Smith, AJ; (2014) In-situ and ex-situ studies of heteroatom substituted nanoporous materials using advanced radiation techniques. Doctoral thesis , UCL (University College London).

Abstract

The work described in this thesis is concerned with the development of in-situ and ex-situ methods associated with synchrotron radiation techniques to understand the formation of nanoporous materials. The aim of this work is to expand knowledge of the mechanistic aspects of formation and growth of heteroatom substituted nanoporous systems to enable the development of new synthetic strategies for the production of specific nanoporous materials. in-situ small angle X-ray scattering was widely used for this purpose to study the formation of zeolite A and silicalite systems. New in-situ cells were developed to carry out the measurements. The results obtained clearly showed the growth depends on the ageing time of the precursor gel, constituents and temperature. More importantly a homogeneous nucleation and growth was observed for zeolite A and a more complex process was seen to take place for silicalite. Ti and Ge containing silicalite systems were studied in detail. X-ray absorption spectroscopic studies provided the clear evidence for Ge incorporation into the framework of silicalite, prior to the crystallisation. A new water soluble titanium precursor compound was developed to synthesise titanosilicate system containing ca 5 wt% titanium. XAS and IR were used for characterisation, and this material was also tested for the catalytic epoxidation of alkene. Finally, a novel method of preparing silicalite films/membranes and metal-substituted analogues was developed. Ti and Fe containing silicalite films were successfully prepared and characterised using a suite of X-ray techniques

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