UC Riverside

With growing interest in discovering novel catalytic materials, design choices such as synthesis methods, elemental compositions, and material structures must be understood to efficiently engineer catalysts. These choices must be made in respect to their planned process environment, such as whether the reaction is reductive or oxidative and how the material will be used. No one catalyst will be ideal for all conditions. For the sake of engineering then, materials must be tested not just at their ideal conditions, but also near their limits. In this dissertation, the focus is on understanding the behavior of select metal oxide catalysts under certain chemical environments.A brief study was done on the activity of gold-shelled iron nanoparticles synthesized by magnetron sputtering for the reduction of an environmental pollutant, 4-nitrophenol, using sodium borohydride. Constant UV-Vis monitoring was used to probe the kinetics of two sets of differently-sized, silica-embedded nanoparticles. A major focus was on engineering perovskite oxides for catalysis. Effort was made to study LaMnO3 and LaFeO3 modified by copper for the carbon monoxide oxidation reaction. This work described the increase in reactant conversion with increase dopant concentration and the consequence on thermal stability. Further work was done with LaMnO3 for the reverse water-gas shift reaction. The addition of copper was found to reduce the reduction temperature of the lattice yet had little effect on the composition of oxidation states for manganese. It was found in aging experiments that the copper dopant improved the reactivity of the catalysts at the cost of stability. Degradation was observed in the form of carbonate formation, which was not observed for the unmodified sample. Another focus was on the decomposition of a chemical warfare agent simulant, diisopropyl methylphosphonate (DIMP), on γ-Al2O3. The decomposition of DIMP on γ-Al2O3 was found to be dependent on prior exposure, which suggested in situ formation of active sites may be responsible for the composition of the gas products. Additionally, it was found that acetone and propene can originate from a byproduct reaction where isopropanol—a product from DIMP decomposition—reacts with γ-Al2O3 by either dehydrogenation or dehydration.