Unique selectivity in the hydrodechlorination of 2,4-dichlorophenol over hematite-supported Au

Santiago Gomez Quero, Fernando Cardenas-Lizana, Mark A Keane

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

The gas-phase hydrodechlorination of 2,4-dichlorophenol (at 423 K) has been studied over Au/Fe2O3 prepared by deposition-precipitation. Support and catalyst were characterised by TPR, XRD, H-2 chemisorption/TPD, BET area/porosity and TEM/SEM measurements. Fe2O3 was reduced to Fe3O4 and Fe following TPR to 673 K and 1273 K, respectively; inclusion of Au lowered (by 200 K) support reduction temperature. TPR of Au/Fe2O3 to 423 K generated quasi-spherical Au particles (mean size = 2.6 nm) that promoted hydrogenolysis of ortho-Cl, generating 4-chlorophenol via a stepwise mechanism. We attribute this unprecedented selectivity to reactant interaction through -OH at electron-deficient Au sites, rendering ortho-CI susceptible to attack. Solvent effects are demonstrated for a range of carriers where conversion of aqueous 2,4-DCP delivered the highest rate (1 x 10(-3) mol(CI) h(-1) m(Au)(-2)), equivalent to that achieved with Ni/SiO2 at 573 K. Selectivity in the cleavage of sterically constrained Cl in mono-, di- and tri-chlorophenols is also demonstrated. (c) 2013 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)41-49
Number of pages9
JournalJournal of Catalysis
Volume303
DOIs
Publication statusPublished - Jul 2013

Keywords

  • Chlorophenol(s)
  • Selective hydrodechlorination
  • Au/Fe2O3
  • 2,4-Dichlorophenol
  • Inductive effects
  • GAS SHIFT REACTION
  • PHASE CATALYTIC HYDRODECHLORINATION
  • LOW-TEMPERATURE REDUCTION
  • GOLD CATALYSTS
  • CO OXIDATION
  • IRON-OXIDES
  • DEPOSITION-PRECIPITATION
  • HETEROGENEOUS CATALYSTS
  • PALLADIUM CATALYSTS
  • AU/FE2O3 CATALYSTS

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