PROCESS FOR IMPROVING THERMAL STABILITY OF SYNTHETIC LUBES

• Main Authors: SUZZY CHEN HSI HO, MARGARET MAY-SOM WU
• Format: Patent
• Language: English
• Published: 14.03.1991
• Edition: 5
• Subjects: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; CRACKING HYDROCARBON OILS; FUELS; INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATINGCOMPOSITIONS; LUBRICANTS; LUBRICATING COMPOSITIONS; METALLURGY; MINERAL WAXES; PEAT; PERFORMING OPERATIONS; PETROLEUM, GAS OR COKE INDUSTRIES; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVEHYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, ORGASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; TECHNICAL GASES CONTAINING CARBON MONOXIDE; THEIR RELEVANT APPARATUS; TRANSPORTING; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATINGINGREDIENTS IN A LUBRICATING COMPOSITION

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 neat or in the presence of a solvent. Improvements in thermal stability are observed over a wide range of catalyst concentrations. Concentrations of about 10 weight percent are preferred with aluminum chloride catalyst.