Binding energies for alkane molecules on a carbon surface from gas–solid chromatography and molecular mechanics

Comparison of gas–solid chromatography and MM2 force field molecular binding energies for greenhouse gases on a carbonaceous surface

“…In several prior studies of gas-solid interactions, we found the standard augmented MM2 parameters developed by Allinger [11,12] to be suitable to estimate the binding energies of organic molecules interacting with various model carbon surfaces [13][14][15][16]. The adsorption of neutral molecules on a carbon surface is dominated by dispersive van der Waals (VDW) forces.…”

“…The adsorption of neutral molecules on a carbon surface is dominated by dispersive van der Waals (VDW) forces. In previous studies [13][14][15][16] molecule-surface steric energy differences for an adsorbate molecule adjacent to or far from a model adsorbent surface were used to estimate the energy of adsorption or binding energy. Although force field calculations do not reference electronic behavior, they have been widely used for determining minimum energy, and optimized molecular geometries [17].…”

“…Although force field calculations do not reference electronic behavior, they have been widely used for determining minimum energy, and optimized molecular geometries [17]. For the carbon surfaces we have studied and where binding energies have been determined from gas-solid chromatography are available from thermal programmed desorption (TPD), there has been a good correlation between experimental, E * , and calculated, Ecal * , binding energy values [13][14][15][16].…”

“…In our prior work MM2 parameters with no modifications have been found to be suitable to create models of smooth [15], porous [13], and rough [14,16] carbon surfaces, and compute moleculesurface binding energies, Ecal * , that correlated well with experimental binding energies, E * , found from either van't Hoff plots of ln B 2s versus 1/T or published TPD experiments. In the work presented here, the surface model [14,16] previously used to represent molecule-Carbopack B surface interactions for linear alkanes, branched alkanes, ethers, cyclic alkanes, and halogenated hydrocarbons is applied to a new set of eight molecules including: carbon dioxide (CO 2 ); tetrafluoromethane (CF 4 ); hexafluoroethane (C 2 F 6 ); 1,1-difluoroethane (C 2 H 4 F 2 ); 1-chloro-1,1-difluoroethane (C 2 H 3 ClF 2 ); dichlorodifluoromethane (CCl 2 F 2 ); trichlorofluoromethane (CCl 3 F); and 1,1,1-trichloroethane (C 2 H 3 Cl 3 ).…”

“…In the work presented here, the surface model [14,16] previously used to represent molecule-Carbopack B surface interactions for linear alkanes, branched alkanes, ethers, cyclic alkanes, and halogenated hydrocarbons is applied to a new set of eight molecules including: carbon dioxide (CO 2 ); tetrafluoromethane (CF 4 ); hexafluoroethane (C 2 F 6 ); 1,1-difluoroethane (C 2 H 4 F 2 ); 1-chloro-1,1-difluoroethane (C 2 H 3 ClF 2 ); dichlorodifluoromethane (CCl 2 F 2 ); trichlorofluoromethane (CCl 3 F); and 1,1,1-trichloroethane (C 2 H 3 Cl 3 ). This set of eight molecules is combined with two prior sets that included linear alkanes, branched alkanes, ethers, cyclic alkanes, and halogenated hydrocarbons for a total of 36 different E * and Ecal * data pairs comprised of 33 different molecules with three repeated molecules.…”