Experimental investigation on CO2 desorption kinetics from MDEA + PZ and comparison with MDEA/MDEA + DEA aqueous solutions with thermo‐gravimetric analysis method

The carbon dioxide discharged from fossil fuels combustion products is considered as a major contributor to global warming. The current investigation aimed at CO2 desorption kinetics in 3.25 mol L–1 methyldiethanolamine (MDEA)–0.1 mol L–1 piperazine (PZ) rich amine aqueous solution with thermo‐gravimetric analysis (TGA) method under different heating rates of 2.5, 5, 10, and 20 °C min–1. The kinetics parameters were determined by comparison of 40 mechanism functions with thermal analysis kinetic method. The average activation energy E was 59.16 kJ mol–1, preexponential factor A was 5.54 × 108, and the most probable mechanism function was G(α) = [–ln(1 – α)]3/2. In addition, the kinetic parameters of CO2 desorption process from three rich amine aqueous solutions (MDEA, MDEA + diethanolamine(DEA), MDEA + PZ) were compared and the influence of kinetic parameters was further discussed. The desorption rate models of three rich amine aqueous solutions were established and desorption rates were well predicted. The order of desorption rate inferred from desorption rate model was MDEA > MDEA + DEA > MDEA + PZ. The results indicated that TGA combined with thermal analysis kinetics was an effective and quick method with high accuracy, easy operation, and good repeatability for screening absorbents preliminarily in laboratory. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.