CO2 adsorption enhancement over alkaline metal-promoted MgO with SO2, O2, and H2O present: A theoretical study

The oxidizing abilities of SO2/O-2 & nbsp;and molecular polarity of H2O severely hamper CO2 & nbsp;adsorption on MgO via capturing surface electrons or occupying active sites. Therefore, it is crucial for MgO to gain better anti-SO2/O-2/H2O features. In this study, alkaline metals are introduced as promoters for MgO to counter negative effects of SO2/O-2/H2O. Through density functional theory (DFT) calculations, adsorption structures/energies, electron clouds/electron transfer, effects of temperatures are fully investigated to account for how adverse impacts of SO2/O-2/H2O are counteracted. Based on DFT calculation results, the average adsorption energies of CO2 & nbsp;on pure MgO are only 0.46,-6.54, and 2.41 kJ/mol with SO2, O-2, and H2O present, respectively. For Li-promoted MgO, the average adsorption energy of CO2 & nbsp;rises by about 65.51 kJ/mol with H2O present. As to Na-doped MgO, its average CO2 adsorption energy is raised by around 200 % with SO2 involved. As far as K-modified MgO is concerned, the average adsorption energy of CO2 is almost 5.0 times as big as the counterpart with O-2. Regarding Rb-amended MgO, its average adsorption strength of CO2 & nbsp;is raised to about -38.55 kJ/mol when being affected by H2O/SO2/O-2. What is more, it is proved that the desorption temperatures of CO2 rise a lot over promoted MgO owing to stronger electronic interaction. The research results could provide meaningful information for applying promoted MgO as a CO2 capturer in real industries.