The active oxygen species promoted catalytic oxidation of 5-hydroxymethyl-2-furfural on facet-specific Pt nanocrystals

Yaqi Liu, Hong-Yan Ma, Da Lei, Lan-Lan Lou, Shuangxi Liu, Wuzong Zhou, Gui-Chang Wang, Kai Yu

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Abstract

The aerobic oxidation of alcohols and aldehydes over noble metal catalysts is a critical reaction for the catalytic conversion of carbohydrates into value-added chemicals from biomass. However, to fully understand the reaction mechanism, in particular the role of O2 and the generated active oxygen species in these reactions is still a challenging target. In the present work, the sub-10 nm Pt nanocrystals with cubic (Pt-NCs), octahedral (Pt-NOs) and spherical (Pt-NSs) morphologies were synthesized and used as catalysts in aerobic oxidation of HMF. Through experimental and computational investigations, the facet-dependent O2 conversion pathway and catalytic oxidation performance were discussed. The molecular O2 tends to be dissoci-ated to generate •OH on Pt(100) surface, but prefers to be reduced to •O2- on Pt(111) surface. Moreover, Pt-NCs enclosed by the {100} facets exhibited significantly enhanced catalytic activity than Pt-NOs enclosed by the {111} facets and Pt-NSs, in particular for alcohol oxidation step. Based on the experimental data and density functional theory (DFT) calculations, an active oxygen species promoted dehydrogenation mechanism for aerobic oxidation of HMF was proposed. The dehydrogena-tion of alcohol group is more favourable on the Pt(100) surface with an assistance of •OH, which are the dominant active oxygen species on the Pt(100) surface. We anticipate that this work would provide a new insight into the role of active oxy-gen species in aerobic oxidation of alcohols and aldehydes over noble metal catalysts.
Original languageEnglish
Pages (from-to)8306-8315
JournalACS Catalysis
Volume9
Issue number9
Early online date29 Jul 2019
DOIs
Publication statusPublished - 6 Sept 2019

Keywords

  • Pt nanocrystals
  • Active oxygen species
  • Aerobic oxidation of HMF
  • DFT calculations
  • Facet-dependent performance

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