Adsorption mechanisms and regeneration heat analysis of a solid amine sorbent during CO2 capture in wet flue gas

H2O is an important fraction in industrial flue gas, and its impact on CO2 adsorption and energy consumption during CO2 capture in wet flue gas are important concerns by both industry and academia. This study investigated the adsorption mechanisms of CO2 and H2O and the corresponding regeneration heats of a commercial sorbent experimentally. By analyzing the adsorption isotherms of CO2 and H2O, it is found that the adsorption of CO2 and H2O on the sorbent is mainly chemisorption and multilayer physisorption respectively, which are also reflected by the measured adsorption heats. To evaluate the regeneration heat more accurately, a modified model was proposed, which considered the sensible heat required to heat the adsorbed H2O from adsorption to desorption temperature. By analyzing the influencing factors of regeneration heat based on the modified model, the heat due to the desorption of the co-adsorbed H2O in wet flue gas contributes the most. Further, energy-saving strategies e.g. increasing the adsorption temperature, reducing the H2O content of flue gases and using steam as the stripping gas during desorption are provided. In addition, increasing the CO2 working capacity and reducing the sorbent's affinity to H2O are two main improvement directions of the current solid amine sorbents.