Molecular simulation of CO2 adsorption in micro- and mesoporous carbons with surface heterogeneity

To mitigate and stabilize atmospheric CO2 concentrations, alternate energy sources with zero carbon emissions offer ultimate solutions. However, technologies based on efficient and economic generation of electricity from non-carbonized energy sources are still in development. Therefore, carbon capture combined with sequestration as a component of a greater portfolio of solutions to reduce CO2 emissions may be carried out during our transition from fossil-based resources to renewables or non-carbonized resources. As one of the attractive options, CO2 captured by carbon-based sorbents as well as CO2 sequestration in unmineable coalbeds require a thorough understanding of the adsorption properties in micro- and mesoporous carbon materials. An obstacle is insufficient understanding of the molecular-level mechanisms associated with CO2 adsorption on realistic carbon pore surfaces with chemical heterogeneities and at pressures and temperatures characteristic of the depths of coal in the subsurface. Current fundamental investigations of gas adsorption onto functionalized carbon surfaces involve the characterization of carbon-based samples by experimental methods, understanding of electronic properties of functionalized carbon surfaces by density functional theory, and the thermodynamic property predictions using a Monte Carlo method within the grand canonical ensemble. With the consideration of surface chemistry, CO2 storage capacity estimations in organic matrix of coal and gas shale increase greater than 40% when CO2 is adsorbed in the ultramicropores, and greater than 15% in 2-nm micropores. (C) 2012 Elsevier B.V. All rights reserved.