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.

Key words： CO₂ capture; Li₂ZrO₃; K-doped Li₂ZrO₃; citrate; starch; freeze-drying technique

Acknowledgements

The financial supports from the National Basic Research Program of China (2009CB626607), the National Natural Science Foundation of China (21036006), the Program for Changjiang Scholars and Innovative Research Team in Chinese Universities (IRT0980), and the Program for Zhejiang Leading Team of Science and Technology Innovation (2011R09020-05) are gratefully acknowledged.

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