(57) Slack waxes and synthetic wax (1) are isomerized and processed into high viscosity
index (VI) and very low pour point lube base stock oils and blending stocks (11) by
the process comprising the steps of optionally hydrotreating (3) the wax, if necessary,
to remove heteroatom and polynuclear aromatic compounds and/or optionally deoiling
the wax , if necessary, to an oil content between about 5-20% oil, isomerizing (5,
7) the wax over a catalyst of Group VI-Group VIII metal on a halogenated refractory
metal oxide support, said isomerization being conducted to a level of conversion
such that about 40% or less unconverted wax remains in the 330°C+ (preferably the
370°C+) fraction sent to the dewaxer. The total isomerate from the isomerization
unit is fractionated (8) into a lube oil fraction (9) boiling at 330°C+, preferably
370°C+. This oil fraction is solvent dewaxed (10), preferably using MEK/MIBK at 20/80
ratio, and unconverted wax (12) is recycled (12A, 12B) to the isomerization unit.
Operating in this manner permits one to obtain isomerate oil (11) of very high VI
(in excess of 130) possessing a low pour point (-21°C, preferably -24°C, most preferably
-27°C).
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