CO₂ Capture Performance of Ca-Ni-Ce Composite Materials

CO₂ is the predominant greenhouse gas in the atmosphere, and the development of efficient CO₂ capture and utilization technologies is crucial for achieving carbon peaking and carbon neutrality. Calcium-based adsorbents have attracted extensive attention because of their excellent CO₂ capture capability, while nickel-based catalysts are widely used in developing Ca-Ni bifunctional materials due to their outstanding catalytic performance. Doping with Ce-containing promoters can further improve the efficiency and stability of these materials. However, commonly used sorbents still suffer from low efficiency, high cost, and poor sintering resistance. In this work, a Ca-Ni-Ce composite system was investigated. A series of CaO-Ni-CeO₂ composite samples with different CeO₂ loadings were synthesized via a citrate complexation method, and their physicochemical properties were characterized by XRD, SEM, etc. Thermogravimetric analysis was employed to evaluate the CO₂ uptake of the samples under cyclical conditions, and the effects of CO₂ concentration and carbonation temperature on their capture performance were systematically investigated. The results indicate that doping with an appropriate amount of CeO₂ can effectively enhance the CO₂ capture performance of the composites. The optimal CeO₂ content maintains sufficient active sites while effectively inhibiting sintering, thereby significantly improving the stability of the sorbent over multiple cycles. Among the four groups of samples, the Ni-Ca₁₀Ce sample exhibited the best sintering resistance and CO₂ capture efficiency, with an average CO₂ uptake of 0.46 g·g⁻¹ _sor and an average carbonation conversion of 94.35% over 20 thermogravimetric cycles. Increasing CO₂ concentration promotes the carbonation reaction. Specifically, the adsorption efficiency improved significantly as the concentration rose up to 20 vol.%, beyond which further concentration increases yielded no substantial improvement due to the near-complete saturation of active sites. Additionally, a moderate increase in reaction temperature promotes the chemisorption of CO₂ molecules on the CaO surface, enhancing the surface reaction rate by reducing the activation energy. Therefore, 650 °C was identified as the optimal temperature to balance material activity and adsorption efficiency. Considering long-term stability and economic viability, the temperature should not exceed 700 °C to prevent material sintering and attrition. This study provides a technical reference for the preparation and optimization of new CO₂ capture materials and offers an effective strategy for industrial carbon neutrality.