Effects of varying amounts of Na on Pd/TiO2 for the direct synthesis of H2O2: Identification of the Pd dispersion and catalytic activity enhancement by changing the surface electronic states

Young Hoon Cho, Geun Ho Han, Sang Soo Han, Myung gi Seo, Kwan Young Lee

Research output: Contribution to journalArticle

Abstract

Alkali elements have been applied as promoters of noble metals (e.g., Pd or Pt) to enhance their catalytic activities by changing the surface electronic states of the noble metals. In particular, the role of alkali elements is to improve the dispersion properties of the active metal. In this study, various amounts of the alkali element sodium (Na) were used as a promoter for a Pd/TiO2 catalyst. Importantly, the catalysts were synthesized to improve the selectivity and production rate of the direct synthesis of hydrogen peroxide (DSHP) by increasing the Pd dispersion and surface area by changing the surface electronic properties. After the addition of Na onto Pd/TiO2, the H2O2 production rates were generally higher than those for pure Pd/TiO2 due to the synergistic effects between the Pd and Na on the TiO2 support. Particularly, among the tested catalysts, the 0.5 wt.% Na-promoted Pd/TiO2 (PdNa(0.6)/TiO2) catalyst exhibited the highest H2 conversion rate (22 %) in the iso-Pd weight and the highest H2O2 selectivity (95.4 %) and production rate (785.9 mmol/gPdh) for the iso-H2 conversion test. Na provides electrons to the Pd species, leading to a change in the Pd dispersion. Furthermore, the surface electronic state of Pd changed with increasing amounts of Na, and thus, heavily influenced the H2O2 selectivity. Ultimately, PdNa(0.6)/TiO2 achieved the best selectivity as a H2O2 producing catalyst in this study.

Original languageEnglish
Article number110732
JournalMolecular Catalysis
DOIs
Publication statusAccepted/In press - 2019 Jan 1

Fingerprint

Electronic states
catalytic activity
Catalyst activity
Alkalies
catalysts
Catalysts
selectivity
augmentation
synthesis
alkalies
electronics
Catalyst selectivity
Precious metals
noble metals
hydrogen peroxide
Catalyst supports
Hydrogen peroxide
Electronic properties
Hydrogen Peroxide
Metals

Keywords

  • Alkali metal
  • Direct synthesis of hydrogen peroxide
  • Highly Pd dispersion
  • Palladium
  • Sodium addition
  • Titanium dioxide

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology
  • Physical and Theoretical Chemistry

Cite this

@article{35acdabadac14fa48228af0cfeb01abc,
title = "Effects of varying amounts of Na on Pd/TiO2 for the direct synthesis of H2O2: Identification of the Pd dispersion and catalytic activity enhancement by changing the surface electronic states",
abstract = "Alkali elements have been applied as promoters of noble metals (e.g., Pd or Pt) to enhance their catalytic activities by changing the surface electronic states of the noble metals. In particular, the role of alkali elements is to improve the dispersion properties of the active metal. In this study, various amounts of the alkali element sodium (Na) were used as a promoter for a Pd/TiO2 catalyst. Importantly, the catalysts were synthesized to improve the selectivity and production rate of the direct synthesis of hydrogen peroxide (DSHP) by increasing the Pd dispersion and surface area by changing the surface electronic properties. After the addition of Na onto Pd/TiO2, the H2O2 production rates were generally higher than those for pure Pd/TiO2 due to the synergistic effects between the Pd and Na on the TiO2 support. Particularly, among the tested catalysts, the 0.5 wt.{\%} Na-promoted Pd/TiO2 (PdNa(0.6)/TiO2) catalyst exhibited the highest H2 conversion rate (22 {\%}) in the iso-Pd weight and the highest H2O2 selectivity (95.4 {\%}) and production rate (785.9 mmol/gPdh) for the iso-H2 conversion test. Na provides electrons to the Pd species, leading to a change in the Pd dispersion. Furthermore, the surface electronic state of Pd changed with increasing amounts of Na, and thus, heavily influenced the H2O2 selectivity. Ultimately, PdNa(0.6)/TiO2 achieved the best selectivity as a H2O2 producing catalyst in this study.",
keywords = "Alkali metal, Direct synthesis of hydrogen peroxide, Highly Pd dispersion, Palladium, Sodium addition, Titanium dioxide",
author = "Cho, {Young Hoon} and Han, {Geun Ho} and Han, {Sang Soo} and Seo, {Myung gi} and Lee, {Kwan Young}",
year = "2019",
month = "1",
day = "1",
doi = "10.1016/j.mcat.2019.110732",
language = "English",
journal = "Molecular Catalysis",
issn = "2468-8231",
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}

TY - JOUR

T1 - Effects of varying amounts of Na on Pd/TiO2 for the direct synthesis of H2O2

T2 - Identification of the Pd dispersion and catalytic activity enhancement by changing the surface electronic states

AU - Cho, Young Hoon

AU - Han, Geun Ho

AU - Han, Sang Soo

AU - Seo, Myung gi

AU - Lee, Kwan Young

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Alkali elements have been applied as promoters of noble metals (e.g., Pd or Pt) to enhance their catalytic activities by changing the surface electronic states of the noble metals. In particular, the role of alkali elements is to improve the dispersion properties of the active metal. In this study, various amounts of the alkali element sodium (Na) were used as a promoter for a Pd/TiO2 catalyst. Importantly, the catalysts were synthesized to improve the selectivity and production rate of the direct synthesis of hydrogen peroxide (DSHP) by increasing the Pd dispersion and surface area by changing the surface electronic properties. After the addition of Na onto Pd/TiO2, the H2O2 production rates were generally higher than those for pure Pd/TiO2 due to the synergistic effects between the Pd and Na on the TiO2 support. Particularly, among the tested catalysts, the 0.5 wt.% Na-promoted Pd/TiO2 (PdNa(0.6)/TiO2) catalyst exhibited the highest H2 conversion rate (22 %) in the iso-Pd weight and the highest H2O2 selectivity (95.4 %) and production rate (785.9 mmol/gPdh) for the iso-H2 conversion test. Na provides electrons to the Pd species, leading to a change in the Pd dispersion. Furthermore, the surface electronic state of Pd changed with increasing amounts of Na, and thus, heavily influenced the H2O2 selectivity. Ultimately, PdNa(0.6)/TiO2 achieved the best selectivity as a H2O2 producing catalyst in this study.

AB - Alkali elements have been applied as promoters of noble metals (e.g., Pd or Pt) to enhance their catalytic activities by changing the surface electronic states of the noble metals. In particular, the role of alkali elements is to improve the dispersion properties of the active metal. In this study, various amounts of the alkali element sodium (Na) were used as a promoter for a Pd/TiO2 catalyst. Importantly, the catalysts were synthesized to improve the selectivity and production rate of the direct synthesis of hydrogen peroxide (DSHP) by increasing the Pd dispersion and surface area by changing the surface electronic properties. After the addition of Na onto Pd/TiO2, the H2O2 production rates were generally higher than those for pure Pd/TiO2 due to the synergistic effects between the Pd and Na on the TiO2 support. Particularly, among the tested catalysts, the 0.5 wt.% Na-promoted Pd/TiO2 (PdNa(0.6)/TiO2) catalyst exhibited the highest H2 conversion rate (22 %) in the iso-Pd weight and the highest H2O2 selectivity (95.4 %) and production rate (785.9 mmol/gPdh) for the iso-H2 conversion test. Na provides electrons to the Pd species, leading to a change in the Pd dispersion. Furthermore, the surface electronic state of Pd changed with increasing amounts of Na, and thus, heavily influenced the H2O2 selectivity. Ultimately, PdNa(0.6)/TiO2 achieved the best selectivity as a H2O2 producing catalyst in this study.

KW - Alkali metal

KW - Direct synthesis of hydrogen peroxide

KW - Highly Pd dispersion

KW - Palladium

KW - Sodium addition

KW - Titanium dioxide

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