GB509540A - A process for producing isobutane from normal butane - Google Patents

Abstract

509,540. Isomerization of butane. NAAMLOOZE VENNOOTSCHAP DE BATAAFSCHE PETROLEUM MAATSCHAPPIJ Aug. 4, 1938, Nos. 23100 and 23101. Convention dates, Aug. 18, 1937, arid June 10, 1938. [Class 2 (iii)] Isobutane is produced by contacting nbutane or n-butane-containing mixtures substantially free from olefines, in the liquid phase at normal or raised temperatures not exceeding 110‹C., with an aluminium chloride catalyst in the presence of hydrogen halide, preferably hydrogen chloride. The latter may be present in small amount but preferably has a partial pressure of at least about 3 atmospheres. At above about 70 ‹C. with a HC1 partial pressure of 4 atmospheres, more than 50 per cent. of the butane can be isomerized in a few hours. The process may be continuous, and the isobutane removed by raising the temperature and/or reducing the pressure. In examples, a mixture of n- and iso-butanes is treated with about half its weight of aluminium chloride in a rotating autoclave. HC1 is introduced until its partial pressure varies from 3-20 atmospheres at 20‹C. Reaction temperatures up to 100‹C. with contact times of 4-64 hours are used. At 120‹C. little isomerism but extensive decomposition occurs. Specification 498,512 is referred to. The Specification as open to inspection under Sect. 91 comprises also the use of an aluminium bromide catalyst, optionally in the presence of hydrogen halide, this being the subjectmatter of Specification 512,408. It also includes the use of aluminium chloride or bromide in the form of double compounds with aromatic hydrocarbons, e.g. butyl-or tripropyl-benzene. Additional examples describe the treatment of butane mixtures by shaking with aluminium bromide in a closed vessel at 30, 50 and 80‹C., hydrogen chloride optionally being present in the last case. This subject-matter does not appear in the Specification as accepted.