CO2 adsorption and thermal stability improvement of MgO-SrO composite materials assisted by molten nitrate at medium temperature

Alkali metal molten salts (AMS) have shown exceptional potential in enhancing the CO 2 adsorption capacity of MgO-based sorbents at moderate temperatures. However, significant challenges still persist in terms of their thermal stability and recyclability due to sintering issues. In this study, a MgO-SrO composite sorbent was prepared using modified methanol evaporation-induced surface precipitation and promoted by molten nitrate to facilitate CO 2 adsorption at moderate temperatures. Adsorption kinetics revealed that the chemisorption process dominated the CO 2 adsorption on the surface of the MgO-SrO sorbent, with intraparticle diffusion being the main limiting step. Further investigation into the thermal stability and recyclability showed that the MgO-SrO sorbent retained good adsorption performance after 15 cycles of adsorption–desorption. By exploring the adsorption mechanism through Density functional theory (DFT) calculations, the participation mechanism of SrO during CO 2 adsorption was elucidated by examining the charge transfer and bonding strength of surface O atoms on the MgO. This study provides new insights for enhancing the thermal stability and recyclability of MgO-based sorbents under moderate temperature conditions.