Comparison study on strategies to prepare nanocrystalline Li2ZrO3-based absorbents for CO2 capture at high temperatures

A comparison study has been conducted on the strategies for synthesizing nanocrystalline Li 2 ZrO 3 and Kdoped Li 2 ZrO 3 absorbents for CO 2 capture at high temperatures, including solid-state and liquid-phase methods, citrate route, and starch-assisted sol-gel method combined with freeze-drying technique. The absorption properties, including uptake rate and absorption capacity, of synthesized absorbents were investigated by thermogravimetric analysis (TGA) at different CO 2 partial pressures. The nanosized Li 2 ZrO 3 crystals synthesized by the citrate route exhibit a faster uptake and a higher, nearly stoichiometric absorption capacity than those synthesized by the solid-state and liquid-phase methods. The doping of K into Li 2 ZrO 3 can significantly improve the uptake rate of CO 2 , especially at low CO 2 partial pressures. For the synthesis of K-doped Li 2 ZrO 3 , the citrate route has poor reproducibility and scalability, whereas the starch-assisted sol-gel method combined with freeze-drying technique is reproducible and easily scaled up, and the thus synthesized absorbents possess excellent CO 2 capture properties.