Oberflächendynamik von inverser Ni- und Cu- Katalysatoren: Neue Konzepte für die CO2-Hydrierung durch Promotierung mit reduzierbaren Oxiden

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The promotion of metallic hydrogenation catalysts by oxides plays a major role in the activation and conversion of CO2. Starting from the industrially applied Cu/ZnO catalyst, this approach will be conceptually extended in this project to fundamentally better understand it and to fully exploit its potential. Here, the focus is on the surface dynamics of "inverse" metal oxide/transition metal catalysts under CO2 hydrogenation conditions. The inverse character of the catalysts studied provides new insights into the dynamic interplay between reducible metal oxides and the surface of transition metals. This is achieved by using a redox-inert support to stabilize the transition metal particles and depositing the metal oxide component on their surface. This approach has already been successfully tested in the first funding period of SPP2080 using MgO-supported ZnOx/Cu catalysts. The aim of this project is to deepen this knowledge and to transfer it to Ni as a new transition metal and Ga2O3 as a new reducible oxide. This will result in the combinations of the four metal oxide/transition metal (MO/TM) catalysts ZnOx/Cu, GaOx/Cu, ZnOx/Ni and GaOx/Ni. Importantly, all four systems can form alloys or intermetallic compounds under reducing conditions, but differ in the heat of formation of the alloy/intermetallic compound and the reducibility of the metal oxide, thus providing a suitable material base to systematically investigate and generalize our findings on the ZnOx/Cu system obtained in the first funding period. In the first funding period of SPP2080, the ZnOx/Cu system was investigated in detail to what extent surface alloys are formed. The associated dynamics were elucidated by targeted synthesis of ZnOx/Cu catalysts on MgO supports, operando X-ray spectroscopy, and theoretical modeling. The transfer to new materials now enables the vision of developing a deep and comprehensive understanding of the dynamics and associated catalytic behavior of these inverse metal oxide/transition metal catalysts in order to specifically exploit these interfacial phenomena to improve activity and selectivity in the hydrogenation of CO2. This will contribute to the general understanding of the dynamics of such MO/TM catalysts and control their surface structure by reaction conditions. These findings will be applied to the industrially important methanol synthesis as well as to CO2 hydrogenation reactions in general under dynamic conditions.