Studies on microporous materials

Microporous titanosilicates and vanadosilicates were synthesised characterized and photoreactivity studies were carried out. The titanosilicates synthesised were the titanosilicate pharmacosiderite and AM – 18 and the vanadosilicates were AM – 6, ETVS – 10, AM – 14 and VSH -13Na. A variety of different techniques were used in the characterisation studies including different X-Ray methods, vibrational spectroscopy, electron microscopy, and solid state NMR spectroscopy. The studies showed that the synthesised products were homogeneous and an insight into the structures of AM – 18 and AM – 14 was obtained. Raman spectroscopy was used to assess the levels of defects in large crystals of ETS – 10 and ETS – 4 by measuring the variation in the frequency of the Ti – O band and the width of this band. A similar study was done on large crystals of AM – 6. Raman spectroscopy showed that Ti – O stretching bands containing Ti(V) and Ti(IV) were present in AM – 18 structure. The frequency of the vanadyl bands in AM – 14 indicated that it could contain vanadyl chains. Photoreactivity studies using EPR spectroscopy, on the potassium titanosilicate pharmacosiderite showed an O- species, after UV irradiation in the presence of oxygen. When the partial pressure was reduced a superoxide and the anomalous ozonide species were observed. On changing the cation to a proton form, a superoxide anion radical was observed but no other oxygen radicals were observed. Attempted oxidation and reduction studies on VSH – 13Na were unsuccessful and HRTEM and nitrogen adsorption studies showed that the one-dimensional channels were blocked. Oxidation and reduction studies on AM – 14 indicated that the vanadium sites were easily accessible to gas phase.EThOS - Electronic Theses Online ServiceGBUnited Kingdo