Theoretical Studies of Near-Critical Fluids in Dilute Porous Media

Andrea Liu获得了理论与计算化学项目的早期职业发展奖，主要研究近临界流体（如气液系统或二元液体混合物）的平衡相行为和扩散输运，这些流体被限制在稀释多孔介质（如硅胶）中。一般来说，近临界流体在多孔介质中的行为是一个极其困难的理论问题，因为介质表面强烈倾向于流体的一个相，并且介质的结构是高度无序的。Liu使用的方法侧重于流体与表面之间的强相互作用；以前的理论工作假设这种相互作用是微弱的，无序是主要因素。该建议的重点是一个模型的限制介质作为一个简单的周期网络的圆柱形股，刘已经解决了平均场近似。本文在此基础上，采用解析和数值技术相结合的方法，研究了凝胶结构中临界波动和长波长失序的影响，以及非平衡行为。这种方法最有希望分离出表面相互作用和介质几何无序的影响，从而确定它们对平衡和非平衡行为的相对重要性。拟议的教育计划以有效的科学传播为中心。目的是为非专业学生揭开科学的神秘面纱，让他们相信化学是日常生活中重要而有趣的一部分，并教专业学生和研究生如何更有效地交流他们的工作。稀多孔介质中接近临界的流体，如Liu所研究的，是更现实的多孔介质中更一般的多相流体的模型。具有工业重要性的应用范围从多孔床的催化，到在多孔玻璃中储存液体废物和液体燃料，再到从砂岩等多孔介质中提取液体（如石油）。对多孔介质中输运的理论认识的改进可能会对这些战略领域产生重大影响。

Andrea Liu is supported by a Faculty Early Career Development Award from the Theoretical and Computational Chemistry Program to study equilibrium phase behavior and diffusive transport in near-critical fluids, such as vapor-liquid systems or binary liquid mixtures, confined in dilute porous media such as silica gels. In general, the behavior of a near-critical fluid in a porous medium is an extremely difficult theoretical problem, because the surface of the medium strongly prefers one phase of the fluid and because the structure of the medium is highly disordered. The approach used by Liu focuses on the strong interaction between the fluid and the surface; previous theoretical work has assumed that the interaction is weak and that disorder is the dominant factor. The keystone of the proposal is a model of the confining medium as a simple periodic network of cylindrical strands, which Liu has solved within the mean-field approximation. The proposed work builds on this basic model by using a coordinated combination of analytic and numerical techniques to investigate the effects of critical fluctuations and long-wavelength disorder in the gel structure, as well as the nonequilibrium behavior. This approach represents the best hope of isolating the effects of surface interactions and of disorder in the geometry of the medium in order to determine their relative importance for equilibrium and nonequilibrium behavior. The proposed education plan is centered around effective scientific communication. The objectives are to demystify science for non-majors and to convince them that chemistry is an important and interesting part of daily life, and to teach majors and graduate students how to communicate their work more effectively. Nearly critical fluids in dilute porous media, such as those studied by Liu, are models for more general multiphase fluids in more realistic porous media. Applications that are of industrial importance range from catalysis in porous beds, to storage of liquid wastes and liquid fuels in porous glasses, to the extraction of liquids such as oil from porous media like sandstone. An improved theoretical understanding of transport in porous media could have a significant impact in several of these strategic areas.