DFT calculations on selectivity enhancement by Br addition on Pd catalysts in the direct synthesis of hydrogen peroxide

Min Woo Lee, Deok Yeon Jo, Geun Ho Han, Kwan Young Lee

Research output: Contribution to journalArticlepeer-review

Abstract

Although the direct synthesis of hydrogen peroxide (DSHP) is a potential alternative to the current anthraquinone auto-oxidation process, the low H2O2 selectivity of the former presents a major challenge. Previous studies have reported that the addition of halides improves the H2O2 selectivity of Pd-based catalysts. In this study, the H2O2 selectivity of Pd/SiO2 and PdBrx/SiO2 catalysts was observed to increase with the Br content. Furthermore, density functional theory (DFT) calculations on clean and Br-adsorbed Pd (1 1 1), (1 0 0), and (2 1 1) surfaces confirmed that the activation energies of the side reactions on the Pd (1 1 1) surface increased slightly after Br adsorption, whereas those of the main reactions were less affected. The repulsion between Br and O on the Pd (1 0 0) surface increased the O2 dissociation barrier by changing reaction configurations. Considering that the Pd (1 0 0) surface adsorbed O2 more strongly than did the Pd (1 1 1) surface, inhibiting O2 dissociation on the Pd (1 0 0) surface improved the H2O2 selectivity of PdBrx/SiO2 catalysts. On the Pd (2 1 1) surface, Br blocked an edge site and induced the reactions on the Pd (1 1 1) surface. In conclusion, DFT calculation confirmed that the repulsion and site blocking by adsorbed Br improved the H2O2 selectivity of PdBrx/SiO2 catalysts.

Original languageEnglish
Pages (from-to)232-239
Number of pages8
JournalCatalysis Today
Volume397-399
DOIs
Publication statusPublished - 2022 Aug 1

Keywords

  • Density functional theory
  • Halide addition
  • Hydrogen peroxide
  • Palladium
  • Surface modification

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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