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Multiscale studies of framework structure, composition and defect influences on small molecule behaviour in zeolites

沸石中骨架结构、组成和缺陷对小分子行为影响的多尺度研究

基本信息

批准号：
2282425
负责人：
金额：
--
依托单位：
University of Bath
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-2282425
关键词：
Multiscale studies framework structure composition

项目摘要

Zeolites are microporous silica-based solids with a highly modifiable structure. Their defining characteristic is that they contain pores of molecular dimensions. This feature has led to their widespread use in a range of applications such as catalysis (in the cracking and transformation of hydrocarbons in the fossil fuel industry), molecular sieving and water purification. They also have potential for further use in drug delivery systems and the agrochemical industry. All these processes require small molecules to enter the zeolite framework, diffuse through the pore system to an active site, where it can undergo a reaction, and to eventually diffuse out of the system. This means that the movement of molecules confined within the zeolite structure is of great interest as it can define their use. It can also guide which post-synthetic treatments may be applied to the zeolite to optimise its structure, and composition, and subsequent application. One of the most important factors affecting molecular behaviour within zeolites are the interactions with structural features and defects (such as cations, Bronsted acid sites, silanol nests and extra-framework aluminium). Currently, there is a significant research gap in gaining an accurate understanding of the effect of these features which will have high impact on the industrial applications of zeolites.Research question: This research aims to quantify and understand the effects of structural features on small molecule diffusion within zeolites on multiple scales - meaning that both experimental and theoretical techniques will be employed. A large combination of different structure types (i.e. variations in pore size and geometry), structural features (i.e. different counter ions, silanol nests, acid sites) and compositions (i.e. silicon to aluminium ratios) need to be investigated and in many different combinations to fully understand the effects of these variables and how they can interplay with each other.Objectives:Measure the effect structural features and defects on the diffusivity of small molecules (such as water, short chain hydrocarbons, ammonia). Initially, starting with water in zeolites containing Bronsted acid sites and silanol nest defects. Determine the effect of different cations (such as sodium, potassium, calcium) being incorporated in the zeolites.Investigate how framework topology, alongside other factors, can alter the molecular behaviour. Initially starting with industrially relevant structure types - such as ZSM-5 and FAU (Zeolite Y) - but with the potential to move further afield.Model these systems computationally via quantum mechanical calculations based on density functional theory alongside experimental techniques such as vibrational spectroscopy to investigate the molecular-scale behaviour. Investigate the nanoscale behaviour via simulation with classical molecular dynamics paired with quasielastic neutron scattering experiments. Together, the multiscale-multifaceted approach will allow the production of novel ideas and insights into how small molecules behave upon confinement within zeolites with varied compositions and defects present. There are multiple reasons why this research is appropriate for funding from the EPSRC. Firstly, the fundamental nature of the project, coming from a "bottom-up" approach keeps the UK globally competitive in research. On top of this, the nature of the study provides a long-term impact in terms of the understanding within zeolite science. And finally, it's impact on industry and therefore the economy due to the wide-ranging industrial applications - particularly catalysis - of these materials.Relevant EPSRC research areas:Computational and theoretical chemistryCatalysisFossil Fuel power generation

沸石是具有高度可改性结构的微孔二氧化硅基固体。它们的定义特征是它们含有分子尺寸的孔。这一特性使其广泛应用于催化（化石燃料工业中烃类的裂解和转化）、分子筛和水净化等领域。它们还具有进一步用于药物输送系统和农业化学工业的潜力。所有这些过程都需要小分子进入沸石骨架，通过孔系统扩散到活性位点，在那里它可以进行反应，并最终扩散出系统。这意味着限制在沸石结构内的分子的运动是非常感兴趣的，因为它可以定义它们的用途。它还可以指导哪些合成后处理可以应用于沸石，以优化其结构和组成以及随后的应用。影响沸石内分子行为的最重要因素之一是与结构特征和缺陷（如阳离子、布朗斯台德酸位点、硅烷醇巢和骨架外铝）的相互作用。目前，有一个显着的研究差距，在获得一个准确的理解这些功能的影响，这将有很大的影响沸石的工业应用。研究问题：这项研究的目的是量化和了解的影响沸石内的小分子扩散的结构特征在多个尺度上-这意味着实验和理论技术将被采用。不同结构类型的大型组合（即孔径和几何形状的变化）、结构特征（即不同的抗衡离子、硅烷醇巢、酸位点）和组合物（即硅铝比）需要进行调查，并在许多不同的组合，以充分了解这些变量的影响，以及它们如何相互作用。目标：测量结构特征和缺陷对小分子（如水、短链烃、氨）扩散率的影响。最初，从含有布朗斯台德酸位点和硅烷醇巢缺陷的沸石中的水开始。确定不同阳离子（如钠、钾、钙）被引入沸石的影响。研究骨架拓扑结构以及其他因素如何改变分子行为。最初从工业相关的结构类型（如ZSM-5和FAU（Y型沸石））开始，但有可能向更远的领域发展。通过基于密度泛函理论的量子力学计算以及振动光谱等实验技术对这些系统进行计算建模，以研究分子尺度的行为。通过经典分子动力学模拟与准弹性中子散射实验研究纳米级行为。总之，多尺度多方面的方法将允许产生新的想法和见解，以了解小分子如何在具有不同组成和缺陷的沸石内限制行为。这项研究适合EPSRC资助的原因有多种。首先，该项目的基本性质，来自“自下而上”的方法，使英国在研究方面具有全球竞争力。最重要的是，这项研究的性质对沸石科学的理解产生了长期影响。最后，由于这些材料广泛的工业应用（特别是催化），它对工业和经济产生了影响。EPSRC相关研究领域：计算和理论化学催化化石燃料发电