Herauslösen von Metallnanoteilchen aus mesoporösen Perowskitoxiden
In heterogeneous catalysis, it is well-known that the surface area of the support and its interaction with the metal catalyst cover a pivotal role. Exsolution has been recently proposed as a novel synthesis strategy for supported metal nanoparticles catalysts, which are strongly anchored to the support and can be self-regenerated. Metal nanoparticles are here obtained via surface segregation of transition metal dopants from a perovskite oxide upon high-temperature oxygen release. So far, this approach has been applied to non-porous sintered structures. In the present proposal we aim to investigate the exsolution process of Fe, Co, Ni from mesoporous parental perovskite oxides of type La0.2Sr0.8Ti1 xMxO3 (LSTM, where M = Fe, Co, Ni and 0.05 ≤ x ≤ 0.2) in order to prepare advanced metal-supported catalysts. We intend to tune particle morphology by controlling the oxygen release not only through tuning process time, temperature, and gas atmosphere, but also varying a hitherto unexplored parameter as the nanoporosity of the matrix. Furthermore, we aim to investigate the metal-support interactions, as well as the mechanism of nanoparticle regeneration, so far known only for sintered exsolved systems. Precise and comprehensive assessment of the exsolved nanoparticle formation, stability against agglomeration, and regeneration will be studied for the first time using standard and anomalous small-angle X-ray scattering techniques, going beyond the limits of electron microscopy methods adopted so far. The catalytic properties of mesoporous exsolved materials with respect to the CO2 methanation reaction will be tested
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