Fabrication of MgO@AC porous composite for CO2 capture by a solid-state heat dispersion approach

Activated carbon (AC) supported MgO (MgO@AC) for CO2 capture has been facilely prepared with Mg(NO3)2 as precursor by a solid-state heat dispersion method. The prepared MgO@AC adsorbents with different magnesium loadings were characterized by X-ray diffraction (XRD), N2 adsorption/desorption and scanning electron microscope (SEM), and were investigated for the CO2 adsorption capacity, CO2 adsorption selectivity and cyclic stability. The characterization results reveal that the precursor of Mg(NO3)2 can be highly dispersed on the surfaces of the AC support and converted to MgO during the activation process at high temperatures. The experimental results show that the MgO@AC adsorbent with the MgO loadings of 5 mmol/g AC support achieves a high CO2 adsorption capacity, high CO2/N2 adsorption selectivity and excellent reversibility. Its good adsorption performance and facile fabrication process make it a promising adsorbent for CO2 capture from flue gases. In addition, the isosteric heat of CO2 adsorption on this adsorbent was calculated from the CO2 adsorption equilibrium isotherms at different temperatures using the Clausius–Clapeyron equation, the values are in the range of 45.4–20.1 kJ/mol.