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Issue 27, 2007
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Activation and isomerization of n-butane on sulfated zirconia model systems—an integrated study across the materials and pressure gaps

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Abstract

Butane activation has been studied using three types of sulfated zirconia materials, single crystalline epitaxial films, nanocrystalline films, and powders. A surface phase diagram of zirconia in interaction with SO3 and water was established by DFT calculations, which was verified by LEED investigations on single-crystalline films and by IR spectroscopy on powders. At high sulfate surface densities a pyrosulfate species is the prevailing structure in the dehydrated state; if such species are absent, the materials are inactive. Theory and experiment show that the pyrosulfate can react with butane to give butene, H2O and SO2, hence butane can be activated via oxidative dehydrogenation. This reaction occurred on all investigated materials; however, isomerization could only be proven for powders. Transient and equilibrium adsorption measurements in a wide pressure and temperature range (isobars measured via UPS on nanocrystalline films, microcalorimetry and temporal analysis of products measurements on powders) show weak and reversible interaction of butane with a majority of sites but reactive interaction with <5 μmol g−1 sites. Consistently, the catalysts could be poisoned by adding sodium to the surface in a ratio S/Na = 35. Future research will have to clarify what distinguishes these few sites.

Graphical abstract: Activation and isomerization of n-butane on sulfated zirconia model systems—an integrated study across the materials and pressure gaps

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Publication details

The article was received on 06 Feb 2007, accepted on 11 May 2007 and first published on 01 Jun 2007


Article type: Paper
DOI: 10.1039/B701854A
Citation: Phys. Chem. Chem. Phys., 2007,9, 3600-3618
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    Activation and isomerization of n-butane on sulfated zirconia model systems—an integrated study across the materials and pressure gaps

    C. Breitkopf, H. Papp, X. Li, R. Olindo, J. A. Lercher, R. Lloyd, S. Wrabetz, F. C. Jentoft, K. Meinel, S. Förster, K.-M. Schindler, H. Neddermeyer, W. Widdra, A. Hofmann and J. Sauer, Phys. Chem. Chem. Phys., 2007, 9, 3600
    DOI: 10.1039/B701854A

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