Graduate Thesis Or Dissertation
 

Oxygenate Reactions over PdCu and PdAg Catalysts: Influence of Electronic and Geometric Effects

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/cj82kf24s

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  • Bimetallic catalysis is a promising way to tune the catalytic properties of heterogeneous catalysts. In particular, bimetallic catalysts are extensively used to enhance the selectivity of monometallic catalysts in a variety of contexts, from oxidation catalysis to oxygenate coupling. In this work, we investigate PdxCuy/SiO2 and PdxAgy/SiO2 catalysts in the context of oxygenate upgrading for biofuels. We measure the rates of decarbonylation and hydrogenation of butyraldehyde, the reactive intermediate for Guerbet condensation and correlate them with the properties of the catalysts via a range of characterization efforts. Temperature-programmed reduction and chemisorption experiments are conducted to study the preparation temperature-induced reactivity and dispersion trends of the catalysts respectively. Most importantly, data obtained from operando EXAFS and XANES evinced variations in the surface composition of the catalysts. The data for PdxCuy/SiO2 show clear dominance of geometric (ensemble) effects over the improved selectivity in the kinetics. More significantly, the electronic effects of alloying are observed to modify the chemical reactivity of metallic surfaces. However, the PdxAgy/SiO2 catalysts did not follow the same trend. We attribute this to the lack of electron exchange is observed between Pd and Ag. We use the implications of these findings to provide valuable design principles for oxygenate catalysis.
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  • Ongoing Research
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  • 2020-03-21 to 2021-04-21

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