GB377193A - Improvements in the separation of unsaturated hydrocarbons from gas mixtures containing the same - Google Patents

Abstract

The separation of gaseous hydrocarbons having a triple carbon linkage, such as acetylene, from gas mixtures is effected by washing the mixtures with liquefied substances which under atmospheric pressure are gaseous at 15 DEG C. and condensable at a temperature above 100 DEG below 0 DEG C., but other than substances chemically converting the unsaturated hydrocarbons during the washing operation, such as chlorine, and substances themselves composed of unsaturated hydrocarbons. Suitable substances are those which may be used as cooling agents in refrigerating plants, e.g. liquid sulphur dioxide, ammonia, carbon dioxide, methyl chloride and ethyl chloride. These bodies may also be used to attain the low temperature required for the washing operation. The washing treatment may be carried out at pressures from atmospheric up to 1000 atmospheres. When using carbon dioxide, the process is carried out at temperatures above -56 DEG C. and pressures above 15 atmospheres. The solvent vapours may be recovered by absorption, e.g. in water or in dilute sulphuric acid in the case of ammonia, or the solvent vapour and the unsaturated hydrocarbons may be treated to cause chemical reaction, e.g. a mixture of ammonia and acetylene may be led, with the addition of steam, at a temperature of about 350 DEG C. over zinc sulphate deposited on silica gel. Nitrogenous bases such as pyridine are obtained. The process may also be used for splitting up mixtures of, or the separate recovery of unsaturated hydrocarbons of differing degrees of unsaturation from gas mixtures. For example, acetylene and ethylene may be separated, the acetylene being practically completely absorbed in the above described solvents.ALSO:The separation of acetylene from gas mixtures is effected by washing the mixtures with liquefied substances which under atmospheric pressure are gaseous at 15 DEG C. and condensable at a temperature above 100 DEG below 0 DEG C., but other than substances chemically converting the unsaturated hydrocarbon during the washing operation, such as chlorine, and substances themselves composed of unsaturated hydrocarbons. Suitable substances are those which may be used as cooling agents in refrigerating plants, e.g. liquid sulphur dioxide, ammonia, carbon dioxide, methyl chloride and ethyl chloride. These bodies may also be used to obtain the low temperatures required for the washing operation. The washing treatment may be carried out at pressures from atmospheric up to 1000 atmospheres. When using carbon dioxide, the process is carried out at temperatures above -56 DEG C. The solvent vapour and the unsaturated hydrocarbons may be treated after the separation to cause chemical reaction, e.g. a mixture of ammonia and acetylene may be led, with the addition of steam, at a temperature of about 350 DEG C. over zinc sulphate deposited on silica gel. Nitrogenous bases such as pyridine are obtained.