The Mn-promoted double-shelled CaCO3 hollow microspheres as high efficient CO2 adsorbents

Novel Mn-promoted double-shelled hollow CaCO3 microspheres were successfully synthesized by a versatile template method using carbon microspheres as sacrificial templates, achieving the controllable adjustment of Ca-Mn molar ratio, microsphere size and shell thickness. The Mn-promoted hollow CaCO3 microspheres with self-supported double shells effectively handled the collapsing problem led by the continuous volume variations, of which the adsorption performance notably outperformed that of the pure CaCO3 counterpart. The uniformly distributed Mn considerably enhanced structural stability of the double-shelled hollow microspheres and reduced the crystalline size of CaCO3. Furthermore, the existence of Mn promoted the ability of donating electrons of CaO to CO2 and was presumably to bring about oxygen vacancies. The sorbent Ca12Mn1-500 exhibited an initial CO2 adsorption capacity of 0.62 g-CO2/g-ads and a final one of 0.53 g-CO2/g-ads after 25 adsorption-desorption cycles.