Experimental and DFT Mechanism Study on the Effect of SO2 on CO2 Adsorption Performance by K2CO3

The exhaust gas of power plant boiler contains trace SO2 after desulphurization, resulting in poor performance of CO2 adsorbent. In this paper, according to the composition of flue gas in power plant, CO2 adsorption performance of K2CO3 adsorbent and the effect of SO2 on CO2 adsorption are studied by using simulated flue gas under laboratory conditions. Combined with XRD analysis, density functional theory (DFT) is used to study the effect of SO2 on K2CO3 adsorbent and the mechanism of CO2 adsorption. The results show that under the influence of the active s orbital of S atom in SO2 molecule, the p orbital of S and O atom are both more active, which degenerated to the valence band maximum of O atom on the surface of K2CO3. SO2 is preferentially adsorbed on O top site of K2CO3 surface and pushes CO2 away from the adsorbent surface, resulting in the adsorbent’s active site being free but unable to adsorb CO2. It shows up in the experiment as follows: when the volume concentration of CO2 in the simulated flue gas is 10%, SO2 with a volume concentration of 0.007% in the atmosphere will reduce the adsorption capacity of the adsorbent from 1.65mmol/g to 1.01mmol/g. The adsorption mechanism of CO2 and H2O on the surface of K2CO3 (001) is proposed. The theoretically calculated reaction activation energy and reaction heat are 40.7kJ/mol and -54.9kJ/mol, respectively. ©2024 Chin.Soc.for Elec.Eng.