High Temperature CO2 Capture on Novel Yb2O3-Supported CaO-Based Sorbents

Incorporation of CaO in inert solid support has been identified as an effective approach to improve the cyclic CO2 capture performance for CaO-based sorbents. In this work, Yb2O3-supported CaO-based sorbents were fabricated via the wet mixing technique. Elemental dispersion observed by FSEM-EDS showed that the ultrafine active species of CaO particles was finely separated by Yb2O3. Different amounts of Yb2O3 were introduced and 10-15 wt% was found to be the optimal content range for the support to function as the metal skeleton. In comparison with pure CaO, the improved CO2 capture performance was observed for CaYb10 over prolonged carbonation-calcination cycles under a severe test condition. This improvement could be ascribed to the enriched macropores within 50-100 nm, which was identified by the N-2 adsorption-desorption analysis. In addition, the microstructure of the synthetic sorbent (analyzed through TEM images) indicated that CaO particles of similar to 160 nm were formed with the Yb2O3 nanocrystallines (similar to 15-25 nm) adhered to the surface functioning as physical barriers and as a result, the sintering was effectively retarded. Generally, the enhanced cyclic CO2 capture performance and the promoted sintering-resistant property of Yb2O3-supported CaO-based sorbents made Yb2O3 a promising inert solid support.