Synthesis of hollow Al-doped MgO spheres via a sacrificial templating method for enhanced CO2 adsorption

This paper presented the effect of the concentration of Mg(NO3)2·6H2O solution and Al doping on the structure, morphology and CO2 adsorption performances of MgO spheres. MgO-based spheres were synthesized through a sacrificial templating method using glucose-derived carbon spheres as the template and Mg(NO3)2·6H2O and Al(NO3)3·9H2O as precursors, and characterized by SEM, XRD, TEM, N2 adsorption/desorption, FT-IR and particle size analysis, respectively. The results demonstrated that hollow MgO spheres were formed with multiple shells, and the concentration of Mg2+ affected the crystallite size and average particle size. With Al incorporation, the crystallite size and average particle size of Mg/Al-10 was obviously reduced, which further influenced alkaline adsorption active sites and internal diffusion of CO2 molecules. As such, the adsorption capacity of the Al-doped adsorbent was greatly improved, for the tiny MgO nanocrystals can provide many more alkaline adsorption active sites and thus significantly advancing CO2 adsorption, while the small average particle size can shorten the diffusion distance of CO2 and increase the contact between the adsorbent and CO2. This work provided the inspiration of MgO-based adsorbent for promoting CO2 adsorption.