Structure Selectivity of Supported Pd nanoparticles for Catalytic NH3 Oxidation resolved using combined Operando Spectroscopy

Ellie Dann, Emma Gibson, Rachel Blackmore, Richard Catlow, Paul Collier, Arunabhiram Chutia, Tugce Eralp Erden, Christopher Hardacre, Anna Kroner, Maarten Nachtegaal, Agnes Raj, Scott Rogers, Rebecca Taylor, Paul Thompson, George Tierney, Constantinos Zeinalipour-Yazdi, Alexandre Goguet, Peter Wells

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Abstract

The selective catalytic oxidation of NH3 to N2 presents a promising solution for the abatement of unused NH3-based reductants from diesel exhaust after treatment. Supported Pd nanoparticle catalysts show selectivity to N2 rather than NOx, which is investigated in this work. The link between Pd nanoparticle structure and surface reactivity was found using operando X-ray absorption fine structure spectroscopy, diffuse reflectance infrared Fourier-transformed spectroscopy and on-line mass spectrometry. Nitrogen insertion into the metallic Pd nanoparticle structure at low temperatures (<200 °C) was found to be responsible for high N2 selectivity, whereas the unfavourable formation of NO is linked to adsorbed nitrates, which form at the surface of bulk PdO nanoparticles at high temperatures (>280 °C). Our work demonstrates the ability of combined operando spectroscopy and density functional theory calculations to characterize a previously unidentified PdNxspecies, and clarify the selectivity-directing structure of supported Pd catalysts for the selective catalytic oxidation of NH3 to N2.
Original languageEnglish
Pages (from-to)157–163
JournalNature Catalysis
Volume2
Early online date28 Jan 2019
DOIs
Publication statusPublished - 01 Feb 2019

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