(573f) Exploring Ruthenium Metal-Support Interactions for the Low-Temperature Partial Oxidation of Methane

Emmett D. Goodman, Liheng Wu, Matteo Cargnello

Department of Chemical Engineering and SUNCAT Center for Interface Science and Catalysis, Stanford University, Stanford, CA 94305, USA

Industrially, the transformation of methane to syngas stands as an invaluable reaction, the latter products being converted downstream into valuable bulk chemicals such as methanol, ammonia, and synthetic fuels. The effective processing of methane will also limit the detrimental environmental impact of methane via industrial flaring. Steam or bireforming are common routes for methane conversion to syngas, but work at high temperatures because of their endothermic nature. Methane partial oxidation (CH₄ + ½ O₂ = CO + 2 H₂) is exothermic and benefits from more favorable thermodynamics. Thus, there are significant incentives to explore catalysts that can partially oxidize the pollutant methane, with high selectivity and yield, into an industrially relevant feedstock.

In order to rationally design such a catalyst, it is important to understand the underlying effect of the catalyst support. The catalyst support determines the spatial distribution, and often significantly alters the electronics of, supported nanoparticles. It therefore plays a large role in governing the overall system activity. However, in systems with differing support surface areas and nanoparticle coverages and size distributions, it is often difficult to discern the exact interaction between the nanoparticle and the support. Using monodisperse preformed Ru nanoparticles, and a system of supports with similar surface areas, here we show how to bypass such limitations and deconvolute these effects. With these methods we can back out important structure-property relations. We therefore find that selectivity and yield are strongly dependent on the support type, and mildly on Ru particle size. Using this information, we can gain fundamental mechanistic insight regarding methane partial oxidation on supported ruthenium systems, and work to design more effective catalysts.