Regeneration reaction characteristics and mechanism model of K2CO3/Al2O3 sorbent for CO2 capture

Abstract

AbstractThe regeneration reaction characteristics of the K2CO3/Al2O3 sorbent were investigated with a thermogravimetric apparatus. The effects of the gas composition and temperature on the regeneration conversion and reaction rate were analysed extensively. The results of the thermogravimetric experiment revealed that the regeneration characteristics of K2CO3/Al2O3 are better than those of pure K2CO3 and that temperature is the key parameter for the K2CO3/Al2O3 regeneration process. It was also observed that the regeneration process of K2CO3/Al2O3 occurred in three stages. As the regeneration temperature increased, regeneration occurred in the following sequence: KHCO3 on the external surface, KHCO3 on the internal surface and KAl (CO3)2(OH)2. The activation energy (E, kJ/mol) and pre‐index factor (A, min−1) of the three stages were 69.7, 73.8 and 84.5 and 1.36 × 107, 1.86 × 107 and 2.74 × 106, respectively. The reaction kinetic parameters were calculated by the thermal analysis method. A comprehensive model based on the Avrami–Erofeev reaction mechanism model was proposed for the regeneration process of K2CO3/Al2O3. The model data and test values agreed well, thereby establishing the model's accuracy. This paper provides fundamental data for further study on the capture of carbon dioxide from flue gas using potassium‐based sorbents.