Synthesis of Al-doped Li2ZrO3 via oxalic acid sol-gel method for CO2 capture in high-temperature fixed-bed reactors

In this study, lithium zirconate (Li2ZrO3)-based materials with varying Al doping levels were synthesized via an oxalic acid sol-gel method, and their CO2 capture performance was evaluated in a high-temperature fixed-bed reactor. The findings revealed that the CO2 capture performance improved notably, rising from 1.43 mmol/g to 2.05 mmol/g, as the Al doping concentration was elevated. Moreover, the Al-doped Li2ZrO3 exhibited excellent cyclic stability, maintaining over 90 % of its initial CO2 capture capacity after 10 sorption/regeneration cycles at 600 degrees C. The synthesized samples were systematically analyzed through multiple advanced characterization techniques. The findings confirmed that oxygen vacancies (OVs) generated during the Al3+-induced substitution of Zr4+ not only enhance CO2 chemical sorption but also accelerate surface reaction kinetics by facilitating the migration of oxygen ions and lithium cations during the carbonate formation stage. The kinetic fitting results indicated that the Avrami model could well describe the sorption process (R2 = 0.9951). Reaction kinetic analysis revealed that indicated that the CO2 sorption process was driven by a combination of physical sorption and chemical reaction mechanisms. This study provides important theoretical foundations and experimental support for the application of Li2ZrO3-based materials in carbon dioxide capture.