Canadian Journal of Chemical Engineering, Vol.98, No.2, 556-565, 2020
New AMP/polyamine blends for improved CO2 capture: Study of kinetic and equilibrium features
2-Amino-2-methyl-1-propanol (AMP), which is the sterically hindered form of monoethanolamine (MEA), is a credible substitute to conventional CO2-capturing solvents. Its performance can be improved by blending with a highly reactive polyamine promoter. Two such aqueous blends of AMP/TETA and AMP/TEPA were chosen here (TETA = triethylenetetramine and TEPA = tetraethylenepentamine). The kinetics of CO2 absorption in the proposed blends was investigated at 308, 313, and 318 K using the stirred cell technique. The concentrations of AMP and polyamine were varied between 2 to 3 kmol/m(3) and 0.1 to 0.5 kmol/m(3), respectively. From the measured values of the fast pseudo-first order constants, the second-order rate constants for the reactions of CO2 with TETA (14 695 m(3)/(kmol s)) and TEPA (19 250 m(3)/(kmol s)) were determined at T = 313 K. Both TETA and TEPA react faster with CO2 than MEA. Further, the respective activation energy values were found (40 and 37 kJ/mol). Finally, the equilibrium solubility of CO2 for both blends was measured at T = 303 K. The loading capacity was higher than that for the aqueous blends of AMP/MEA, AMP/DEA, and AMP/MDEA (here, DEA and MDEA denote diethanolamine and N-methyldiethanolamine). The highest value of loading capacity (1.12 mol CO2/mol amine at 2.01 kPa equilibrium partial pressure of CO2) was noted in AMP/TEPA mixtures. The new findings on our proposed blends will strengthen the AMP/polyamine application in CO2 separation.