Kinetic Synergy between Supported Ir Single Atoms and Nanoparticles during CO Oxidation Light-Off
2021
Thompson, Coogan B. | Lu, Yubing | Karim, Ayman M.
Supported metal single-atom catalysts often exhibit different reactivities than their nanoparticle analogues. Such differences provide unique opportunities in terms of their practical applications. However, single atoms and nanoparticles often coexist under reaction conditions. In this work, we modeled the CO oxidation on a MgAl₂O₄ supported Ir with different mixtures of single atoms and nanoparticles. We demonstrate the pitfalls in determining reaction parameters for isolated systems if a minority species is present. More importantly, we show a kinetic synergy between single atoms and nanoparticles for CO oxidation light-off and we present optimization strategies to increase the catalyst activity. Specifically, we optimize the ratio of the single atoms and nanoparticles and mass of catalyst to increase activity for established reaction conditions. The optimization results show that the temperature required for 99% conversion can be decreased or a lower metal weight can be used to achieve the same conversion. The results highlight how the different mechanisms and kinetics on single atoms and nanoparticles can be advantageous to optimize the catalyst performance for practical applications, such as their use in catalytic converters.
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