Microimaging of diffusion and reaction of guest molecules in MFI-type zeolite crystals

MFI型沸石晶体中客体分子扩散和反应的显微成像

• 批准号: 437340252
• 负责人: Professor Dr. Roger Gläser
• 金额: --
• 依托单位: Institut für Technische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/437340252?language=en
• 关键词: Microimaging; diffusion; reaction; guest; molecules

The gain in value-added products by the application of nanoporous materials for mass conversion and separation can never be faster than allowed by the transportation rate from the material interior to the surroundings. The rate of mass transfer within such materials is therefore, besides its relevance for fundamental research, among the key numbers deciding about their technological performance. Over decades, this type of information could only be deduced from “macroscopic” measurements, based on measurement of uptake and release rates with beds of crystals or pellets. Any message about the elementary processes of mass transfer had therefore to be based on model assumptions, which often were found to be wrong. Direct evidence about these inconsistencies was attained by advent of microscopic techniques of diffusion measurement, namely pulsed field gradient (PFG) NMR and microimaging by IR and interference microscopy, which often revealed discrepancies of orders of magnitude and did thus initiate a paradigm shift in our understanding of mass transfer in such materials. While microscopic diffusion techniques have so far been mainly applied to quite diverse nanoporous host-guest systems, selected with the main focus on demonstrating the potentials of these novel techniques quite in general, the present project aims on providing the proof of efficiency of these techniques by demonstrating the power of their evidence with a concerted application to MFI-type zeolite. It is a key material in zeolite catalysis and – given its highly complex pore structure – a challenging system for the in-depth study of mass transfer. The project will largely benefit from the complementarity of the two techniques. These are the options of NMR for revealing and analyzing reactants, intermediates and products during chemical reactions and for recording (via PFG NMR) the probability distribution of their displacement (including the short- and long-range diffusivities of all involved components) and the ability of microimaging to record transient concentration profiles which includes the measurement of intracrystalline fluxes. Though operating microscopically, with observing typically 1010 molecules both techniques provide data of high statistical relevance. The novel type of information aspired in the field of mass transfer includes the measurement of intracrystalline guest fluxes and the investigation of their mutual interference under multi-component adsorption, the in-depth study of transport enhancement by mesopores and the impact of transport resistances on the external surface as well as in composite materials (mixed matrix membranes). On considering conversion phenomena, guest-induced host variation (following indications of this phenomenon in first microimaging studies) just as host-induced guest variation shall be in the focus of our studies, in both cases in search for unprecedented information about the spatio-temporal variation over the individual MFI crystal.

通过在质量转换和分离中应用纳米多孔材料，增值产品的增值永远不会比从材料内部到周围环境的运输速度允许的速度更快。因此，此类材料中的传质速率除了与基础研究的相关性外，还决定其技术性能的关键数字。数十年来，这种信息只能根据“宏观”测量结果得出，这是基于用晶体或颗粒床的摄取和释放速率的测量来推论的。因此，关于传质基本过程的任何信息都必须基于模型假设，而模型假设通常被认为是错误的。有关这些不一致的直接证据是通过超显微镜技术的扩散测量技术，即脉冲场梯度（PFG）NMR以及通过IR和干扰显微镜微观成像来实现的，这通常揭示了我们对这种物质中大规模转移的理解的差异差异，因此确实启动了Paradigm的变化。迄今为止，显微镜扩散技术主要应用于相当多样化的纳米孔宿主 - 寄主系统，而主要重点是展示这些新技术的潜力，但总体而言，目前的项目旨在通过向MFi-i-fi-i-type zeepe zeepepe zeepepe zeepepe severy of Scoode of Scoods of Science提供这些技术的效率证明。催化和 - 鉴于其高度复杂的孔结构，是对传质的深入研究的挑战系统。该项目将在很大程度上受益于两种技术的互补性。这些是NMR在化学反应期间揭示和分析反应物，中间体和产品的选择，以及（通过PFG NMR）记录其位移的概率分布（包括所有相关组件的短和远距离扩散率）以及微成像的能力以及对瞬时浓度的透明浓度的能力，其中包括透明的透明液（包括内在氧化液）。尽管在显微镜下运行，但使用观察值1010分子两种技术都提供了高统计相关性的数据。在传质领域渴望的新型信息类型包括测量晶体内的客人通量以及对多组分添加吸收下的相互干扰的研究，中间膜对运输增强的深入研究以及在外部表面以及外部表面以及复合材料（混合矩阵MEMBRANES）对运输抵抗力的影响。在考虑转化现象时，宾客引起的宿主变化（以下是初次微成像研究中这种现象的迹象），就像宿主诱导的访客变异应成为我们的研究的重点，在这两种情况下，以寻找有关单个MFI晶体的空间变化的前所未有的信息。