公开(公告)号：US3042483A

公开(公告)日：1962-07-03

申请号：US82898759

申请日：1959-07-23

Applicant: HOECHST AG

Inventor： ARTHUR WOLFRAM ,  HERBERT KALTENHAUSER ,  HARALD LORENZ ,  GUNTHER RELKEN

IPC: B01D47/00 ,  B01D53/14 ,  B01D53/62 ,  C01B32/50 ,  C10K1/14

CPC classification number: C10K1/143 ,  B01D47/00 ,  B01D53/1475 ,  B01D53/62 ,  C01B32/50 ,  Y02C10/04 ,  Y02C10/06 ,  Y02P20/152 ,  Y02P70/34

Abstract: Carbon dioxide is removed from gaseous mixtures by absorbing at below 60 DEG C. in an aqueous solution of a salt of an amino carboxylic or amino sulphonic acid capable of forming a carbamic acid with CO2, regenerating the loaded solution until the quantity of CO2 remaining therein is not greater than the value characterizing the position of the sharp bend in the curve of CO2 equilibrium partial pressure above the solution at the regeneration temperature against CO2 concentration in the solution, and does not differ from that value by more than 0,1 mol. CO2 per mol. salt, and absorbing CO2 from further gaseous mixture in the regenerated solution to an amount from 0,5-1,1 mols. CO2 per mol. salt. Absorption and regeneration may be carried out continuously. The position of the sharp bend is the position on the isotherm curves where the second differential of pCO2 is a maximum. Salts may be alkali metal, e.g. Na and/or K, salts of taurine, N-methyl taurine, N-methyl d -amino propionic acid, glycocoll, sarcosine, a -alanine, N-(b -ethoxy)-taurine, or N-(b -amino-ethoxy)-taurine, ox compounds of formula R-NH-R2-X-M, where R, is an H atom, or branched, or unbranched, or cyclic aliphatic radical which may contain an amino group, or an alcoholic, or ether oxygen, X is a -CO2- or -SO3-group, R2 is a branched, or unbranched, or cyclic alkylene radical having at least 2 C. atoms, and M is the cation of an inorganic or organic base. R1 preferably contains at most 8 C. atoms, e.g. methyl-cyclohexyl, cyclohexyl, hexyl, isobutyl, 2:5 dimethyl hexyl, propyl, ethyl, or methyl radicals. The solution may be 3,5-4,5 molar and may contain free amino acid, e.g. up to 25% to displace the position of the sharp bend to lower loadings. The acid may be the same as that in the salt, and may be produced by adding H2SO4 or HCl to the salt solution. Absorption may be under super-atmospheric pressures, e.g. up to 30 atms., and gas mixtures treated may be those containing 20% or less CO2, particularly those resulting from other scrubbing, e.g. with hot potassium carbonate. The regeneration may be with steam, which may be produced by boiling the solution, although steam may be introduced at a rate equal to that at which it is carried off with CO2. A gas inert to the solution, e.g. N2, H2, or air, may also be used to desorb the CO2, or subatmospheric pressure may be applied. Any of these methods of regeneration may be applied in association, preferably in stages with successively increasing temperatures, the last stage being 10-60 DEG C. higher than preceding stages. Other gases, e.g. acetylene or olefins dissolved from the mixture may be removed in the initial stages by an inert gas and/or by subatmospheric pressures, e.g. at 20-30 DEG C. below the boiling point of the solution under atmospheric pressure. With regeneration in a number of stages the pressure should not exceed atmospheric pressure throughout.