Gas phase catalytic application of nanoporous gold

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The aim of subproject 1 (in collaboration with SP2) of the research unit FOR 2213 is a thorough clarification of how different options to prepare npAu catalysts influence the structure and composition and in turn the catalytic properties for different areas of application (total oxidation, partial oxidation). In addition to npAu made from AuAg (focused upon in the first period) also npAu made from AuCu will be included in the studies, as residual Cu and Ag can be involved in different mechanisms to activate molecular oxygen. In addition to monolithic samples where mass transport limitations are particularly prominent (due to the macroscopic extension of the samples) routes to powder samples will be sought. These catalysts will be compared to catalysts prepared in SP9 (supported nanoparticles) aiming at an understanding of the advantages or disadvantages in terms of a controlled preparation and thus a controlled tuning of catalytic properties (including mass transport limitation). In collaboration with S. Vasenkov at the University of Florida at Gainesville measurements with respect to the mass transport, i.e., diffusion of reactant molecules in different npAu samples will be conducted. The resulting diffusivities or tortuosities can be used to disentangle the macro kinetics into the micro kinetics (surface reaction) and mass transport. In this way a full understanding of the overall performance of the npAu catalysts is feasible. The range of reactions studied will range from CO oxidation (total oxidation), methanol and ethanol oxidation (partial oxidation, continuation of the studies in period 1) and propene oxidation (oxidation to epoxides). The aim is a detailed understanding of structural and compositional preconditions for different (proto)types of oxidation reactions in collaboration with model experiments (SP5), theory (SP7 and SP8) and liquid phase catalysis (SP2).