For high temperature chemical reactions in solid oxide fuel cells and methane steam reformers, catalyst stability is an important issue. In many cases, metal nanocatalysts are supported by thermally stable oxide supports. This talk focuses on metal nanoparticles formed by partial decomposition of oxide and their exceptional robustness. This phenomenon, metal exsolution, has been known for some time and is used in formulations of automotive emission control catalysts. The ability to re-dissolve and exsolve the metal via redox cycling has a merit of nanoparticle regeneration. However, the mechanism by which the transition metal is exsolved from the oxide host is still poorly understood. My recent contribution looks into the mechanism for the evolution of the unique metal-oxide dual phase structure. I have used well-defined model systems and detailed structural analysis to characterize the nucleation and exsolution of Ni particles. I will show how interesting properties of resistance against coarsening and carbon fiber formation are linked to the particle-in-a-pit morphology. Another application area of this catalyst system is membrane reactors. Syngas production via methane steam reforming is an important industrial process by which hydrogen is produced in mass scale. However, it requires high energy input due to endothermic nature of the reaction. Using oxygen transport membrane, one can combine air separation and methane partial oxidation to reduce energy cost. I will show how exsolution catalyst can increase the oxygen flux by reducing the surface reaction resistance.

<i>In-situ</i> grown metal nanocatalysts from oxide support

254th National Meeting (2017)

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In-situ grown metal nanocatalysts from oxide support