Modeling Adsorption in Complex Porous Structures: Equilibrium, Hysteresis and Dynamics

Peter A. Monson，马萨诸塞大学阿默斯特分校，“复杂多孔结构中的吸附建模：平衡、滞后和动力学”，这项研究将使用分子模型来理解具有复杂孔隙结构的多孔材料中流体的行为。主要目标是对分子相互作用和多孔材料的结构如何在几个长度尺度上产生特定类型的吸附行为的综合效应有更精确的理解。这种理解是中心的重要应用，如分离和催化，以及在多孔材料表征。动态和平衡建模技术的结合是这个项目的中心特征。计划开展两个互补的研究领域。在第一个领域，PI涉及复杂孔隙结构中吸附/解吸的粗粒度晶格模型。这项工作的目标是建立一个框架来理解吸附测量和多孔材料微观结构之间的关系-特别是在毛细冷凝和滞后状态下。最近的工作表明，粗粒度的晶格模型提供了对迟滞的重要见解，PI试图以几种方式建立在此基础上。在提议的工作中，PI将扩展该方法可以处理的材料范围，包括应用于各种介孔二氧化硅材料，并将该方法应用于汞孔隙学中的入侵/挤压滞后分析。第二个研究领域是关于吸附和解吸的动力学。PI在这里的目标是使用模拟动态摄取实验来研究迟滞区域状态的稳定性。PI使用这种方法来确定蒙特卡罗模拟中遇到的滞回回路的重要性，并研究孔隙阻塞在滞回中的作用。提出的工作涉及粗粒度晶格模型的动态模拟以及在汞孔隙度测量中的应用。PI还计划在纳米技术应用的背景下，将这些技术扩展到受限几何的润湿动力学研究。更广泛的影响：这项研究虽然是基础性的，但与应用密切相关，特别是在多孔材料表征方面。传统上，工程师和其他使用多孔材料的人不得不使用相当不精确的数量来观察多孔材料的微观结构，如孔隙体积、表面积和孔径分布。预计该项目可以为多孔材料表征的新方法提供基础。从催化和分离等传统领域到纳米技术等新兴领域，多孔材料的应用具有巨大的潜在影响。该研究项目通过研究生、博士后学者和本科生的参与，具有很强的教育成分。学生们定期参加并在重要会议上展示他们的作品。研究小组会议的部分目的是培养学生交流他们的研究成果的能力，我们的研究生参加本科课程的教学，作为他们学位课程的教育要求。该项目包括与工业界（Quantachrome Corporation）的合作，以及与德国柏林工业大学的研究人员的国际合作。

Peter A. Monson, University of Massachusetts - Amherst"Modeling Adsorption in Complex Porous Structures: Equilibrium, Hysteresis and Dynamics"This research will use molecular modeling to understand the behavior of fluids confined in porous materials with complex pore structures. The primary goal is to develop a more refined understanding of how the combined effects of molecular interactions and the structure of the porous material over several length scales yield particular kinds of adsorption behavior. This understanding is central to important applications such as separations and catalysis, as well as in porous materials characterization. A combination of dynamical as well as equilibrium modeling techniques is a central feature of this project. Two complementary areas of research are planned.In the first area the PI is concerned with coarse-grained lattice models of adsorption/desorption in complex pore structures. The goal of this work is to develop a framework for understanding the relationship between adsorption measurements and the porous material microstructure - particularly for states in the capillary condensation and hysteresis regime. The recent work has shown that coarse-grained lattice models provide important insights into hysteresis and the PI seeks to build on this in several ways. In the proposed work the PI will extend the range of materials that can be treated by this approach, including applications to a variety of mesoporous silica materials, and apply the approach to analysis of intrusion/extrusion hysteresis in mercury porosimetry.The second research area is concerned with the dynamics of adsorption and desorption. The PI's goal here is to use simulations that mimic dynamic uptake experiments to investigate the stability of states in the hysteresis region. The PI has used this approach to establish the significance of the hysteresis loops encountered in Monte Carlo simulations and to investigate the role of pore blocking in hysteresis. The proposed work deals with dynamical simulations of coarse-grained lattice models as well as application to mercury porosimetry. The PI also plans to extend these techniques to the study of wetting dynamics in confined geometries in the context of nanotechnology applications.Broader Impact: The research while fundamental is closely linked with application, especially in the context of porous materials characterization. Traditionally engineers and others using porous materials have had to view the porous material microstructure using rather imprecise quantities like the pore volume, surface area and pore size distribution. It is anticipated that the project could provide a foundation for a new approaches to the characterization of porous materials. There is substantial potential impact in applications of porous materials ranging from traditional areas such as catalysis and separations to emerging areas in nanotechnology.The research program has a strong educational component through the involvement of graduate students, postdoctoral scholars and undergraduates. The students regularly attend and present their work at major conferences. Research group meetings are designed in part to develop the ability of students to communicate their research achievements, and our graduate students participate in teaching undergraduate courses as an educational requirement of their degree program. The project features collaboration with industry (Quantachrome Corporation) as well as an international collaboration with researchers at the Technical University of Berlin, Germany.