Effect of micropores on CO2 capture in ordered mesoporous CMK-3 carbon at atmospheric pressure

This paper presents an investigation of CO2 capture ability of ordered carbon (CMK-3) composed of a two-dimensional hexagonal array of turbostratic carbon rods of 19.7 nm and 8.7 nm in diameter with interstitial mesopores and non-restricted micropores in the rods at atmospheric pressure. The CMK-3 carbon had a mesopore mean inner diameter of 3.42 nm and a microporous structure with modus of pore diameter of 1.30 nm. Despite the fact that the mesopores did not directly take part in CO2 adsorption at atmospheric pressure, the carbon material exhibited good performance in CO2 capture, adsorbing 1.70 mmol g−1 and 1.07 mmol g−1 in the micropores at 293 and 323 K, respectively. The open mesoporous channel structure with regular architecture provided easy accessibility of the micropores in the carbon walls that formed the structure of CMK-3 carbon. Enhancement of accessibility improved the molecular transport of CO2, providing advantageous kinetics compared to purely microporous materials. The adsorption rate obtained from kinetics studies were decreasing with gas pressure increase in the system and were increasing with temperature increase. The ordered mesoporous-microporous carbon structure allowed excellent reversibility, regeneration ability and high selectivity of CO2 over N2 molecules.