CeO_2掺杂对CaO基吸收剂CO_2捕获性能的影响

以P123作为软模板剂,通过均相沉淀法制备了CeO_2掺杂的CaO基吸收剂,研究了CeO_2掺杂对CO_2捕获的影响。结果表明,CeO_2掺杂可促进表面氧物种的生成,从而促进CaO与CO_2的碳酸化反应。CaO-CeO_2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CeO_2中晶格氧的逸出,以及氧空位和O~(2-)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CeO_2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,CeO_2的掺杂有利于CaO的分散,进而减缓CaO烧结。CeO_2掺杂的吸收剂在碳酸化/煅烧循环中表现出良好的CO_2捕获性能和循环稳定性。

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

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 O^2-. E_a is tested to be 28.1 kJ/mol for the carbonation reaction of pure CaO sorbent, while E_a 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.