GB258576A - Improvements in the purification of crude benzol - Google Patents

Abstract

258,576. I. G. Farbenindustrie Akt.- Ges. Sept. 15, 1925, [Convention date]. Tar oils, purifying, extracting, &c.-Crude benzol is desulphurized and otherwise purified by treatment at high temperature and elevated pressure and in presence of a catalyst with hydrogen or gases containing or producing hydrogen under the conditions of working. In an example crude benzol containing thiophene is passed in a current of hydrogen at 460‹ C. and 200 atmospheres through an aluminium-lined vessel containing a contact mass prepared by pressing a mixture of molybdic acid and zinc oxide. The product is light in colour, free from unsaturated compounds and thiophene, and gives pure benzol and a small proportion of other lowboiling hydrocarbons on distillation. In a second example, crude benzol obtained by steam distilling an oil used for washing gases containing benzol is passed in a current of nitrogen and hydrogen at 450‹ C. and 150-200 atmospheres over a pressed mixture of molybdic acid and magnesium oxide. The product is fractionally distilled into pure benzol and a mixture of other hydrocarbons of low boiling point. Contact masses specified are those immune from sulphur poisoning used in the destructive hydrogenation of coal &c., e.g. those containing molybdenum, tungsten, or chromium. The pressures are preferably over 50 atmospheres.