GB524918A - Improvements in the manufacture and production of butadiene - Google Patents

Abstract

524,918. Catalytic dehydrogenation. JOHNSON, G. W. (I. G. Farbenindustrie Akt.-Ges.). June 13, 1938, Nos. 17540/38 and 12265/39. [Class 1 (i)] [Also in Group IV] Butadiene is prepared by the dehydrogenation of butylene by a process characterized in that a gaseous mixture of normal butylene and steam is passed at a temperature of 500‹- 700‹C. over a catalyst comprising more than 50 per cent. of zinc oxide together with one or more oxides or salts of the oxy acids of chromium, vanadium, molybdenum, uranium or tungsten. The amount of activating oxide used is preferably small such as from 10 per cent. down to 1 per cent. The catalysts are preferably free from iron. The mixture of butylene and steam should be led over the catalyst at a high velocity so that only a part of the butylene is reacted. The activating oxides may be used in various forms, chromium in the form of chromic oxide or chromic acid anhydride, or in the form of chromates or chromites and vanadium, molybdenum, uranium and tungsten in the form of vanadic, molybdic, uranic or tungstic acid anhydrides or in the form of salts of the corresponding acids. The catalysts are prepared by precipitating the activating oxides on the zinc oxide or by mixing zinc oxide with salts, preferably zinc salts of the activating oxides and then heating the mixture in hydrogen. In addition to zinc oxide, other basic oxides such as alkaline earth oxides may be present. The preferred starting material is beta-butylene or mixtures of normal butylenes with beta-butylene. In the following examples a steel tube the interior of which is lined with copper containing a small amount of manganese is used as the reactor (1) 20 parts by volume of alpha-butylene and 80 parts by volume of betabutylene diluted with six times the volume of steam is passed over a catalyst consisting of 90 per cent. zinc oxide and 10 per cent. chromium oxides with a contact time of 0.5 seconds, to give a 20 per cent. yield of butadiene. (2) Beta-butylene and steam is led at 600‹C. over a catalyst comprising 80 parts zinc oxide, 20 parts aluminium oxide and 10 parts calcium chromate as in example (1). (3) Beta-butylene and steam is passed over 60 parts zinc oxide, 20 parts aluminium oxide, and 10 parts calcium oxide impregnated with chromium nitrate and heated. (4) Beta-butylene and steam is passed over zinc oxide on which 1.5 per cent. molybdic acid amhydride has been precipitated. (5) Beta-butylene and steam is passed over 65 parts of zinc oxide and 30 parts of calcium aluminate impregnated with an amount of ammonium vanadate such that on heating the catalyst contains 5 per cent. of vanadium oxide. (6) Butylene and steam is passed over zinc oxide containing 5 per cent. of ammonium uranyl acetate. (7) Beta-butylene and steam is passed over a mixture of 95 per cent. zinc oxide and 5 per cent. chromium oxide.