CAREER: Fundamentals of the Relationship between Pore Structure and Transport of Light Gases in Materials with a Hierarchy of Pore Sizes

职业：具有孔径等级的材料中孔结构与轻气体传输之间关系的基础

• 批准号: 0951812
• 负责人: Sergey Vasenkov
• 金额: $ 40万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-15 至 2016-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0951812&HistoricalAwards=false
• 关键词: CAREER; Fundamentals; Relationship; between; Pore

This NSF award by the Chemical and Biological Separations program supports work by Professor Sergey Vasenkov at University of Florida to obtain fundamental knowledge of the relationship between structural properties of materials with a hierarchy of pore sizes and transport properties of gases in these materials on different length scales of molecular displacements. Porous membranes fabricated for separations of gas mixtures are usually structurally heterogeneous. In particular, mixed matrix membranes contain interconnected networks of pores of different sizes, i.e. networks of micropores with pore sizes approaching the sizes of gas molecules and networks of much larger mesopores. Such membranes have great potential for effective separations of small gas molecules such as CO2, CH4, and N2. Over the last decade significant progress has been made in understanding gas transport in pore networks with uniform or similar pore sizes. At the same time, diffusion in materials containing a hierarchy of pore networks with very different pore sizes is still poorly understood. The research goal of the project is to quantify different types of gas transport on small (i.e. micrometer and submicrometer) length scales in materials with a hierarchy of pore networks and to find a relationship between such transport and macroscopic long range diffusion. The proposed studies focus on measurements of sorbate diffusion along and through the interfaces between microporous particles and their surroundings. In addition, the effect of correlated motions of sorbate molecules on small length scales on the long range diffusion will be investigated. The hypothesis is that these types of transport can make a significant and quantifiable contribution to long range diffusion of gases in hierarchical porous materials. Measurements of gas transport will be carried out using a unique experimental approach: pulsed field gradient (PFG) NMR at high field (17.6 T) and high gradients (up to 36 T/m). Experimental studies will be complemented by dynamic Monte Carlo simulations.In the framework of the education plan of the project a new departmental program for minority undergraduate students will be introduced. The program includes organizing mentoring seminars, providing research experiences, and pairing freshmen minority students with the students who obtained research experience in the groups of the PI and other faculty members of the department. High field and high gradient PFG NMR hardware and measurement methodology will be developed as a new multi-user resource at the National Magnet Lab. The PI's plans to reach this goal include: (i) training his students to advise other users on the procedures of PFG NMR measurements, and (ii) development of a manual for such measurements. The outreach activities include expansion of the local symposium (JSEHS) for high school teachers and students and hosting 10th and 11th grade students at the PI?s group during summer months.The proposed research will quantify different types of gas transport on small length scales and establish a quantitative relationship between these types of transport and macroscopic long range diffusion in porous membranes and related materials. Molecular fluxes through macroscopic porous systems are determined by long-range diffusivities. Hence, new knowledge generated in the proposed research will enable designing concrete strategies for optimizing gas fluxes in porous membranes while preserving separation selectivities.

化学和生物学分离计划的NSF奖支持佛罗里达大学Sergey Vasenkov教授的工作，以获得有关材料的结构特性与孔径层次的结构特性之间的基本知识，这些材料的层次结构和这些材料中气体的运输特性在不同长度的分子位移。用于分离气体混合物的多孔膜通常在结构上是异质的。特别是，混合基质膜包含不同尺寸的孔的互连网络，即孔尺寸的微孔网络接近气体分子的大小和更大中孔的网络。这种膜具有有效分离小气体分子（例如CO2，CH4和N2）的巨大潜力。在过去的十年中，在了解孔隙均匀或类似孔径的孔网络中的气体传输方面取得了重大进展。同时，在包含孔网络层次层次结构的材料中的扩散仍然鲜为人知。该项目的研究目标是在具有孔网络层次的材料中量化不同类型的气体传输（即微米和亚微米）的长度尺度，并找到这种传输与宏观远距离扩散之间的关系。拟议的研究集中于沿着微孔颗粒及其周围环境之间的界面进行刺刺扩散的测量。另外，将研究马山分子分子对远程扩散的相关运动对远程扩散的影响。假设是，这些类型的运输可以为分层多孔材料中气体的远距离扩散做出显着且可量化的贡献。气体传输的测量将使用独特的实验方法进行：高场（17.6 T）和高梯度（最高36 t/m）的脉冲场梯度（PFG）NMR。实验研究将由动态的蒙特卡洛模拟进行补充。该计划包括组织指导研讨会，提供研究经验，并将新生少数民族学生与在PI组和其他教职员工的研究经验的学生配对。高场和高梯度PFG NMR硬件和测量方法将在国家磁铁实验室中作为新的多用户资源开发。 PI实现此目标的计划包括：（i）培训他的学生就PFG NMR测量程序的过程建议其他用户，以及（ii）开发用于此类测量的手册。宣传活动包括在夏季，在PI的小组中扩展当地的研讨会（JSEHS），并在PI的小组中托管10年级和11年级的学生。拟议的研究将以较小的长度尺度上量化不同类型的气体运输，并在这些类型的运输和宏观范围之间建立定量的关系，并在孔中有毛孔的相关材料和相关材料之间进行量化。通过宏观多孔系统的分子通量由远程扩散率确定。因此，拟议的研究中产生的新知识将使设计具体策略，以优化多孔膜中的气体通量，同时保持分离选择性。