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

[Display omitted] •SrO as a support agent enhances the thermal stability of MgO-AMS adsorbents.•The adsorption process of MgO-SrO for CO2 mainly involves chemical adsorption.•MgO-SrO materials have good thermochemical energy storage properties.•The doping mechanism of SrO was investigated using the VdW-corrected DFT method. Alkali metal molten salts (AMS) have shown exceptional potential in enhancing the CO2 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 CO2 adsorption at moderate temperatures. Adsorption kinetics revealed that the chemisorption process dominated the CO2 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 CO2 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.