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Tunable gas phase hydrogenation of m-dinitrobenzene over alumina supported Au and Au–Ni

Paper ID Volume ID Publish Year Pages File Format Full-Text
41799 45900 2010 11 PDF Available
Title
Tunable gas phase hydrogenation of m-dinitrobenzene over alumina supported Au and Au–Ni
Abstract

The gas phase hydrogenation of m-dinitrobenzene (m-DNB) has been investigated over alumina supported Au (1 mol%), Ni (10 mol%) and Au–Ni (Au/Ni mol ratio = 1/10). Au/Al2O3 delivered a time invariant exclusive formation of m-nitroaniline (partial reduction), Ni/Al2O3 promoted total nitro-group reduction to give m-phenylenediamine as the sole product and Au–Ni/Al2O3 generated both products (partial and complete hydrogenation); Ni/Al2O3 and Au–Ni/Al2O3 exhibited a temporal decline in activity. A physical mixture of Au/Al2O3 + Ni/Al2O3 delivered a hydrogenation rate and product composition that was equivalent to that obtained with Ni/Al2O3, i.e. Au/Al2O3 had a negligible contribution to the catalytic process, which was governed by the Ni component in the mixture. The catalysts have been characterized in terms of temperature-programmed reduction (TPR), H2 chemisorption/temperature-programmed desorption (TPD), BET area/pore volume, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV–vis (DRS UV–vis) and HRTEM-EDX measurements. The presence of zero valent Au and Ni is established post-TPR where EDX mapping has revealed a close surface proximity of both metals (mean particle size = 9 nm) in Au–Ni/Al2O3 with evidence (from XPS) of electron donation from Ni to Au. While the addition of Au to Ni/Al2O3 served to suppress H2 chemisorption post-TPR, H2-TPD revealed a more facile release of a greater amount of hydrogen from Au–Ni/Al2O3 relative to Ni/Al2O3, which we attribute to surface Au–Ni interaction that is also manifest in the hydrogenation activity/selectivity response. Our results establish the feasibility of controlling product distribution through the application of mono- (Au or Ni) and bimetallic (Au–Ni) catalysts.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (62 K)Download as PowerPoint slideResearch highlights▶ Au–Ni/Al2O3 prepared by the reductive deposition of Au onto Ni. ▶ Exclusive m-dinitrobenzene → m-nitroaniline (partial reduction) over Au/Al2O3. ▶ Exclusive m-dinitrobenzene → m-phenylenediamine (complete reduction) over Ni/Al2O3. ▶ Au–Ni/Al2O3 promotes both partial and complete hydrogenation.

Keywords
Selective hydrogenation; m-Dinitrobenzene; Reductive deposition of Au on Ni; Au/Al2O3; Ni/Al2O3; Au–Ni/Al2O3
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Tunable gas phase hydrogenation of m-dinitrobenzene over alumina supported Au and Au–Ni
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 387, Issues 1–2, 20 October 2010, Pages 155–165
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