Kinetics study of hydrogen adsorption over Pt/MoO3

Sugeng Triwahyono, Aishah Abdul Jalil, Timmiati Sharifah Najiha, Nurun Najwa Ruslan, Hideshi Hattori

Research output: Contribution to journalArticle

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Abstract

The rate controlling step and the energy barrier involved in the hydrogen adsorption over Pt/MoO3 were studied. Rates of hydrogen adsorption on Pt/MoO3 were measured at the adsorption temperature range of 323-573 K and at the initial hydrogen pressure of 6.7 kPa. The rate of hydrogen uptake was very high for the initial few minutes for adsorption at and above 473 K, and reached equilibrium within 2 h. At and below 423 K, the hydrogen uptake still continued and did not reach equilibrium after 10 h. The hydrogen uptake exceeded the H/Pt ratio of unity for adsorption at and above 423 K, indicating that hydrogen adsorption involves hydrogen atom spillover and surface diffusion of the spiltover hydrogen atom over the bulk surface of MoO3 followed by formation of HxMoO3. The hydrogen uptake was scarcely appreciable for Pt-free MoO3. The rate controlling step of the hydrogen adsorption on Pt/MoO3 was the surface diffusion of the spiltover hydrogen with the activation energy of 83.1 kJ/mol. The isosteric heats of hydrogen adsorption on Pt/MoO3 were 18.1-16.9 kJ/mol for the hydrogen uptake range 2.4-2.8 × 1019 H-atom/g-cat. Similarities and differences in hydrogen adsorption on Pt/SO4 2--ZrO2, Pt/WO3-ZrO2 and Pt/MoO3 catalysts are discussed.

Original languageEnglish
Pages (from-to)103-107
Number of pages5
JournalApplied Catalysis A: General
Volume372
Issue number1
DOIs
Publication statusPublished - 5 Jan 2010
Externally publishedYes

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Hydrogen
Adsorption
Kinetics
Surface diffusion
molybdenum trioxide
Atoms
Energy barriers
Activation energy

Keywords

  • HMoO
  • Heat adsorption
  • Hydrogen adsorption
  • Pt/MoO
  • Surface diffusion

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

Cite this

Kinetics study of hydrogen adsorption over Pt/MoO3 . / Triwahyono, Sugeng; Jalil, Aishah Abdul; Sharifah Najiha, Timmiati; Ruslan, Nurun Najwa; Hattori, Hideshi.

In: Applied Catalysis A: General, Vol. 372, No. 1, 05.01.2010, p. 103-107.

Research output: Contribution to journalArticle

Triwahyono, Sugeng ; Jalil, Aishah Abdul ; Sharifah Najiha, Timmiati ; Ruslan, Nurun Najwa ; Hattori, Hideshi. / Kinetics study of hydrogen adsorption over Pt/MoO3 In: Applied Catalysis A: General. 2010 ; Vol. 372, No. 1. pp. 103-107.
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