Investigation of CO2 desorption kinetics in MDEA and MDEA+DEA rich amine solutions with thermo-gravimetric analysis method

In this paper, by means of thermo-gravimetric analysis(TGA), the desorption kinetics of CO 2 absorbed in two kinds of rich amine solutions, MDEA (3.25mol/L) and MDEA+DEA(3.25mol/L-0.3mol/L), were investigated under different heating rates(2.5℃/min, 5℃/min, 10℃/min and 20℃/min). The thermal analysis kinetics was applied to analyze the TG-DTG curves of two rich amine solutions so as to research CO 2 desorption kinetics. In addition, the CO 2 desorption kinetics parameters have been calculated with model-free method Flynn-Wall-Ozawa (FWO) and model-fitting method Coats-Redfern (CR). The results indicated that CO 2 desorption process could be divided into two stages. The CO 2 and H 2 O were released with non-uniform speed in the first stage and MDEA or DEA with higher boiling points were evaporated in the second stage. For MDEA solution the average activation energy E was 50.36kJ/mol, the pre-exponential factor A was 1.68×10 7 , and the most probable integral mechanism function was G α = α 3 / 2 . For MDEA+DEA solution the average activation energy E was 59.68kJ/mol, the pre-exponential factor A was 2.22×10 7 , and the most probable integral mechanism function was G α = [ ( 1 + α ) 1 / 3 − 1 ] 2 . The technical feasibility of CO 2 desorption performance in rich amine solutions with thermo-gravimetric analysis method was demonstrated.