Porous hollow CaO microsphere synthesized by the template-assisted approach for enhanced CO2 capture

The development of cheap, environmentally friendly adsorbents with high adsorption capacity and good cycle stability is of great significance for reducing excessive CO2 emissions. However, the CaO-based adsorbents with low prices and high theoretical adsorption capacity suffer from serious sintering problems and poor cyclic stability. Herein, we synthesized porous hollow CaO microspheres for enhanced CO2 capture by the template-assisted approach, in which the carbon sphere template with different carbon chain lengths were prepared by hydrothermal method. The interaction between carbon chain lengths, morphologies, and properties of CaO-based adsorbents was systematically investigated. The results show that the porous hollow CaO microsphere prepared with a sucrose carbon template possesses a higher initial CO2 adsorption capacity (15.3 mmol g−1) and better cyclic stability after 20 cycles by reducing the mass transfer length of CO2 and buffering the volume expansion. In addition, the kinetics study reveals that the porous hollow spherical morphology can significantly improve the CO2 adsorption kinetics, especially in the chemical control stage, which provides theoretical guidance for the further understanding of the carbonization process. The systematic study marks the significance of precise tailoring of porous hollow CaO microsphere to achieve the desired performance of CO2 adsorption.