Bridging The Materials Gap In Catalysis: Reactivity Studies Of Nanostructured Titania

ABSTRACT BRIDGING THE MATERIALS GAP IN CATALYSIS: REACTIVITY STUDIES OF NANOSTRUCTURED TITANIA David A. Bennett John M. Vohs Surface science studies of defect-free, single-crystal model catalysts have provided vital knowledge in the form of structure-activity relationships and elementary reaction mechanisms. However, there is some difficultly in extending this understanding to more complex systems, since these model catalysts typically lack the range of features that occur on the high surface area catalysts used in industry. This project seeks to bridge the gap between these two classes of materials by studying thin films of well-defined TiO2 nanocrystals with tunable size and morphology using traditional surface science techniques. This enables the controlled introduction of features lacking in single-crystal model catalysts, allowing for the formulation of more complex structure-activity relationships. The thermal- and photocatalytic reactions of methanol to produce methane, formaldehyde, dimethyl ether, and methyl formate on these TiO2 nanoparticles were investigated using temperature programmed desorption in ultra high vacuum. Results show clear effects of nanocrystal size and shape on the activity and selectivity of these reactions. This demonstrates the value of studying nanostructured metal-oxide catalysts to better understand the relationship between fundamental catalytic knowledge and the behavior of complex heterogeneous catalysts.