Gold particle size effects in the gas-phase hydrogenation of m-dinitrobenzene over Au/TiO2

Fernando Cardenas-Lizana, Santiago Gomez-Quero, Hicham Idriss, Mark A. Keane

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76 Citations (Scopus)

Abstract

The effect of Au particle size, supported on TiO2, on the gas-phase hydrogenation of m-dinitrobenzene has been considered. The catalysts (Au loading = 0.1 and 1 mol%) were prepared by impregnation with HAuCl4 and a range of Au particle sizes (3.4-10.0 nm) was generated by temperature-programmed reduction over the interval 603 K = T = 1273 K. A thermal treatment of TiO2 at T = 873 K was required for the allotropic change from anatase to rutile but the presence of Au lowered the requisite temperature for complete transformation by up to 400 K. m-Dinitrobenzene hydrogenation exhibited a particle size sensitivity where higher specific rates were obtained with smaller Au particles, irrespective of the support composition (i.e. anatase:rutile ratio). The reaction over each Au/TiO2 catalyst generated m-phenylenediamine (reduction of both -NO2 groups) and/or m-nitroaniline (reduction of one -NO2 group). A parallel/ consecutive kinetic model has been applied to quantify the catalytic selectivity where Au particles <5 nm favoured m-nitroaniline production. The dependence of hydrogenation performance on Au particle size is accounted for in terms of a modification to Au electronic character, which impacts on m-dinitrobenzene adsorption/activation. © 2009 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)223-234
Number of pages12
JournalJournal of Catalysis
Volume268
Issue number2
DOIs
Publication statusPublished - 10 Dec 2009

Keywords

  • Anatase
  • Au particle size
  • Au/TiO 2
  • M-Dinitrobenzene hydrogenation
  • Rutile

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