Small Grant for Exploratory Research: Effect of Confinement on Reaction Equilibrium in Porous Materials

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The aim of this project is to carry out a study to determine the effects of confinement in porous media on chemical reactions. Although there has been much progress in understanding the effects of confinement in porous media on physical properties, there has been no fundamental theoretical or molecular simulation work on chemical effects, particularly on chemical reaction equilibrium. Direct experimental investigations are complicated by difficulties in measuring compositions in the confined phase and in differentiating equilibrium from rate limitations. Confinement may have a substantial effect on the yields of reactions in which there is a net change in the number of moles because of increased density in pore volume or strong selectivity effects near the pore walls; molecular orientation may also play a role. However, the magnitude of these effects is currently unknown. A goal is to elucidate the fundamental principles that underlie confinement effects on chemical equilibrium. The reactions chosen for study are the nitric oxide dimerization reaction and the reduction of nitric oxide to nitrogen and oxygen. These reactions will be carried out in activated carbons and in carbon nanotubes. Reactive canonical Monte Carlo simulations will be performed to investigate the effects of pore size, pore shape, temperature, and pressure on the reaction yield, composition profiles and heats of reaction. Porous materials are widely used in chemical, oil, gas, and pharmaceutical industries as catalysts and in chemical processes such as adsorption separations, drying, and removal of pollutants from gas and liquid streams; the fundamental principals determined in this study may have application in these areas.