Catalytic Anisotropy of MoO3 in the Oxidative Ammonolysis of Toluene

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Abstract

The oxidative ammonolysis of toluene, i.e., ammoxidation without the presence of molecular oxygen, was studied over a series of samples of MoO3 crystals. The specific surface areas of the various faces were determined from SEM micrographs. Correlations between activities and surface planes were found. For the formation of nitrile the specific activity decreased in the order {001} and {h01} > {100} > {010}. Also, for the formation of carbon oxides the terminations in the [001] direction were found to be especially active. These results are discussed in relation to surface structures and bond strength values of various oxygen species. It is concluded that the presence of both oxygen vacancies and nucleophilic oxygen species is a prerequisite for selective reaction to occur and that electrophilic oxygen species are the source for formation of carbon oxides. The characteristics of the various faces, as they emerge from the results on oxidative ammonolysis of toluene, seem to be of general significance for reactions occurring at the same types of active sites. They are shown to be applicable to results published in the literature on the oxidation of both propene and isobutene.

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  • Chemical Engineering
Original languageEnglish
Pages (from-to)332-346
JournalJournal of Catalysis
Volume114
Issue number2
Publication statusPublished - 1988
Publication categoryResearch
Peer-reviewedYes