CeO2掺杂对CaO基吸收剂CO2捕获性能的影响

Influence of cerium doping on CO2 capture of CaO-based sorbents

  • 摘要: 以P123作为软模板剂,通过均相沉淀法制备了CeO2掺杂的CaO基吸收剂,研究了CeO2掺杂对CO2捕获的影响。结果表明,CeO2掺杂可促进表面氧物种的生成,从而促进CaO与CO2的碳酸化反应。CaO-CeO2的相互作用一方面促进了从Ca到表面氧物种的电子转移;另一方面,由于部分Ca离子对晶格中Ce离子的取代,晶格的电中性被打破,有利于CeO2中晶格氧的逸出,以及氧空位和O2-的生成。本实验制备的纯CaO吸收剂的碳酸化反应活化能为28.1 kJ/mol,而掺杂CeO2后活化能显著降低,且当Ce/Ca(物质的量比)为0.25时达到最低值10.2 kJ/mol。另外,CeO2的掺杂有利于CaO的分散,进而减缓CaO烧结。CeO2掺杂的吸收剂在碳酸化/煅烧循环中表现出良好的CO2捕获性能和循环稳定性。

     

    Abstract: The CeO2-doped CaO-based sorbent was prepared by the homogeneous precipitation method using P123 as the soft template. The influence of CeO2 doping on the capture of CO2 was investigated. The CeO2 doping can promote the formation of surface oxygen species, and facilitate the carbonation reaction. The interactions in CaO-CeO2 lead to the electrons transfer from Ca to surface oxygen species. Moreover, when Ce ions are substituted by Ca ions, the charge neutrality is destroyed in the CeO2 crystal, which promotes the formation of oxygen vacancies and O2-. Ea is tested to be 28.1 kJ/mol for the carbonation reaction of pure CaO sorbent, while Ea decreases to the minimal value of 10.2 kJ/mol when adding CeO2 to CaO sorbent with a Ce/Ca molar ratio of 0.25. Also, the doping of CeO2 is beneficial to the high dispersion of CaO and prevention of CaO sintering. The Ce-doped sorbents exhibit a superior capture capacity and cyclic stability in carbonation/calcination cycles.

     

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