Gold in Three-way Catalysis

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In the first stage of the present project on Au-containing three-way catalysts, a drastic dependence of the catalytic behavior of bimetallic Pd-Au systems on the nature of the support was found. When supported on La-doped alumina, gold acts as a poison with respect to the Pd component and even enhances the adverse property of Pd to release nitrous oxide at elevated temperatures. When supported on CeZrO2, properties of Pd and Au combine favorably, so that Au-containing three-way catalysts may become a reality provided that thermal stability requirements can be fulfilled. The project aims at elucidating the origin of these differences by structural characterization of relevant materials (e.g. by XPS, XAFS, LEIS, HAADF-STEM), but also by operando XAFS studies in model exhausts of different composition, at investigating the catalytic behavior of the bimetallic catalysts after thermal stress and its structural reasons, and if necessary at identifying strategies for stabilization of the catalysts under high temperatures.