GB467579A - Improvements in the removal of gaseous weak acids from gases containing the same - Google Patents

Abstract

The process described in the parent Specification in which weak gaseous acids such as hydrogen sulphide, carbon dioxide and sulphur dioxide are removed from gases, particularly fuel gases, by washing with a liquid comprising a base containing at least two atoms of nitrogen and corresponding to the general formula <FORM:0467579/IV/1> in which B is an aliphatic hydrocarbon radicle, is modified by using compounds wherein B contains at least one free or substituted hydroxyl group, preferably an etherified or esterified hydroxyl group, and each of the groups A is an alkyl, cyclo-alkyl, aryl or aralkyl group, substituted or not. Suitable substances are, for example, the acetic acid and dimethylaminoacetic acid esters of tetramethyl-diamino-isopropanol, and tetramethyl-diamino-isopropanol-ethyl ether (obtainable from the condensation product of a -dichlorhydrin and dimethylamine by esterifying with acetic or dimethylaminoacetic acid or converting the product into its ethyl ether), the condensation products from a -dichlorhydrin and methyl-b -oxyethylamine or N-methyl-N<1>-methyl-b -oxyethyl-ethylenediamine, and the methyl ether of the condensation product from a -dichlorhydrin and methylethylamine.ALSO:The process described in the parent Specification in which weak gaseous acids such as hydrogen sulphide, carbon dioxide and sulphur dioxide are removed from gases, particularly fuel gases, by washing with a liquid comprising a base containing at least two atoms of nitrogen and corresponding to the general formula <FORM:0467579/III/1> in which B is an aliphatic hydrocarbon radicle, is modified by using compounds wherein B contains at least one free or substituted hydroxyl group, preferably an etherified or esterified hydroxyl group. Each of the groups A is an alkyl, cyclo-alkyl, aryl or aralkyl group, substituted or not. The washing liquid is regenerated by heating whereby the absorbed acid gases are expelled. The compounds are used in solution in water or organic solvents. Suitable substances comprise the acetic acid ester of tetramethyl-diaminoisopropanol, tetramethyl - diaminoisopropanol - ethyl ether, and tetrahydroxyethyldiaminoisopropanol. Other impurities in the gases may be simultaneously removed by using a suitable solvent for the diamines such as a washing oil, when benzene is also removed. The washing liquids may be combined with other alkaline solutions, e.g. salts of amino acids, inorganic salts as potassium phosphate; or other basic washing liquids may be used in a succeeding step such as dimethylalanine potassium salt. The washing liquid may also be regenerated by passing it in countercurrent to a stream of steam, nitrogen, carbon dioxide, or vapours of organic substances such as chlorine derivatives of paraffins or benzene. The compounds used in the process may be obtained by reacting a -dichlorhydrin with a suitable amine such as dimethylamine, ethylamine, ethylene diamine or substituted derivatives thereof. The products obtained may be converted into their esters or ethers.