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Synergism between palladium and nickel on Pd-Ni/TiO2 for H2-SCR: A transient DRIFTS study

[Display omitted] •Synergism between Pd and Ni on Pd-Ni/TiO2 catalyst was observed for H2-SCR.•The addition of Ni to Pd/TiO2 enhanced the rate and distance of hydrogen spillover.•Ni additive enhanced the activities of bidentate and monodentate nitrates.•The monodentate nitrates reacted with spiltove...

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Bibliographic Details
Published in:Journal of catalysis 2020-01, Vol.381, p.204-214
Main Authors: Hu, Zhun, Yong, Xiang, Li, Dan, Yang, Ralph T.
Format: Article
Language:English
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Summary:[Display omitted] •Synergism between Pd and Ni on Pd-Ni/TiO2 catalyst was observed for H2-SCR.•The addition of Ni to Pd/TiO2 enhanced the rate and distance of hydrogen spillover.•Ni additive enhanced the activities of bidentate and monodentate nitrates.•The monodentate nitrates reacted with spiltover hydrogen to form active NHx species.•In situ NHx species are key intermediates for the enhancement of H2-SCR activities. The effect of nickel additive on Pd/TiO2 catalyst for selective catalytic reduction of NO with H2 in presence of O2 was investigated. Synergistic effects between palladium and nickel were found on the catalytic activity and N2 selectivity for the H2-SCR reaction. Hydrogen adsorption isotherm and transient reaction experiment results showed that the nickel additive enhanced the distance and rate of hydrogen spillover. Operando diffuse reflectance infrared spectroscopy (DRIFTS) with transient experiments indicated that addition of nickel to Pd/TiO2 led to the formation of extra active monodentate nitrates, and enhanced the activities of the bidentate nitrates. These positive effects on the formation of spiltover hydrogen and active adsorbed NOx species led to the promotional effect on the extra reaction intermediate NHx species, which was crucial for the enhancement of H2-SCR activity. All these results, from a view of reaction mechanism, provided a promising way for rational preparation of high-performance H2-SCR catalysts.
ISSN:0021-9517
1090-2694
DOI:10.1016/j.jcat.2019.11.006