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Investigation of Surface Structures on Supported Vanadium Oxide Model Catalysts


EMSL Project ID
34713

Abstract

Vanadium oxo clusters supported on a high surface area support constitute an active, selective catalyst for several important reactions, including oxidation of alcohols to aldehydes and oxidative dehydrogenation of alkanes to alkenes. However, the techniques conventionally used to study such clusters on high surface area powders are limited in their ability to provide detailed information about the chemical structures of the active species in these catalysts. To overcome these limitations, we are developing a two-dimensional model catalyst system in which a silicon wafer serves as the substrate for the metal oxo clusters. In this Science Theme proposal, we propose to use RBS and XPS to determine the surface composition and oxidation state of vanadium oxo clusters grafted onto thin metal oxide supports built on a silicon wafer substrate. We also propose to use ToF-SIMS to explore the connectivity and degree of oligomerization of vanadium oxo units, and AFM to study the spatial distribution of active sites according to their degree of oligomerization. From these experiments, we will gain information about connectivity, dispersion, and support effects that has proven difficult to extract from conventional analysis of powdered samples. Altogether, the work here will help us to better understand structure-activity relationships in this important catalyst system, and thereby work toward the goal of rationally designing more selective, more active catalysts.

Project Details

Project type
Large-Scale EMSL Research
Start Date
2009-10-05
End Date
2011-09-30
Status
Closed

Team

Principal Investigator

Alexis Bell
Institution
University of California, Berkeley

Team Members

Andrew Getsoian
Institution
University of California, Berkeley