GOALI: Fundamental Studies of Transport of Mixtures in Microporous Membranes under Supercritical Conditions

摘要本项目是一个学术/工业合作研究项目（GOALI），旨在研究超临界碳氢化合物/CO2混合物在微孔碳分子筛膜中的传输。研究将分两部分进行：（1）膜的制备和实验表征沿着合成过程中其结构演变的计算机建模;（2）膜内超临界混合物的吸附和传输的测量和同步计算机模拟。 所研究的系统是由CO2和一种或多种以下烃、丁烷、异丁烷、苯和甲苯组成的超临界混合物。 选择这些烃类来代表典型的脂肪族和芳香族化合物，并允许探索分子形状等因素。 非平衡巨正则分子动力学（NEGCMD）模拟技术被用来研究这些混合物在微孔材料中的输运。 分子计算的目的是将膜的分子结构与实验观察到的传输特性和分离效率相关联。 长期目标是实现分子筛和催化膜反应器的改进材料的可靠工程和设计。 这些研究的结果将有助于应用程序，如超临界CO2的吸附剂的再生和超临界条件下的膜的使用。 碳分子筛膜能够承受与超临界条件相关的高压和高温。 它们可以制备成具有良好控制的孔隙率和孔径以及非常窄的孔径分布。 了解这些材料的能力，以影响基于膜内分子流动性的差异分离超临界混合物的因素，将促进它们在去除水，污泥，土壤，废催化剂和吸附剂，如颗粒活性炭中的各种污染物的使用。 与通常用于从超临界溶剂中分离溶质的能量密集型膨胀/再压缩循环相比，从超临界二氧化碳中连续去除溶质的能力将显著降低操作成本。

ABSTRACT This project is a collaborative academic/industrial research (GOALI) project to investigate the transport of supercritical hydrocarbon/CO2 mixtures in microporous carbon molecular-sieve membranes. The study will proceed in two parts: (1) preparation and experimental characterization of the membrane along with computational modeling of the evolution of its structure during synthesis; and (2) measurement and simultaneous computer simulation of the sorption and transport of supercritical mixtures within the membranes. The systems under study are supercritical mixtures composed of CO2 and one or more of the following hydrocarbons, butane, isobutane, benzene, and toluene. These hydrocarbons were selected to represent typical aliphatic and aromatic compounds and to permit exploration of factors such as molecular shape. Non-equilibrium grand canonical molecular dynamics (NEGCMD) simulation techniques are being used to study the transport of these mixtures in microporous materials. The objective of the molecular calculations is to relate and correlate the membrane's molecular structure with experimentally observed transport properties and separation efficacy. The long-term goal is to achieve reliable engineering and design of improved materials for molecular sieves and catalytic-membrane reactors. The results of these studies will contribute to applications such as the regeneration of adsorbents by supercritical CO2 and the use of membranes under supercritical conditions. Carbon molecular- sieve membranes are capable of withstanding the high pressures and temperatures associated with supercritical conditions. They can be prepared with well-controlled porosity and pore size and a very narrow pore-size distribution. Understanding the factors determining the ability of these materials to effect separations of supercritical mixtures based on differences in molecular mobility within the membranes will promote their use in the removal of various contaminants from water, sludges, soils, spent catalysts, and adsorbents like granular activated carbon. The ability to remove solutes continuously from supercritical carbon dioxide would produce significant reductions in operating costs compared with the energy-intensive expansion/re-compression cycle normally used to separate solutes from supercritical solvents.