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Kinetics study of hydrogen adsorption over Pt/MoO3

Paper ID Volume ID Publish Year Pages File Format Full-Text
42374 45922 2010 5 PDF Available
Title
Kinetics study of hydrogen adsorption over Pt/MoO3
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/SO42−–ZrO2, Pt/WO3–ZrO2 and Pt/MoO3 catalysts are discussed.

Graphical abstractThe hydrogen adsorption on Pt/MoO3 involves the dissociation of hydrogen molecules to hydrogen atoms, spillover of the dissociated hydrogen onto the surface of MoO3, surface diffusion of the spiltover hydrogen over the bulk surface of MoO3 and formation of HxMoO3. The rate controlling step is surface diffusion of spiltover hydrogen atom with the activation energy of 83.1 kJ/mol.Figure optionsDownload full-size imageDownload high-quality image (65 K)Download as PowerPoint slide

Keywords
Pt/MoO3; Hydrogen adsorption; HxMoO3; Surface diffusion; Heat adsorption
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 372, Issue 1, 5 January 2010, Pages 103–107
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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