Aqeel, T.M.R.; (2008) Synthesis, characterisation, and sorption studies of porous inorganic materials. Doctoral thesis , University of London.

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Abstract

The aim of this project is to prepare various mesoporous hosts having hexagonal and cubic pore packing morphologies and improve their thermal, hydrolysis, and mechanical stabilities. Subsequently, we incorporate metal clusters and metal oxides into the pores to improve their sorption properties and to remove different types of sulphur compounds from organic liquids. Hydrolysis, thermal and hydrothermal tests are essential to determine the stability of mesoporous materials. Mesoporous silicates produced in this project, via standard methods of synthesis, failed the stability tests. However, by understanding and controlling individual preparation steps, in particular the ageing time, temperature, and reaction time allowed the production of relatively stable mesoporous materials. Moreover mesoporous materials prepared by various methods behave differently under given conditions. Monitoring the structural and morphological changes of these materials upon exposing them to different conditions it was possible to correlate their behaviour, in particular the structural stability, during doping of metal ions and oxides and sorption reactions. It was found that modified true liquid crystal templating (TLCT) and precipitating methods are more suitable than materials prepared by solvothermal techniques. We prepared micro clusters of zinc oxide, metallic gold, and silver into the pores (impregnation) of mesoporous silicate and aluminosilicate to improve the sorption ability of these hosts towards sulphur compounds. A modified method was developed by us to introduce gold and silver clusters into the mesoporous materials, which proved to be successful and more economical by decreasing the impregnation time from two weeks to only 30 minutes. This method involves two major steps 1) solvolysis of gold or silver precursors in alcohols, 2) heat treatments using reducing gas. This new method maintains the long-range order of the mesoporous structure as confirmed by the HRTEM and XRD. We were able to produce nano scale gold and silver clusters with an average size of ca 1 nm.

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