Study on CO2 sorption performance and sorption kinetics of Ce- and Zr-doped CaO-based sorbents

In this work, a series of Ce-doped, Zr-doped and Zr-Ce co-doped CaO-based sorbents were prepared by the sol-gel method. The multi-cycle CO2 sorption performance test under mild conditions showed that the Zr-doped sorbents had better stability than the Ce-doped sorbents. This is because CaZrO3 had a higher Tammann temperature than CeO2, which could inhibit the growth and agglomeration of sorbent particles more effectively. However, compared with the Zr-doped sorbents, the Ce-doped sorbents had a higher CO2 sorption rate at cycle 1. This is because CeO2 has abundant oxygen vacancies to facilitate the mobility of O2−, thus promoting the carbonation reaction. It is worth noting that the Zr-Ce co-doped CaO-based sorbents combined the advantages of high Tammann temperature and oxygen vacancy of two inert materials, so it had a more balanced CO2 sorption performance. Since higher calcination temperature (950 °C) and CO2 concentration (90 vol.%) accelerated the sintering of the sorbents, the selected sorbents showed faster deactivation​​ under severe conditions. SGZr10 exhibited excellent CO2 capture performance under both mild and severe conditions.