CO2 capture performance of ZrO2-doped Na2CO3/γ-Al2O3 adsorbent.

Sodium-based adsorbents (Na2CO3/γ-Al2O3) exhibit significant potential for commercial utilization in CO2 capture. Nevertheless, the requirement for high desorption temperatures poses challenges in terms of the high-quality heat needed for desorption. This study integrated ZrO2 doping into a sodium-based adsorbent to enhance its CO2 capture performance and lower its desorption temperature. The research investigated the CO2 adsorption capacity, reaction rate, and desorption characteristics of the ZrO2-doped Na2CO3/γ-Al2O3 adsorbents in detail. Additionally, the catalytic mechanism of ZrO2 was elucidated through Density Functional Theory calculations. The results showed that ZrO2 doping increased the adsorption rate and capacity of the adsorbent and reduced the desorption energy consumption. Desorption reaction activation energy reduced to 44.8 kJ/mol. The adsorbent doped with 3 wt.% ZrO2 demonstrated the highest adsorption capacity and rate under optimal conditions, with a reaction temperature of 45 ℃, an adsorption capacity of 1.66 mmol/g, and a carbon conversion rate of 80.2 %. ZrO2 acted as a catalyst, enhancing CO2 and H2O adsorption, and facilitated CO2 desorption in the sodium-based adsorbent by forming [ZrO(OH)]+ and OH- through H2O adsorption activation. The lower energy barrier (0.17 eV) for the dissociative adsorption pathway of H2O molecules on the ZrO2 surface further supported the role of ZrO2 in enhancing the overall adsorption performance of the adsorbent in the carbon capture process. Ultimately, the ZrO2-doped Na2CO3/γ-Al2O3 adsorbent was identified as having low desorption energy consumption, high adsorption capacity, and rate, offering potential cost reductions in CO2 capture and representing a promising adsorbent for this application.