Patent GB-450519-A (GB)
Title: Improvements in the removal of gaseous weak acids from gases containing the same
IPC: B01D53/52
Filed: 1935-01-24
Abstract: For recovering weak gaseous acids, such as hydrogen sulphide, carbon dioxide and sulphur dioxide, from gases, use is made of liquids comprising bases containing at least two atoms of nitrogen and corresponding to the general formula <FORM:0450519/IV/1> in which B is an aliphatic hydrocarbon radicle which may contain a simple or substituted amino group, at least one of the groups A is an alkyl or aryl group (which may contain a hydroxyl group or a simple or substituted amino group), or two of the groups A attached to different nitrogen atoms form an alkylene group, while the remaining groups A are hydrogen, alkyl or aryl groups, the washing liquid being regenerated by heating whereby the absorved acid gases are expelled. The following compounds may be employed: CH3.NH.CH2.CH2. NH.C2H4OH obtainable from methylbromethylamine and monoethanolamine: (CH3)2: N.CH2. CH2.NH.C2H4.OH obtainable from dimethyl-ethylenediamine and ethylene oxide: HO.C2H4. NH.CH2.CH2.NH.C2H4OH obtainable from ethylene chloride and monoethanolamine; (HO.C2H4)2 : N.CH2.CH2.N : (C2H4OH)2 obtainable from ethylene chloride and diethanolamine; H2N.CH2.CH2.N(CH3).C2H4OH obtainable from methyl ethylenediamine and ethylene oxide; methyl ethylenediamine and ethylene oxide; HO.C2H4.N(CH3).CH2.CH2.N(CH3). C2H4OH obtainable from ethylene chloride and methylethanolamine; HO.C2H4.NH.CH2.CH2.NH. CH2.CH2.NH.C2H4.OH obtainable from ethylene oxide and diethylene triamine; CH3.NH. CH2.CH2.NH.CH2.CH2.NH.C2H4OH obtainable from methyldiethylene triamine and ethylene oxide; HO.C2H4.N(CH3).CH2.CH2.NH. CH2. CH2.NH2 obtainable from methylethanolamine and bromethyl ethylene-diamine; CH3.NH. CH2.CH2.N(C2H4.OH).CH2.NH2.NH. CH3 obtainable from dimethyl diethylenetriamine and ethylene oxide; HO.C2H4.NH.CH2.CH2. NH.CH2.CH2.NH.CH2.CH2.NH2 obtainable from ethylene chlorhydrin and triethylene-tetramine; HO.C2H4.NH.CH2.CH2.NH.CH2 CH2.NH.CH2.CH2.NH.C2H4.OH obtainable from di-(bromethyl)amine, monoethanolamine and hydroxyethyl ethylene - diamine; (HO.C2H4)2 : N.CH2.CH2.NH.CH2. CH2.NH. CH2.CH2.NH2 obtainable from diethanolamine and bromethyl-diethylenetriamine; CH3.NH. CH2.CH2.N(CH3).CH2.CH2.N(CH3). CH2.CH2. NH.CH3 obtainable from methylamine and dibromethyl - dimethyl - ethylenediamine; C6H5.N(CH3).CH2.CH2.NH. C2H4.OH obtainable from phenyl-methyl-bromethylamine and monoethanolamine; (C6H4.NH2)N(CH3). CH2. CH2.N(CH3).CH2.CH2.N(CH3).CH2. CH2.N (CH3).C2H4.OH obtainable from aminophenylmethyl - bromethylamine and trimethyl - hydroxyethyl - diethylenetriamine; (C6H4.NH2 N(CH3).CH2.CH2N(C6H4NH2) CH2.CH2N(C6 H5.C2H4.OH obtainable from methylparaphenylene diamine, phenyl - monoethanolamine and N.N. - di - bromethyl - orthophenylene diamine. Specific examples refer to the preparation of the base dihydroxyethyl-ethylenediamine by reacting one mol. of ethylene diamine with two mols. of ethylene oxide and the preparation of monomethylmonohydroxyethyl - triethylene - tetramine by reacting one mol. of triethylene tetramine with one mol. of ethylene oxide and treating the product with one mol. of methyl iodide.ALSO:Weak gaseous acids, such as hydrogen sulphide, carbon dioxide and sulphur dioxide, are recovered from gases by washing the gases with a liquid comprising a base containing at least two atoms of nitrogen and corresponding to the general formula <FORM:0450519/III/1> in which B is an aliphatic hydrocarbon radicle which may contain a simple or substituted amino group, at least one of the groups A is an alkyl or aryl group (which may contain a hydroxyl group or a simple or substituted amino group) or two of the groups A attached to different nitrogen atoms form an alkylene group while the remaining groups A are hydrogen, alkyl or aryl groups, the washing liquid being regenerated by heating whereby the absorbed acid gases are expelled. Such of the bases that are liquids may be used directly as such, the salt of the absorbed weak acid usually separating in a solid form. The separated salt may be continuously or discontinuously separated and heated for the regeneration of the base, the base being returned to that part used for washing at the same rate as the salt is removed.  The bases may also be used in solution in water or in media such as cresol or washing oil.  With the latter solvents gases such as coke oven gases can be simultaneously washed for the removal of benzene.  The washing step may be conducted at normal, elevated or lowered temperature and under any desired pressure, e.g. elevated pressure.  The heating for regeneration may be effected by direct or indirect steam, direct fire or hot combustion gases &c. in suitable apparatus such as towers.  By suitably selecting the group A the solubility and/or basicity of the bases may be varied as required. For example, comparatively weak bases may be used to absorb sulphur dioxide only in the presence of carbon dioxide. The following compounds may be employed: CH3.NH.CH2. CH2.NH.C2H4OH obtainable from methylbromethylamine and monoethanolamine, (CH3)2 : N.CH2.CH2.NH.C2H4.OH obtainable from dimethylethylenediamine and ethylene oxide, HO.C2H4.NH.CH2.CH2.NH.C2H4OH obtainable from ethylene chloride and monoethanolamine, (HO.C2H4)2 : N.CH2.CH2.N : (C2H4OH)2 obtainable from ethylene chloride and diethanolamine, H2N.CH2.CH2.N (CH3).C2H4OH obtainable from methyl ethylenediamine and ethylene oxide, HO.C2H4.N(CH3). CH2.CH2.N(CH3).C2H4OH obtainable fro ethylene chloride and methylethanolamine, HO.C2H4.NH.CH2.CH2.NH.CH2.CH2. NH.C2H4. OH obtainable from ethylene oxide and diethylene triamine, CH3.NH.CH2.CH2.NH.CH2. CH2.NH.C2H4OH obtainable from methyldiethylene triamine and ethylene oxide, HO. C2H4.N(CH3).CH2.CH2.NH.CH2. CH2.NH2 obtainable from methylethanolamine and bromethyl ethylene-diamine, CH3.NH.CH2.CH2. N(C2H4.OH).CH2.CH2.NH.CH3 obtainable from dimethyl diethylenetriamine and ethylene oxide, HO.C2H4.NH.CH2.CH2.NH.CH2.CH2. NH.CH2. CH2.NH2 obtainable from ethylene chlorhydrin and triethylenetetramine, HO.C2H4.NH.CH2. CH2.NH.CH2.CH2.NH.CH2.CH2.NH.C2\t   H4.OH obtainable from di-bromethylamine, monoethanolamine and hydroxyethyl ethylene-diamine, (HO.C2H4)2 : N.CH2.CH2.NH. CH2.CH2. NH.CH2.CH2.NH2 obtainable from diethanolamine and bromethyl diethylenetriamine, CH3.NH.CH2.CH2.N(CH3).CH2.CH2. N(CH3). CH2.CH2.NH.CH3 obtainable from methylamine and dibromethyl dimethyl ethylenediamine, C6H5.N(CH3).CH2.CH2.NH. C2H4.OH obtainable from phenyl methyl bromethylamine and monoethanolamine, (C6H4.NH2)N(CH3). CH2.CH2.N(CH3).CH2.CH2.N(CH3). CH2.CH2.N (CH3).C2H4.OH obtainable from aminophenyl methyl bromethylamine and trimethyl hydroxyethyl diethylenetriamine, (C6H4.NH2).N (CH3). CH2.CH2.N(C6H4NH2).CH2. CH2.N(C6H5).C2H4 OH obtainable from methyl-para-phenylene diamine, phenyl-monoethanolamine and N.N.-di-bromethyl-orthophenylene diamine. Piperazine and its derivatives may also be employed.  Specific examples are given of the employment of a solution in washing oil of the base dihydroxyethyl-ethylenediamine obtainable by reacting one mol of ethylene diamine with two mols of ethylene oxide and the employment of an aqueous solution of monomethylmonohydroxyethyl - triethylene - tetramine obtainable by reacting one mol of triethylene tetramine with one mol of ethylene oxide and treating the product with one mol of methyl iodide.  The Specification as open to inspection under Sect. 91 comprises also the employment of corresponding compounds containing benzyl, naphthyl or pyridyl groups or pyrazine or its derivatives and compounds in which at least one of the Groups A is a simple or substituted amino group.  It also refers to the use of <FORM:0450519/III/2> and monohydroxymethyl-di-ethylenetriamine.  This subject-matter does not appear in the Specification as accepted.