Al-Stabilized Double-Shelled Hollow CaO-Based Microspheres with Superior CO2 Adsorption Performance

Abstract

Novel, double-shelled hollow Al-stabilized CaO-based microspheres were successfully prepared through a facile, green method using carbonaceous microspheres as sacrificial templates. Both the morphological and adsorption performance differences, between employing organic and inorganic calcium salt as calcium precursors, to fabricate the double-shelled hollow microspheres were exhibited. Derived from calcium acetate, the Al-stabilized double-shelled hollow microspheres with denser shells showed excellent stability. This was ascribed to the shells that were composed of small CaCO3 nanocrystallite (grain size of <50 nm) and homogeneously distributed stabilizer, Al2O3. Well-spherical, porous hollow structures facilitated CO2 diffusion and buffered mechanical stresses generated by volume change during the calcium looping. The sorbent, CaA40Al1, exhibited a favorable high-temperature CO2 adsorption performance with the capacity of 0.40 g of CO2/g of ads over 60 carbonation/calcination cycles.