GB748154A - Improved process for the production of high quality lubricating oils - Google Patents

Abstract

Lubricating oil is obtained by distilling a crude petroleum oil to yield at least two fractions boiling in the range 650-1200 DEG F., solvent extracting these fractions separately to remove aromatic constituents, and/or constituents containing sulphur, oxygen or nitrogen, freeing the raffinates of solvent, hydrofining each of the raffinates in the presence of a hydrofining catalyst under conditions whereby the consumption of hydrogen during the hydrofining operation does not exceed 200 cu. ft./barrel of raffinate feed, measured at 60 DEG C. and 30 ins. Hg., and then removing entrained hydrogen, hydrogen sulphide and ammonia from the hydrofined oil by passing in contact therewith a gas which is inert towards the hydrofined oil. If necessary, the raffinates from the solvent extractions may be dewaxed before being subjected to hydrofining. Suitable solvents for use in the solvent extractions are phenols, furfural, liquid sulphur dioxide, nitrobenzene, aniline, cresols, chlorex, dimethyl formamide, dipropionitrile, liquid ammonia and amines. These solvents may be used in conjunction with solventmodifying agents such as water, alcohols and esters. The removal of wax from the raffinates may be accomplished by diluting the oil with a solvent such as liquid propane, chilling, filtering and then distilling solvent from the wax-free oil. Suitable catalysts for use in the hydrofining operation are nickel or kieselguhr, molybdenum oxide or sulphide or alumina, cobalt molybdate or alumina, platinum or alumina, or a blend of nickel sulphide and tungsten sulphide. The hydrogen may be supplied to the hydrofining operation as dilute hydrogen from a hydroformer or from the dehydrogenation of butylenes to butadiene. Preferred hydrofining conditions are a temperature of about 300-700 DEG F., a pressure of about 50-150 lbs./sq. in., a hydrogen recycle rate not exceeding 1000 cu. ft./barrel and a feed rate of about 0.5-10 v/v/hr. The hydrofined raffinates may finally be brought to the original flash point of the oil and passed down a packed tower countercurrent to a flow of oxygenfree steam, nitrogen or other inert gas. Apparatus for carrying out the process of the invention is described. Specification 737,020 is referred to.