Investigation on a novel CaO–Y2O3 sorbent for efficient CO2 mitigation

• Y2O3-stabilized CaO sorbents were synthesized for high-temperature CO2 capture.
• Carbonation kinetics was greatly improved by Y2O3 introduction.
• The effect of calcination conditions on sorbent structure was investigated.
• The sorbent holds good potential for practical application.

Different amounts of Y2O3 were incorporated into CaO through a sol–gel combustion method and compared with two naturally occurring sorbent and CaO derived from calcium acetate on CO2 capture performance. XRD, SEM, TEM and N2 adsorption results revealed that homogeneously dispersed Y2O3 nanoparticles notably improved the sorbent morphology, and therefore the capture performance. The carbonation rate in the fast stage was greatly enhanced via Y2O3 addition and a linear relationship was established between the maximum carbonation rate and the volume of pores with diameters less than 220 nm. The sorbent containing 20 wt% Y2O3 presented excellent cyclic CO2 capture capacity as well as stability. After 10 cycles it absorbed 0.57 g CO2/g sorbent under mild conditions and still 0.49 g CO2/g sorbent under realistic conditions, respectively. Finally, calcination conditions significantly influenced the sorption performance and sorbent structure. Combined with pore size distribution measurement, enhanced sintering and reactivation, two counteractive roles brought by CO2 addition during calcination, were elucidated.