GB345738A - Improvements in the purification of mineral oils, tars, their distillation products and the like - Google Patents

Abstract

Mineral oils, tars, synthetic oils, and the like are refined by first removing, by polymerization, adsorption, or decomposition, those constituents which resinify or decompose when heated to 400 DEG C. in the presence of hydrogen, and then treating the resulting products with hydrogen at elevated temperatures in the presence of catalysts immune from poisoning by sulphur, if desired under pressure, so as to convert unsaturated compounds and compounds containing sulphur, oxygen, nitrogen, or halogens into hydrocarbons without substantial cracking. The removal of the injurious constituents in the first stage may be effected by stirring with dilute or weak acids such as 40 per cent sulphuric acid, or acetic, oxalic, or malonic acid; or by the addition of polymerizing catalysts such as sulphur, potassium hydrosulphide, zinc chloride, or aluminium chloride; or by heating in the liquid or vapour state under normal or elevated pressure with bleaching earth, silica gel, pumice, bauxite, and the like. In the latter treatment in the vapour state, gases such as hydrogen, water vapour, or air may be added. High boiling materials are preferably diluted with middle oils which are distilled off later. The second stage treatment with hydrogen is preferably carried out at 200-450 DEG C. with catalysts containing oxides or sulphides of the metals of groups 2-7, preferably in conjunction with metals of group 8 or with heavy metals of groups 1 and 2, or the oxides and sulphides thereof. The catalysts are preferably deposited on charcoal, Florida earth, silica gel and the like. In examples (1) benzol is passed with hydrogen over Florida earth at 250 DEG C., and then over nickel oxide and tungsten oxide on active carbon at 300 DEG C.; (2) solvent benzol of B.P. 140-200 DEG C. is passed with hydrogen at 200 atmospheres and 250 DEG C. through bleaching earth, and is then passed at the same pressure at 350 DEG C. over nickel sulphide and chromium oxide on fuller's earth; (3) a coal-tar middle oil of B.P. 120-350 DEG C. is washed with 40 per cent sulphuric acid, distilled, and treated in the liquid phase with hydrogen at 200 atmospheres and 350 DEG C. with a catalyst of cobalt and molybdenum sulphides, with or without zinc oxide, on Florida earth. Specifications 249,309, [Class 91, Oils &c.], 267,165, 325,862, and 332,336, [all in Class 32, Distilling &c.], are referred to.