Ruthenium dioxide has attracted considerable interest as a possible substitute for platinum-based industrial catalysts for ammonia oxidation ever since Wang et al [1] showed RuO2(110) to exhibit NO selectivity around 530 K, under UHV conditions. Related density functional theory (DFT) based kinetic Monte Carlo (KMC) simulations [2] provided further support for this selectivity.  Perez et al [3], however, find N2 to be the dominant product in experiments at ambient pressure on polycrystalline RuO2 samples. To address possible pressure and/or material gap in the products, we have extended our DFT-based KMC calculations to include reactions rates for a large set of reaction intermediates that may be found under ambient conditions.  We have also carried out simulations using data-bases proposed by Perez et al [3] and others. Interestingly, all databases show NO to be the dominant species under UHV conditions at or above the peak NO desorption temperature. On the other hand, we find that N2 is the dominant product under ambient conditions. The rationale for the pressure gap is the activation of secondary reaction of NO i.e. active formation and decomposition of N2O to N2, owing to sufficient supply of N species, which is a result of active NHx decomposition by plentiful O species on RuO2(110). Furthermore, we show that reliable prediction of selectivity requires consideration of competing reaction processes as made feasible in  kinetic simulations such as KMC.[1] Y. Wang, K. Jacobi, W. -D Schone, G. Ertl, J. Phys. Chem.B 109, 7883 (2005)[2] S. Hong, A. Karim, T.S. Rahman, K. Jacobi, and G. Ertl, J. Catal., 276, 371 (2010).[3] J. Perez-Ramirez, N. Lopez, and E. V. Kondratenko, J. Phys. Chem. C.114, 16660 (2010).* Work supported in part by DOE

Combined DFT+KMC study of selective oxidation of NH<sub>3</sub> on rutile RuO<sub>2</sub> (110) at ambient pressures

246th National Meeting (2013)

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Combined DFT+KMC study of selective oxidation of NH3 on rutile RuO2 (110) at ambient pressures

Combined DFT+KMC study of selective oxidation of NH₃ on rutile RuO₂ (110) at ambient pressures