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 °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.