Spectroscopic Evidences for the Size Dependent Generation of Pd Species Responsible for the Low Temperature CO Oxidation Activity on Pd-SBA-15 Nanocatalyst

[Display omitted] •Modified deposition precipitation (DP) method for synthesizing highly mono dispersed Pd nanoparticles of size 1-2 nm on SBA-15.•Onset of CO oxidation activity close to room temperature (50 deg C) for the reduced Pd-SBA-15 catalyst.•Evidences from ex-situ XPS and in-situ IR for eas...

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Veröffentlicht in:Applied catalysis. B, Environmental Environmental, 2020-09, Vol.272, p.118934, Article 118934
Hauptverfasser: Soni, Yogita, Pradhan, Sumanta, Bamnia, Mahesh K., Yadav, A.K., Jha, S.N., Bhattacharyya, D., Khan, Tuhin Suvra, Haider, M.A., Vinod, C.P.
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Sprache:eng
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Zusammenfassung:[Display omitted] •Modified deposition precipitation (DP) method for synthesizing highly mono dispersed Pd nanoparticles of size 1-2 nm on SBA-15.•Onset of CO oxidation activity close to room temperature (50 deg C) for the reduced Pd-SBA-15 catalyst.•Evidences from ex-situ XPS and in-situ IR for easily decomposable high valent PdO2 species being responsible for low temperature CO oxidation activity. A comprehensive size dependent CO oxidation activity has been demonstrated for Pd-SBA-15 catalysts with Pd NPs of varying sizes such as 1-2, 4-6 and 7-10 nm. Pd-SBA-15 catalyst with smallest sized NPs (Pd-S-N) has been synthesized by modified deposition precipitation method recently developed in our lab. Pd-S-N catalyst (reduced at 400 °C) demonstrated CO oxidation activity with lower light off temperature (50 °C), clearly one of the best reported for a Pd-silica system. A detailed XPS and in-situ DRIFTS analyses further supported by XAS and DFT calculations reveal the presence of easily decomposable highvalent Pd-oxide on co-ordinatively unsaturated Pd sites (Pdcus). Weak binding of CO on Pdcus sites in small Pd NPs leaving sites for oxygen activation is attributed to the low temperature activity of Pd-S-N for CO oxidation.
ISSN:0926-3373
1873-3883
DOI:10.1016/j.apcatb.2020.118934