Synthesis and Catalytic Applications of Metal Oxide Based Materials in Particulate Form

Abstract

In this thesis, new sol-gel templating methods for the synthesis of titanium dioxide (TiO2) based catalysts in both bare and magnetic forms with or without gold nanoparticle decoration were developed, and their photocatalytic activity and plasmonic catalytic activity were investigated.In the first part of this thesis, monodisperse-porous bare titania microbeads were synthesized by new sol–gel templating method by using sodium sulfonate (-SO3Na) attached-polymethacrylate microbeads as template. Newly synthesized monodisperse-porous poly(3-chloro-2-hydroxypropyl methacrylate-co-ethylene dimethacrylate), poly(HPMA-Cl-co-EDMA) microbeads 5.4 µm in size were used as starting material for the preparation of -SO3Na attached-polymethacrylate template. The new sol-gel templating protocol was applied by treating -SO3Na attached-polymethacrylate microbeads with the titania precursor, titanium chloride (TiCl4) in an aqueous medium and washing subsequently with ammonia to obtain titania-polymer composite microbeads. The composite microbeads were calcined to have monodisperse-porous bare titania microbeads. The bare titania microbeads in the size range of 3.0-5.0 µm with crater-like or fine porous structures with the specific surface areas ranging between 50-91 m2 /g were obtained by changing the concentration and crosslinking density of -SO3Na attached-polymethacrylate template microbeads and the calcination temperature. The selection of a polymethacrylate template decomposed at lower temperatures with respect to poly(styrene-co-divinylbenzene), poly(S-co-DVB) templates, commonly used for synthesis of porous titania microbeads, allowed to perform the calcination of titania-polymer composite microbeads at lower temperatures. Hence, monodisperse-porous titania microbeads with higher specific surface area and a crystalline structure with higher percent of anatase phase could be obtained by performing calcination at lower temperatures.