Study Of Nano-catalysts Composed Of Vanadium

The explosive growth of nanoscience, increasing demand for energy and more stringent environmental regulation have provided both opportunities and challenges for the development of heterogeneous catalysis. Designing of new green catalytic processes and improving raw materials and energy utilization efficiency of existed processes require fundamental knowledge on reaction mechanism and on chemistry in catalyst preparation method. This thesis focused on the application of novel nanostructured materials on challenging reactions, such as selective oxidation. The mam contents are:1. Study on gold-ceria catalytic system was reviewed. Controversies on gold oxidation state and active sites were described. Synthesis of CeVO4nanocrystals by hydrothermal treatment and preparation of Au/CeV04catalyst using deposition-precipitation method. The properties of the samples in CO oxidation reaction are tested. It was found that changes in support lattice distance can tune catalytic performance of Au nanoparticles. It was also found that vanadium had a poisoning effect on ceria based gold catalyst for CO oxidation.2. A simple sonochemical-hydrothermal method was proposed to synthesize vanadium oxide nanobelts. Hexadecylphosphonic acid was introduced onto the surface of vanadium oxide nanobelts and bulk vanadium oxide to tune their catalytic property. These materials were used as catalysts for gas-phase toluene oxidation. Enhanced catalytic activity was obtained for vanadium oxide nanobelts in comparison with the bulk oxide. When doped by hexadecylphosphonic acid, tuning lattice oxygen activity led to higher selectivity to benzaldehyde and benzoic acid on both bulk and nanobelt-like vanadium oxides.3. Investigation of morphology effect of supports on oxidative dehydrogenation of propane reaction. At low surface vanadium density, magnesium oxide nanotube supported vanadium catalyst had higher selectivity toward propylene than conventional magnesium oxide. The catalytic activity had a highest point as the increasing surface vanadium density, while selectivity to propylene is monotonically increasing.4. Designing a new strategy for assemblying metal nanoparticles into a solid matrix. Generally, colloidal metal nanoparticles should be immobilized on solid support in order to improve its seperation and recyclability. In this thesis, Ni nanoparticles were modified with vinyl phosphonic acid and then co-polymerizes with styrene and divinylbenzene using suspension polymerization method. The Ni NPs were imbedded into Polystyrene matrix. This procedure has the advantage of being able to use different acid groups in order to tune catalytic performance.