DENSITY FUNCTIONAL THEORY CALCULATIONS OF CO2 AND CH4 INTERACTIONS WITH CLAY SURFACES

摘要

The use of supercritical carbon dioxide (CO ) as a fracturing fluid for enhanced gas recovery is receiving increased attention as it could accomplish the dual purpose of sequestering CO2 in mineral formations, and recovering CH4 as a source of energy. Isotherms for CO2 and CH4 adsorbed to mineral surfaces have been determined experimentally and are available in the literature . While these experimental isotherms allow one to infer the affinity of the adsorbates for the substrates, computational chemistry can provide a molecular level interpretation of the interactions between CO2 and CH4 and the substrate, necessary for the development of first-principle models of these complex systems. In this work the adsorption of these molecules is explored with two model substrates, a Na-montmorillonite with surface charge, and kaolinite.