GB886338A - Process for separating carbon monoxide from gaseous mixtures - Google Patents

Abstract

Carbon monoxide is removed from an olefinfree gas by absorption in an aqueous solution containing one or more amines and mono- and divalent copper, 5-20%, preferably 10-15%, of the copper being in the divalent form. The solution preferably contains 200 gm./1 of copper. The gas treated may contain hydrogen, nitrogen, carbon monoxide, and methane. The amine may be an alkanolamine, e.g. ethanolamine, propanolamine, or diethanolamine. The absorbent solution may be prepared by heating a mixture of cuprous oxide, ammonium nitrate, monoethanolamine and water, driving off the ammonia set free, and partially oxidizing the resulting cuprous solution. The cuprous solution may alternatively be prepared by interacting cuprous oxide an aqueous nitric acid in the presence of mono-ethanolamine, or by dissolving copper in an aqueous ammonium salt solution containing an alkanolamine in the presence of air or oxygen. Carbonate, chloride, acetate, or formate ions may be present instead of nitrate ions. The cuprous solution may be oxidized with air or oxygen at a temperature of 30 DEG -70 DEG C., and under a gauge pressure of 0-50 atmos. Absorption may be effected at a temperature of 0 DEG -30 DEG C., preferably 0 DEG -20 DEG C., and a gauge pressure of 1-50 atmos, preferably 10-30 atmos. Desorption may be effected at a temperature of 30 DEG -70 DEG C., preferably 40 DEG -60 DEG C., and under an absolute pressure of 0,1-2 atmos. The desorbed solution may be recycled to the absorption step. Partial reduction of the absorbent solution may be allowed to take place, the solution being reoxidized between the steps of desorption and recycling. Alternatively partial reduction may be prevented by carrying out the absorption in the presence of oxygen.