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 (CaCO3/Ce(OH)CO3) @Ce(OH)CO3 precursors by titrating Ca2+ and Ce3+ into aqueous CO2 storage material (CO2SM) solution simultaneously without adding any templating agents or surfactants. After calcination at 900 degrees C, the novel core-shell type (CaO/CeO2)@CeO2 composite adsorbent with the strong stability of adsorption cycle was syn-thesized. The effects of Ca/Ce doping ratio, CO2SM dosage, drop rate and temperature conditions on the CO2 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 CO2 capture performance during the calcium cycle, and it mainly consisted of CaO and CeO2. The CO2 adsorption amount still maintained at about 430 mg/g after 15 cycles under the adsorption-desorption conditions at 750 degrees C and 900 degrees C. (CaO/CeO2)@CeO2 composite adsorbent is a core-shell structure with CeO2 as the shell and CaO/CeO2 as the liner, in which CeO2 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 CeO2, it can also promote the ion migration during the carbonation process, thus maintaining the adsorption activity. Density functional theory (DFT) cal-culations successfully explain why CeO2 can be used as an inert dopant to promote the adsorption of CO2. After that, the synthesis mechanism of core-shell adsorbent and the reaction mechanism of CO2 adsorption are pro-posed in conjunction with the series characterization. This work provides a new strategy for the efficient syn-thesis of Ca-based adsorbents with special morphology and a new idea for CO2 capture.