Chromium sites in zeolite framework: Chromyl or chromium hydroxyl groups?

Frederik Tielens, Mazharul M. Islam, Gabriella Skara, Frank De Proft, Tetsuya Shishido, Stanislaw Dzwigaj

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

A combined experimental and ab initio periodic DFT calculation on the structure and stability of different chromium-substituted zeolite models are presented. Experimental investigation by XRD, FT-IR and UV-vis show the presence of chromium in SiBEA zeolite. The favorable chromium sites are characterized by their calculated geometrical parameters, energetics, vibrational frequencies and protonation/deprotonation energies. The theoretical vibrational frequencies are compared with experimental FT-IR measurements. A phase diagram was constructed on the basis of calculated total energies of the optimized structures. Cr(III) is stabilized in the zeolite framework as a tri-coordinated site. Cr sites are predicted to be more acidic than group V containing zeolites. Dehydration of the site leads to the formation of a Cr(VI) containing a CrO group. These results are fully consistent with experimental data and allow the identification of the molecular structure of chromium sites in a zeolite framework.

Original languageEnglish
Pages (from-to)66-73
Number of pages8
JournalMicroporous and Mesoporous Materials
Volume159
Early online date11 Apr 2012
DOIs
Publication statusPublished - 1 Sep 2012

Keywords

  • Chromium
  • DR UV-vis
  • FT-IR
  • Periodic DFT
  • Zeolite

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials

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