Kinetics of CO2 absorption in aqueous N,N-diethylethanolamine and its blend with N-(2-aminoethyl)ethanolamine using a stirred cell reactor

The absorption of CO2 into an aqueous solution of N,N-diethylethanolamine (DEEA) is studied at 293, 303, and 318 K within the amine concentration range of 0.8-2 kmol m(-3) using a stirred cell with a flat gas-liquid interphase. Absorption rate experiments are carried out in the pseudo-first-order regime, which enabled determination of the kinetics from the fall-in pressure method. The second-order rate constants for the CO2 reaction with DEEA are obtained and then compared to the scarce literature data. At 303 K, the obtained reaction rate constant equals 65.5 m(3) kmol(-1) s(-1). The activation energy is calculated to be 41.461g/mol. Additionally, the absorption of CO2 into aqueous solutions of DEEA activated with N-(2-aminoethyl) ethanolamine (AEEA) is studied at 303 K. Three formulated solvents (2 M DEEA + 0.1 M AEEA), (2 M DEEA + 0.2 M AEEA) and (2 M DEEA+ 0.3 M AEEA) were investigated. The enhancement factor in the blended solution is significantly higher than for the pure DEEA solution. The overall reaction in amine blends can be regarded as a reaction between CO2 and DEEA in parallel with the reaction of CO2 with AEEA. It has been proven that the kinetic rate constants for the CO2 reaction with DEEA and AEEA, which were determined using the present experimental technique, can satisfactorily predict the measured kinetics for the aqueous amine blends DEEA/AEEA under pseudo-first-order regime. (C) 2015 Elsevier Ltd. All rights reserved.