Molecular simulation of carbon dioxide adsorption in chemically and structurally heterogeneous porous carbons

Abstract

Capture of carbon dioxide from fossil fuel power plants via adsorption and sequestration of carbon dioxide in unmineable coal seams are achievable near-term methods of reducing atmospheric emissions of this greenhouse gas. To investigate the influence of surface heterogeneity upon predicted adsorption behavior in activated carbons and coal, isotherms were generated via grand canonical Monte Carlo simulation for CO 2 adsorption in slit-shaped pores with underlying graphitic structure and several variations of chemical heterogeneity (oxygen and hydrogen content), pore width, and surface functional group orientation. Adsorption generally increased with increasing surface oxygen content, although exceptions to this trend were observed on structurally heterogeneous surfaces with holes or furrows that yield strongly adsorbing preferred binding sites. Among the heterogeneous pore structures investigated, those with coal-like surfaces adsorbed carbon dioxide more strongly than planar, homogeneous graphitic slit pores of comparable width. Electrostatic adsorbate–adsorbent interactions significantly influenced adsorption onto model surfaces. © 2006 American Institute of Chemical Engineers Environ Prog, 25: 343–354, 2006