Acid gas scrubbing methods featuring amine phase separation for hydrogen sulfide capture

A method comprising:

• contacting a gas mixture comprising hydrogen sulfide with an aqueous solution comprising an amine in an absorber tower under kinetically controlled contacting conditions;
• wherein the amine has a higher binding selectivity for hydrogen sulfide than for carbon dioxide under the kinetically controlled contacting conditions, wherein binding selectivity for hydrogen sulfide over carbon dioxide is specified by the ratio
• (
• [
• H
• 2
• ⁢
• S
• ]
• /
• [
• CO
• 2
• ]
• )
• aqueous
• ⁢
• solution
• (
• [
• H
• 2
• ⁢
• S
• ]
• /
• [
• CO
• 2
• ]
• )
• gas
• ⁢
• mixture
• wherein ([H2S]/[CO2])aqueous solution is a molar ratio of hydrogen sulfide to carbon dioxide in the aqueous solution and ([H2S]/[CO2])gas mixture is a molar ratio of hydrogen sulfide to carbon dioxide in the gas mixture, wherein the ratio is greater than or equal to 8;
• and wherein the aqueous solution undergoes liquid phase separation above a critical solution temperature;
• forming a reaction product of the hydrogen sulfide and the amine in the aqueous solution;
• heating the aqueous solution to a temperature greater than or equal to the critical solution temperature, thereby forming a light phase comprising the amine and a heavy phase comprising water;
• wherein a majority of the reaction product of the hydrogen sulfide and the amine is present in either the light phase or the heavy phase;
• separating the light phase from the heavy phase;
• processing one of the light phase or the heavy phase to remove at least some hydrogen sulfide therefrom;
• and
• after separating the light phase from the heavy phase, recycling at least a portion of the light phase to the absorber tower.