A novel (CaO/CeO2)@CeO2 composite adsorbent based on microinjection titration-calcination strategy for CO2 adsorption

A simultaneous titration-calcination strategy was proposed to synthesize core–shell type (CaCO 3 /Ce(OH)CO 3 )@Ce(OH)CO 3 precursors by titrating Ca 2+ and Ce 3+ into aqueous CO 2 storage material (CO 2 SM) solution simultaneously without adding any templating agents or surfactants. After calcination at 900 °C, the novel core–shell type (CaO/CeO 2 )@CeO 2 composite adsorbent with the strong stability of adsorption cycle was synthesized. The effects of Ca/Ce doping ratio, CO 2 SM dosage, drop rate and temperature conditions on the CO 2 adsorption performance on the composite adsorbent during the calcium cycle were investigated. The synthetic adsorbent with a Ca/Ce doping ratio of 24: 1 had the strongest CO 2 capture performance during the calcium cycle, and it mainly consisted of CaO and CeO 2 . The CO 2 adsorption amount still maintained at about 430 mg/g after 15 cycles under the adsorption–desorption conditions at 750 °C and 900 °C. (CaO/CeO 2 )@CeO 2 composite adsorbent is a core–shell structure with CeO 2 as the shell and CaO/CeO 2 as the liner, in which CeO 2 is uniformly dispersed in CaO pore channels, which gives the adsorbent a stable pore structure and enhances the anti-sintering performance of Ca-based adsorbent. Due to the special property of CeO 2 , it can also promote the ion migration during the carbonation process, thus maintaining the adsorption activity. Density functional theory (DFT) calculations successfully explain why CeO 2 can be used as an inert dopant to promote the adsorption of CO 2 . After that, the synthesis mechanism of core–shell adsorbent and the reaction mechanism of CO 2 adsorption are proposed in conjunction with the series characterization. This work provides a new strategy for the efficient synthesis of Ca-based adsorbents with special morphology and a new idea for CO 2 capture.