Patent GB-470440-A (GB)
Title: Improvements in the removal of weak gaseous acids from gases
IPC: B01D53/52
Filed: 1936-09-14
Abstract: Weak gaseous acid such as carbon dioxide, sulphur dioxide and sulphuretted hydrogen, are recovered from gases containing them by washing the gases with a liquid comprising polymerization products of alkylene-imines, preferably ethylene-imine, or derivatives of these polymerization products, and regenerating the washing liquid for the recovery of the weak gaseous acids and the initial polymerization products.  The polymerization products may be prepared as set forth in Specification 461,354.  The Specification as open to inspection under Sect. 91 refers also to the use of polymerized propylene-imine, C-methylethylene-imine, C - ethyl - ethylene - imine, C-butylethylene - imine, N - methyl - ethylene - imine, N - butyl - ethylene - imine, N - hexyl-ethylene-imine, N - dodecyl - ethylene - imine, or N-octodecyl - ethylene - imine, N - alkyl - derivatives being prepared by reacting ethylene-imine with an alkyl halide and then polymerizing, or by reacting the polymerized ethylene-imine with and alkyl halide to replace part or all of the hydrogen atoms attached to nitrogen.  Similarly, acyl derivatives, such as acetyl derivatives or deriviatve of lactic or stearic acid, may be prepared.  This subject-matter does not appear in the Specification as accepted.ALSO:Weak gaseous acids, such as carbon dioxide, sulphur dioxide, and sulphuretted hydrogen, are recovered from gases containing them by washing the gases with a liquid comprising polymerization products of alkylene-imines, preferably ethylene-imine or derivatives of these polymerization products, and regenerating the washing liquid for the recovery of the weak gaseous acids and the initial polymerization products.  The regeneration may be effected by heating.  The polymerization products may be prepared as set forth in Specification 461,354 [Group IV].  The above washing agents may be used alone or in admixture with other basic substances e.g. basic-reacting salts of organic acids, tertiary potassium phosphate or potassium metaborate.  The washing agents may be dissolved in aqueous or non-aqueous media.  Specification 450,519, also is referred to.  The Specification as open to inspection under Sect. 91 refers also to the use of polymerized propylene-imine, C-methylethylene-imine, C-ethyl-ethylene-imine, C-butyl-ethylene imine, N-methyl-ethylene-imine, N-butyl-ethyl ene-imine, N-hexyl-ethylene-imine, N-dodecyl-ethylene-imine, or N-octadecyl-ethylene-imine, N-alkyl derivatives being prepared by reacting ethylene-imine with an alkyl halide and then polymerizing, or by reacting the polymerized ethylene-imine with an alkyl halide to replace part or all of the hydrogen atoms attached to nitrogen. Similarly acyl derivatives such as acetyl derivatives or derivatives of lactic or stearic acid, may be prepared and used.  The gases to be treated may be subjected to a preliminary treatment, e.g. with solutions of alkali or ammonium polysulphides or with a suspension of iron hydroxide, to remove cyanogen compounds.  This subject-matter does not appear in the Specification as accepted.