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

该项目的目的是进行一项研究，以确定多孔介质中的约束对化学反应的影响。 虽然在理解多孔介质中的约束对物理性质的影响方面取得了很大进展，但还没有关于化学效应的基本理论或分子模拟工作，特别是化学反应平衡。 直接的实验研究是复杂的困难，在测量组成的限制相，并在区分平衡速率限制。 限制可能对反应的产率有实质性影响，其中由于孔体积密度增加或孔壁附近的强选择性效应，摩尔数发生净变化;分子取向也可能起作用。 然而，这些影响的程度目前尚不清楚。 一个目标是阐明限制对化学平衡的影响的基本原理。 选择用于研究的反应是一氧化氮二聚反应和一氧化氮还原为氮气和氧气。 这些反应将在活性炭和碳纳米管中进行。 将进行反应性正则蒙特卡罗模拟，以研究孔径、孔形状、温度和压力对反应产率、组成分布和反应热的影响。 多孔材料被广泛用于化学，石油，天然气和制药工业作为催化剂和化学过程，如吸附分离，干燥和去除气体和液体流中的污染物，在这项研究中确定的基本原理可能在这些领域的应用。

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.