Experiments and mechanism of kinetics/stability of CO2 capture by Ce/Zr carrier-loaded MgO-based adsorbents

Abstract

Magnesium oxide (MgO) has demonstrated tremendous potential in carbon capture and utilization (CCU) technology. However, it still faces limitations such as low adsorption kinetics and poor stability. In this study, the sol–gel combustion method was employed to synthesize MgO/molten salt composite adsorbents supported on Ce/Zr carriers. The investigation focused on the influence of carrier composition on adsorption performance. The experimental results revealed that as the loading of CeO2 increased, the adsorbent materials transitioned from a porous foam-like connectivity to the formation of a shell structure. Interestingly, the low content of CeO2 facilitated enhanced CO2 diffusion and hindered the aggregation of MgO aggregates, resulting in improved adsorption performance. Furthermore, the adsorbents supported on ZrO2 demonstrated excellent particle size stability and cyclic stability due to the higher Tamman temperature of ZrO2 and the uniform dispersion of MgO on ZrO2. Utilizing density functional theory, a surface configuration of CeO2/ZrO2 catalyst-modified MgO (100) was constructed to elucidate the enhanced adsorption mechanism of CeO2/ZrO2 on MgO. The cluster model revealed a strong interaction between cluster O atoms and CO2 molecules, enhancing the charge transfer capability of the MgO surface towards CO2 and consequently strengthening its adsorption performance.