Selective absorption of H2S from gas mixtures into aqueous solutions of blended amines of methyldiethanolamine and 2-tertiarybutylamino-2-ethoxyethanol in a packed column

In this work, an experimental investigation for selective absorption of H2S from gas-mixed streams into an aqueous blend of methyldiethanolamine (MDEA) and 2-tertiarybutylamino-2-ethoxyethanol (TBEE) in a packed column at atmospheric pressure and a constant liquid flowrate was performed. TBEE, a severe sterically hindered amine, was added into MDEA to form the blended amines. The effect of H2S loading of lean-solution, temperature of lean solution, the mole ratio of CO2/H2S in gas mixtures, and the gas flowrate on absorption performance were investigated by means of the evaluation of removal efficiency and selectivity factor. Based on the mass balance, overall volumetric mass-transfer coefficient (KGa) of H2S was determinated. The performance of simultaneous absorption of CO2 and H2S into the aqueous blend of MDEA and TBEE is compared with that of the single aqueous solution of MDEA. The effect of gas flowrate, H2S and CO2 concentration of gas-phase on KGa of H2S were studied also. The aqueous blend of MDEA and TBEE has been found to be an efficient mixed solvent for selective H2S removal. The experimental results also testified the advantages of severe sterically hindered amines (e.g., TBEE) over traditional amines in selective H2S absorption. This work provides the useful results for the aqueous blended amines containing sterically hindered amines to be extensively applied in the field of selective H2S removal.