIB metal oxide catalyst on porous support as starting material the viscometric properties of the lubricant, e.g., viscosity and VI, are not significantly altered, although the thermal stability of the lubricant is substantially increased. The reaction of the present invention may be carried out in the presence of a solvent or neat. Improvements in thermal stability are observed over a wide range of catalyst concentration. Concentrations of about 10 weight percent are preferred with aluminum chloride catalyst.

Dependencies are inferred from the claim text.