Nucleation and growth studies of nanoporous materials using synchrotron and neutron radiation techniques

纳米多孔铝硅酸盐和铝磷酸盐是当代材料和催化化学中的关键体系，近几十年来记录了大量合成微孔框架材料。这些体系通常含有AlO4和SiO4或AlO4和PO4角共享四面体，形成整个组装体，导致具有一定范围的孔尺寸的一维链、二维层状或三维开放骨架结构。具有不同孔或笼尺寸和各种化学组成的新微孔材料的合成背后的主要推力是设计引入特定形状选择性和区域选择性性质的新型催化体系。这些无机非均相催化剂易于处理，可以再循环，并且在许多情况下可以调节以产生最少量的副产物，并且具有用于化学品的大规模生产的潜力。在这个项目中，我们建议进行详细的研究，以了解这些纳米多孔系统的形成。我们要解决的关键问题是（1）什么是成核物质，（2）成核物质的结构是什么，它与最终结晶产物是否有任何相似之处，以及（3）在给定条件下形成特定结晶产物的机制是什么。为了回答这些问题，有必要在操作（热液）条件下进行调查，并确定快速生长的结构，有必要使用时间分辨的先进表征技术。我们建议使用的技术是小角X射线散射法，以确定在成核过程的初始阶段形成的颗粒的大小和形状。同时，我们将使用广角X射线散射监测结晶产物。为了确定在初始阶段形成的非晶颗粒的结构，我们将使用适用于非晶固体的总散射方法，特别是X射线和中子衍射方法。从这些研究中获得的信息将提供有关结晶前网络形成机制的新信息，这是生产最终结晶产品的原因。我们将使用先进的同步辐射和中子辐射光源进行原位实验。通过理解这一过程，我们将能够开发策略来设计合成条件，以产生新的和新颖的纳米多孔结构。

Nanoporous aluminosilicate and aluminophosphates are key systems in contemporary materials and catalytic chemistry, with a large number of synthetic microporous framework materials being documented over recent decades. These systems contain, in general, AlO4 and SiO4 or AlO4 and PO4 corner sharing-tetrahedra forming the entire assembly resulting in either one-dimensional chain, two-dimensional layered or three-dimensional open-framework structures with a range of pore dimensions. The main thrust behind the synthesis of new microporous materials, with different pore or cage dimensions and various chemical compositions, is to design novel catalytic systems that introduce specific shape selective and regio-selective properties. These inorganic heterogeneous catalysts are easy to handle, can be recycled and in many instances can be tuned to produce a minimum amount of side-products, and have the potential for use in the large-scale production of chemicals. In this project we propose to carry out a detailed study to understand the formation of these nanoporous systems. The key questions we will address are (1) what are the nucleating species, (2) what is the structure of the nucleating species and does it have any resemblance to the final crystalline product and (3) what is the mechanism involved in the formation of a specific crystalline product under a given conditions. To answer these questions it is necessary to carry out investigations under operating (hydrothermal) conditions and to determine structures that grows rapidly, it is necessary to use time-resolved advanced characterisation techniques. The techniques we propose to use are small-angle X-ray scattering method to determine the size and shape of the particles that are formed during the initial stages of the nucleation processes. Simultaneously we will monitor the crystallising product using wide-angle X-ray scattering. To determine the structure of the non-crystalline particles formed at the initial stages, we will use total scattering methods, in particular X-ray and neutron diffraction methods, applicable to amorphous solids. The information obtained from these studies will provide new information on the mechanism of the network formation prior to crystallisation, which are responsible for the production final crystalline product. We will use the advanced Synchrotron Radiation and Neutron Radiation sources to perform the in situ experiments. By understanding this process we will be able to develop strategy to design synthesis conditions to produce new and novel nanoporous structures.