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

这个项目的目的是进行一项研究，以确定在多孔介质中限制对化学反应的影响。虽然在了解多孔介质中约束对物理性质的影响方面取得了很大进展，但在化学效应，特别是化学反应平衡方面，还没有基本的理论或分子模拟工作。直接的实验研究由于在限制相中测量成分和区分平衡与速率限制方面的困难而变得复杂。由于孔体积的密度增加或孔壁附近的强选择性效应，使得摩尔数的净变化，限制可能对反应的产率有实质性的影响；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。目标是阐明约束效应对化学平衡的基本原理。选择的反应是一氧化氮二聚化反应和一氧化氮还原为氮和氧。这些反应将在活性炭和碳纳米管中进行。反应规范蒙特卡罗模拟将进行研究孔径，孔的形状，温度和压力对反应产率，组成曲线和反应热的影响。多孔材料广泛应用于化工、石油、天然气和制药行业，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；本研究确定的基本原则可应用于这些领域。

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.