Process for removing carbon dioxide containing acidic gases from gaseous mixtures using aqueous amine scrubbing solutions

In a process for substantially completely removing carbon dioxide containing gases from a normally gaseous feed, which comprises, in sequential steps:

• (1) contacting said feed with an aqueous scrubbing solution consisting essentially of an amine and water, wherein the total amine concentration in said solution is in the range from about 1 to about 6 molar, said contacting being conducted at a temperature ranging from about 20 to about 100.degree. C. and at a pressure ranging from about 5 to about 2000 psig to thereby absorb the carbon dioxide containing acidic gas in said scrubbing solution, and
• (2) regenerating said scrubbing solution at a temperature in the range from about 50.degree. to about 170.degree. C. and at a pressure ranging from about 1 to about 50 psia to thereby desorb the carbon dioxide containing gases from said scrubbing solution, the improvement which comprises:
• providing a sterically hindered amino alcohol selected from the group consisting of 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1-butanol, 3-amino-3-methyl-1-butanol, and 3-amino-3-methyl-2-butanol in said scrubbing solution as at least one of said amines, and operating said process at conditions whereby the difference between the moles of CO.sub.2 absorbed at the end of step (1) (absorption step) and the moles of CO.sub.2 absorbed at the end of step (2) (desorption step) would be at least 15% greater at thermodynamic equilibrium in the system (as determined from the vapor-liquid equilibrium isotherm in the reaction mixture) than in an aqueous amine CO.sub.2 scrubbing process wherein monoethanolamine is the only amine utilized under substantially the same conditions of gaseous feed composition, scrubbing solution composition, temperatures and pressures.