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

Abstract

A comparison study has been conducted on the strategies for synthesizing nanocrystalline Li2ZrO3 and K- doped Li2ZrO3 absorbents for CO2 capture at high temperatures, including solid-state and liquid-phase meth- ods, 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 thermo- gravimetric analysis (TGA) at different CO2 partial pressures. The nanosized Li2ZrO3 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 Li2ZrO3 can significantly improve the uptake rate of CO2, especially at low CO2 partial pressures. For the synthesis of K-doped Li2ZrO3, 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 CO2 capture properties.