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

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.