Invited Paper SS-TuM1
Preparation, Characterization and Catalytic Activity of Model WO3 Catalysts
Tuesday, October 30, 2012, 8:00 am, Room 21
Supported early transition metal oxides have important applications in numerous catalytic reactions. In our studies, conversion of small aliphatic alcohols to alkenes, aldehydes/ketons, and ethers is employed to probe the structure-activity relationships on model WO3 catalysts. To understand how the structure and binding of WO3 species affect catalytic properties we prepared a number of well-characterized systems. Direct sublimation of WO3 solid was used to generate cyclic gas-phase ( WO3)3 clusters. As shown in our matrix isolation experiments, sublimation leads to pure (WO3)3 clusters. The ( WO3)3 clusters were embedded in alcohol matrices and their support-free chemistry was explored in subsequent temperature programmed reaction experiments. Model supported catalysts were created by depositing (WO3)3 clusters on TiO2(110) and FeO(111) and subsequently characterized using scanning tunneling microscopy and surface sensitive spectroscopies. In other studies, epitaxial and nanoporous thin WO3 films were prepared on Pt(111). The catalytic chemistry of all the systems is compared and contrasted with that observed on unsupported (WO3)3 clusters. Calculations employing Density Functional Theory provide molecular-level mechanistic insight into the role structure and binding of (WO3)3 clusters to the support plays in determining their catalytic properties.
This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences and performed in Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is a multiprogram national laboratory operated for DOE by Battelle.