Research progress of calcium-based adsorbents for CO₂ capture and anti-sintering modification

As one of the important solid adsorbents for CCUS (CO₂ Capture, Utilization and Storage), the calcium-based adsorbents have attracted wide attention because they can directly capture CO₂ from high-temperature flue gas and have a low cost and good adsorption performance. However, the calcium-based adsorbents are easy to sinter during repeated adsorption-desorption cycles, which will cause a sharp drop in adsorption performance. In this work, the reaction kinetics, thermodynamics and the sintering mechanism of the calcium-based adsorbents were summarized. At the same time, the advantages and limitations of various anti-sintering modification methods were compared and analyzed. The results show that the hydration modification can cause the adsorbent to collapse and obtain a larger surface area. The acid solution modification will generate more gas and small molecules during the preparation process to increase the porosity of the absorbent. Doping modification can promote the adsorption and diffusion of CO₂, and the dopant can be acted as a framework to separate CaO particles. It can be concluded that the doping modification is a relatively promising modification method due to its simple process and good performance; and the use of calcium-containing solid waste for preparation of anti-sintering modified adsorbents has great potential for application.