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Effect of the sequence of impregnation on the activity and sulfur resistance of Pt–Ni/γ-Al2O3 bimetallic catalysts for the selective hydrogenation of styrene

Paper ID Volume ID Publish Year Pages File Format Full-Text
40832 45867 2012 6 PDF Available
Title
Effect of the sequence of impregnation on the activity and sulfur resistance of Pt–Ni/γ-Al2O3 bimetallic catalysts for the selective hydrogenation of styrene
Abstract

The influence of the preparation of bimetallic Pt–Ni catalysts on their activity and sulfur resistance during styrene semi-hydrogenation was studied. The preparation variables assessed were the sequence of impregnation and the kind of nickel precursor used. The catalysts were tested with the styrene hydrogenation reaction and further characterized by ICP, TPR, XPS and pyridine TPD.All catalysts showed high selectivities to ethylbenzene (>98%). The bimetallic catalysts were more active than monometallic Pt and the following activity order was found: Pt ≅ NiClPt ≤ NiNPt < PtNiCl < PtNiN. After poisoning with 300 ppm of thiophene the following order of sulfur resistance was found: PtNiCl < Pt ≪ PtNiN ≅ NiClPt ≅ NiNPt.Differences in activity and sulfur resistance between the catalysts were attributed to electronic effects, in turn related to the presence of different electron-rich and electron-deficient surface species of Pt and Ni interacting between themselves and with the support. The bimetallic catalyst with the highest Cl/Pt atomic ratio on the surface (as obtained by XPS) proved to be the most sulfur resistant; this higher poison resistance was rationalized in terms of both steric and electronic effects.

Graphical abstractStyrene total conversion as a function of time in the absence of poison. () Pt, () NiClPt, () NiNPt, () PtNiCl and () PtNiN.Figure optionsDownload full-size imageDownload high-quality image (68 K)Download as PowerPoint slideFigure optionsDownload full-size imageDownload high-quality image (<1 K)Download as PowerPoint slideFigure optionsDownload full-size imageDownload high-quality image (0 K)Download as PowerPoint slideFigure optionsDownload full-size imageDownload high-quality image (<1 K)Download as PowerPoint slideFigure optionsDownload full-size imageDownload high-quality image (<1 K)Download as PowerPoint slideFigure optionsDownload full-size imageDownload high-quality image (<1 K)Download as PowerPoint slideHighlights► Low-loaded Pt and Ni bimetallic catalysts were prepared. ► Elenctron-rich species of Ptδ− were found by XPS on the bimetallic catalysts. ► Due to an electronic effect, PtNi and NiPt were more active than monometallic Pt. ► NiPt catalysts were more sulfur resistant because of steric and electronic effects. ► Species of Ni0 and Ptδ− on PtNiCl are responsible of poisoning.

Keywords
Selective hydrogenation; Bimetallic catalysts; Sulfur resistance; Platinum; Nickel
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Effect of the sequence of impregnation on the activity and sulfur resistance of Pt–Ni/γ-Al2O3 bimetallic catalysts for the selective hydrogenation of styrene
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 435–436, 5 September 2012, Pages 181–186
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
Online Support
Any Questions? feel free to contact us