GB911813A - Process for the catalytic hydrogenative refining of hydrocarbon wax - Google Patents

Abstract

Hydrocarbon waxes from high boiling hydrocarbon mixtures, including those obtained by de-waxing lubricating oils, are catalytically hydrofined by contacting the wax in the presence of a hydrogen-containing gas with a tungstennickel sulphide catalyst at a temperature not above 360 DEG C., preferably at 250 DEG -300 DEG C. for distillate waxes and 300 DEG -350 DEG C. for residue waxes and at a pressure above 40 atmos. abs. and preferably above 80 atmos. abs., the atomic ratio W:Ni in the catalyst being 3:1 to 1:3, and most suitably about 2:1. The catalyst may also contain iron sulphide, the amount of which is less than 25%, and preferably less than 10% by weight of the catalyst (both calculated as metal). The wax to be treated most suitably contains less than 5% by weight of oil and is most conveniently treated in the trickle phase, being passed over the catalyst bed at a liquid hourly space velocity of 0,5-5, preferably 0,7-2, kg./hr./litre of catalyst and at a gas:wax ratio of 100-1000, preferably 200-500, litres (S.T.P.)/kg. wax; the gases used should contain more than 60%, and most suitably more than 85%, by volume of hydrogen. The catalyst is most conveniently used when supported on a carrier such as active carbon, fuller's earth, kieselguhr, pumice, bauxite, burnt clay or, preferably, alumina; the weight ratio of the catalyst to such a carrier is suitably 1:4 to 2:3. The carrier is impregnated with a solution of a mixture of salts of tungsten, nickel and, if required, iron to form a paste, the resultant material is dried, pelletted with stearic acid, the stearic acid burnt off in the presence of oxygen, the product calcined at 500 DEG C. to the oxides, reduced with hydrogen to the metals, and finally sulphided by treatment with hydrogen sulphide or other sulphur compounds, with or without hydrogen, at 10 atoms, abs. and 100 DEG C. rising gradually if desired to 250 DEG -450 DEG C. Iron-containing catalysts may be obtained without separate addition of iron by using a ferriferous carrier. Alternatively the catalyst may be produced unsupported (1) by treating a suitable mixture of the metals, the oxides or the hydroxides with hydrogen sulphide, sulphur, carbon disulphide or another sulphur compound, or (2) by producing the sulphides separately and then mixing in the ratio required. Specification 657,521 is referred to.