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 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 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.

Keywords

CO₂ capture / Li₂ZrO₃ / K-doped Li₂ZrO₃ / citrate / starch / freeze-drying technique

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