Promotion effect of Ce doping on MgO-based adsorbents for CO2 adsorption performances

Abstract

This paper presented the effect of Ce doping on the structure, morphology and CO2 adsorption performances of MgO-based adsorbents. Nano MgO-based adsorbents were synthesized by citric acid complexation method using Mg(NO3)2·6H2O and Ce(NO3)3·6H2O as the precursors, and characterized by XRD, SEM, N2 adsorption/desorption and FT-IR techniques, respectively. The results demonstrated that with Ce incorporation, the crystal sizes of the adsorbents were obviously reduced, and a large number of micropores and mesopores were formed. The CO2 adsorption of the samples was carried out on a thermogravimetric analyzer, and the adsorption data were fitted by the first-order kinetic equation, the pseudo second-order kinetic equation and the intra-particle diffusion model, respectively. It can be concluded after Ce doping, the adsorption capacity of the adsorbent was greatly improved, due to good dispersity of MgO particles and well-developed porosity, and the increase of the surface reaction rate could be attributed to the increase of BET surface area and the alkaline sites of the Ce-incorporated adsorbents, while the increase of the rate in the diffusion stage was caused by the formation of the porous structure. Therefore, the smaller the crystal size of MgO, the more favorable it was for CO2 capture. This work provided the inspiration of MgO-based adsorbent for improving CO2 adsorption.