Selective side-chain oxidation of alkyl aromatic compounds catalyzed by cerium modified silver catalysts

Matthias J. Beier, Bjoern Schimmoeller, Thomas W. Hansen, Jens E.T. Andersen, Sotiris E. Pratsinis, Jan Dierk Grunwaldt

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Silver supported on silica effectively catalyzes the aerobic side-chain oxidation of alkyl aromatic compounds under solvent-free conditions. Toluene, p-xylene, ethylbenzene and cumene were investigated as model substrates. Typically, the reaction was performed at ambient pressure; only for toluene an elevated pressure was required. Carboxylic acids, such as benzoic acid or p-toluic acid, additionally increased the reaction rate while CeO2 could act both as a promoter and an inhibitor depending on the substrate and the reaction conditions. Silver catalysts were prepared both by standard impregnation and flame spray pyrolysis. Addition of a Ce precursor to the FSP catalyst resulted in significantly smaller silver particles. Ce-doped FSP catalysts in general exhibited a superior catalytic performance with TONs up to 2000 except for cumene oxidation that appeared to proceed mainly by homogeneous catalysis. In addition, flame-made catalysts were more stable against silver leaching compared to the impregnated catalysts. The structure of the silver catalysts was studied in detail both by X-ray absorption spectroscopy and transmission electron microscopy suggesting metallic silver to be required for catalytic activity. Catalytic studies point to a radical mechanism which differs depending on the type of substrate.

Original languageEnglish
Pages (from-to)40-49
Number of pages10
JournalJournal of Molecular Catalysis A: Chemical
Volume331
Issue number1-2
DOIs
Publication statusPublished - Oct 1 2010

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Process Chemistry and Technology
  • Physical and Theoretical Chemistry

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