Thermodynamic and kinetic analyses of the CO₂ chemisorption mechanism on Na₂TiO₃: Experimental and theoretical evidences

Sodium metatitanate (Na₂TiO₃) was successfully synthesized via a solid-state reaction. The Na₂TiO₃ structure and microstructure were characterized using X-ray diffraction, scanning and transmission electron microscopy, and N₂ adsorption. Then, the CO₂ chemisorption mechanism on Na₂TiO ₃ was systematically analyzed to determine the influence of temperature. The CO₂ chemisorption capacity of Na₂TiO ₃ was evaluated both dynamically and isothermally, and the products were reanalyzed to elucidate the Na₂TiO₃-CO₂ reaction mechanism. Different chemical species (Na₂CO₃, Na₂O, and Na₄Ti₅O₁₂ or Na ₁₆Ti₁₀O₂₈) were identified during the CO ₂ capture process in Na₂TiO₃. In addition, some CO₂ chemisorption kinetic parameters were determined. The ΔH^‡ was found to be 140.9 kJ/mol, to the Na ₂TiO₃-CO₂ system, between 600 and 780 °C. Results evidenced that CO₂ chemisorption on Na₂TiO ₃ highly depends on the reaction temperature. Furthermore, the experiments were theoretically supported by different thermodynamic calculations. The calculated thermodynamic properties of CO₂ capture reactions by (Na₂TiO₃, Na₄Ti₅O ₁₂, and Na₁₆Ti₁₀O₂₈) sodium titanates were fully investigated.