Structural properties and catalytic activity in selective oxidation of In-containing ZSM-5 catalysts

János Halász, Wanda Nyári, Edit Mereteia, István Hannus, János B. Nagy, Imre Kiricsi

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Abstract

The characteristics of In-containing ZSM-5 zeolites prepared by different method have been investigated in the correlation of catalytic activity in the oxidative reaction of pentane and hexane. The zeolite catalysts have been prepared using four different methods: (i) ion-exchange in In(NO3)3 solution; (ii) solid state ion-exchange in oxidative atmosphere; (iii) solid state ion-exchange in reductive atmosphere; (iv) isomorphous substitution of aluminum for indium in the synthesis. The catalysts have been characterized by thermal analytical, XRD, nitrogen adsorption, IR, UV-VIS, 29Si MAS NMR, 27Al MAS NMR spectroscopic methods. Conversion of n-pentane and n-hexane has been studied in a fixed bed flow reactor in the presence or in the absence of dioxygen. High cracking activity is characteristic of the catalysts with high surface Brönsted acidity due to the oxidative treatment, while the catalyst pre-treated in reductive atmosphere having Lewis acidity are effective in the dehydrogenation and aromatization reactions of pentane and hexane. However, the significant increase of aromatic selectivity in the case of the catalyst prepared by solid state ion-exchange could be accounted to rapid dehydrogenation caused by isolated In2O particles formed in reductive atmosphere. Synergism, namely intimate contact between these particles and the framework silicate structure can be assumed as active sites for the dehydrogenation and aromatization of alkenes.

Original languageEnglish
Pages (from-to)315-322
Number of pages8
JournalJournal of Molecular Structure
Volume651-653
DOIs
Publication statusPublished - Jun 1 2003

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Keywords

  • In -ZSM-5 zeolites
  • Paraffins oxidation
  • Solid state ion-exchange

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry
  • Inorganic Chemistry

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