GB925469A - Improvements relating to a process for the concentration and purification of acetylene and olefinic hydrocarbons contained in pyrolysis gases - Google Patents

Abstract

In the purification of pyrolysis gases containing acetylene and olefins, from which carbon and tars have been removed, by dissolving hydrocarbons containing more than two carbon atoms (e.g. higher acetylenes) in a hydrophilic solvent, the solvent, after stripping out the major portion of dissolved hydrocarbons, is contacted with an aqueous solution of caustic alkali and a hydrocarbon or mixture of hydrocarbons of molecular weight above 100, immiscible with and differing in density from the hydrophilic solvent whereby remaining dissolved hydrocarbons are sorted out of the solvent and extracted in the hydrocarbon(s) and thereafter the aqueous phase is separated and distilled to recover the solvent. The solvent may be methanol or acetone and to it is added 0,5-5 parts, per part by volume of solvent, of 1-5% aqueous alkali and for each part by volume of aqueous solvent is used 0,02-0,2 part of hydrocarbon which is preferably an aromatic hydrocarbon mixture such as a coke oven middle distillate boiling in the range 250-285 DEG C. The aqueous solvent and hydrocarbon are preferably contacted at about 50 DEG C. either with mixing and settling or countercurrent extraction. Specifications 758,864 and 870,737 are referred to.