GB744080A - Improvements in or relating to a process for the utilization of acetylene and ethylene mixtures - Google Patents

Abstract

A mixture of acetylene and ethylene is reacted with chlorine in a liquid phase chlorhydrocarbon solvent, ethylene dichloride recovered from the products, and a residual gas stream enriched in acetylene recovered. The initial mixture may be obtained by cracking saturated hydrocarbons, e.g. natural gas, gasoline or naphtha, preferably an ethane fraction, at 1100-1600 DEG C. in tubular, regenerative or pebble furnaces, if desired with addition of steam or other inert gas, and separating a fraction containing acetylene and ethylene, preferably in equimolar proportions. The chlorination may be effected in carbon tetrachloride, tetrachlorethane, ethylene dichloride, chlorbenzene or trichlorbenzene at from room temperature up to about 125 DEG C., chlorination catalysts such as iron or its alloys or chlorides, antimony, zinc and aluminium chlorides, and iodine being present if desired. Ethylene is preferentially chlorinated and a small excess of chlorine over that required to form ethylene dichloride is preferred. A multistage process may be used giving substantially pure acetylene as residue. This may be reacted in a second stage, for example with hydrogen chloride as in Specification 744,079 to give vinyl chloride; with acetic acid to yield vinyl acetate as in Specifications 744,077 and 744,079; with hydrochloric acid as in Specification 744,081 to yield dichlorethylene; with hydrogen cyanide to yield acrylonitrile as in Specification 744,079; with an aldehyde or ketone as in the same Specification to yield alcohols after absorption of the acetylene in a suspension of potassium hydroxide as in Specification 744,082; with aqueous formaldehyde yielding butynediol-1,4, with alcohols containing sodium alcoholate to give vinyl ethers, or with benzene over an alkylation catalyst to form styrene, all as in Specification 744,079. By controlling the extent of conversion in this stage, a tail gas suitable for recycle with fresh feed to the first stage, as in that Specification 744,079, is obtained. In examples, the initial chlorination is effected in tetrachlorethane or ethylene dichloride with ferric or zinc chloride catalyst, residual acetylenic gas then being converted with hydrogen chloride over active carbon + barium chloride + trace of mercuric chloride to vinyl chloride; with hydrochloric acid to dichlorethylene; or with acetic acid to vinyl acetate.