GB516659A - A process for the manufacture of isobutane from normal butane - Google Patents

Abstract

516,659. Isomerization of butane. NAAMLOOZE VENNOOTCHAP DE BATAAFSCHE PETROLEUM MAATSCHAPPIJ. Aug. 4, 1938, No. 23103. Convention date, Feb. 12, 1938. [A Specification was laid open to inspection under Sect. 91 of the Acts, Feb. 20, 1939.] [Class 2 (iii)] Isobutane is obtained by contacting n-butane or mixtures containing it, preferably in the gas phase, at below about 200‹C. with a catalyst consisting of aluminium chloride, and a carrier comprising an inorganic substance containing water which normally can only be split off at about 200‹C. Such substances include kaolins, e.g. pipe clay, pyrophyllite, apophyllite, meerschaum, serpentine, and kieserite, which may be heated above 200‹C., but not so strongly as to drive off all the combined water, and alumina or silica gel, which may be prepared by heating the hydroxides say to about 250‹C. and thus still contain a few per cent. of water. Other catalysts or inert substances, e.g. pumice, chamotte, or quartz, or small'quantities of water or hydrogen chloride may also be present. Pressure may be ordinary, elevated or reduced. The process may be continuous and the isobutane formed removed by raising the temperature and/or reducing the pressure. In an example, a mixture of butanes is passed at 150‹C. with a contact period of 93 secs. over a mixture of aluminium chloride, and pipe clay dried at 300‹C. which has been compressed to pastilles. With pipe clay dried at 1100‹C., a much smaller conversion is obtained. Specification 498,512 is referred to. The Specification as open to inspection under Sect. 91 comprises also the use of carriers in general, e.g. pumice, silica, and " Permutite " (Registered Trade Mark). Temperatures preferably do not exceed 150-160‹C., and pressure of 10 atmos. or more may be used. The aluminium chloride may be employed in the form of its double compounds with aromatic hydrocarbons particularly those containing alkyl groups, e.g. butyl or tripropyl benzene. Organic compounds yielding hydrogen chloride under the reaction conditions, e.g. tertiary butyl chloride or secondary butyl alcohol, may be added. Examples describe the treatment of mixed butanes with aluminium chloride at 150‹C. using pumice as the carrier, at 120‹C. and 11 atmos. with pipeclay dried at 300‹C. as carrier, and at 120‹C. or at 100‹C. and 11 atmos. with a carrier consisting of alumina prepared from the hydroxide and dried at 300‹C. The butanes may be mixed with hydrogen chloride or previously bubbled through water at 20‹C. or secondary butyl alcohol or tertiary butyl chloride at 40‹C. This subject-matter does not appear in the Specification as accepted.