GB508764A - Improvements in the manufacture and production of butadiene from butane - Google Patents

Abstract

508,764. Catalytic dehydrogenation. I. G. FARBENINDUSTRIE AKT.-GES. Oct. 17, 1938, No. 30031. Convention date, Oct. 20, 1937. [Class 1 (i)] [Also in Group IV] Butadiene is prepared by catalytic dehydrogenation of butane to butylene, isolation of this from the reaction mixture, and further dehydrogenation to butadiene. Conversion of butane to butylene may be effected at 500-600‹ C. with alumina activated by oxides of chromium, vanadium, tungsten or molybdenum so that only up to about 35 per cent conversion is obtained. The butylene is separated and, if necessary after further purification, is dehydrogenated in the presence or absence of catalysts preferably only up to about 30 per cent conversion to butadiene. In an example, the first dehydrogenation is effected at 500-520‹ C. with an alumina catalyst containing 5 per cent of chromium oxides. These may be prepared by reducing chromic acid or aluminium chromate in hydrogen, in the latter case part of the necessary alumina being simultaneously obtained. The separated butylene is led, together with 10 parts of carbon dioxide, over porcelain or quartz at 680‹ C. at such a speed that 25-30 per cent conversion to butadiene is effected, Specification 481,646 is referred to. The Specification as open to inspection under Sect. 91 comprises an additional example wherein butane is dehydrogenated at 520‹ C., using an alumina-vanadium oxide catalyst which can be regenerated by air, oxygen or steam or mixtures thereof. The separated butylene is diluted with 3-4 parts of steam and further dehydrogenated at about 700‹ C. This subject-matter does not appear in the Specification as accepted.