Low Energy Electron Microscopy (LEEM) Studies of Nanoscale Resolved Reaction Kinetics on Catalytic Surfaces

Ian Harrison

Department of Chemistry, College of Arts & Sciences, UVa

Jack Hudson

Department of Chemical Engineering, School of Engineering & Applied Sciences, UVa

Low energy electron microscope (LEEM) is a surface science tool able to directly visualize and thereby understand some of the key nanoscale details of how transition metal surfaces turn over catalytic reactions, e.g., those of importance to the efficient production and use of sustainable energy fuels. Catalyst surface can be visualized at about 10 nm resolution with video rate imaging (up to 30 frames per second) at various temperatures (typically 300-1200 K). Currently, we are studying dissociative chemisorption of simple hydrocarbons on single crystal metal catalyst (platinum in this case) since it is often a rate limiting process in alkane reforming reactions. The role of the carbon (and graphite) adlayer formation and its dynamics during the dissociation and oxidation reactions is examined. The morphology of the surface under study can be controlled by argon ion sputtering at different temperatures. The gas is dosed through an effusive doser directed at the sample. It will later be replaced with a heated doser which will allow us to adjust gas temperature independently of the catalyst surface temperature.

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