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.