Coverage Effects on the Palladium-Catalyzed Synthesis of Vinyl Acetate: Comparison between Theory and Experiment.
The high adsorbate coverages that form on the surfaces of many heterogeneous catalysts under steady-state conditions can significantly lower the activation energies for reactions that involve the coupling of two adsorbed intermediates while increasing those which result in adsorbate bond-breaking re...
| Publicado en: | Journal of the American Chemical Society Vol. 132; no. 7; pp. 2202 - 2208 |
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| Autores principales: | , , , |
| Formato: | Artículo |
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American Chemical Society
2/24/2010
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=48616425&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 48616425 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 2/24/2010 vid: 132 iid: 7 pid: 997 pub: American Chemical Society artinfo: ui: 48616425 10.1021/ja907061m ppf: 2202 ppct: 6 formats: tig: atl: Coverage Effects on the Palladium-Catalyzed Synthesis of Vinyl Acetate: Comparison between Theory and Experiment. aug: au: Calaza, Florencia Stacchiola, Dario Neurock, Matthew Tysoe, Wilfred T. affil: Department of Chemistry and Biochemistry, Laboratory for Surface Studies, Universily of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211 Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931 Departments of Chemical Engineering and Chemistry, University of Virginia, Charlottesville, Virginia 22904-4 741 su: Heterogeneous catalysis Metal catalysts Vinyl acetate Ultrahigh vacuum Density functionals Volumetric analysis sug: subj: Heterogeneous catalysis Metal catalysts Vinyl acetate Ultrahigh vacuum Density functionals Volumetric analysis ab: The high adsorbate coverages that form on the surfaces of many heterogeneous catalysts under steady-state conditions can significantly lower the activation energies for reactions that involve the coupling of two adsorbed intermediates while increasing those which result in adsorbate bond-breaking reactions. The influence of the surface coverage on the kinetics of metal-catalyzed reactions is often ignored in theoretical and even in some ultrahigh vacuum experimental studies. Herein, first principle density functional theoretical calculations are combined with experimental surface titration studies carried out over well-defined Pd(111) surfaces to explicitly examine the influence of coverage on the acetoxylation of ethylene to form vinyl acetate over Pd. The activation energies calculated for elementary steps in the Samanos and Moiseev pathways for vinyl acetate synthesis carried out on acetate-saturated palladium surfaces reveal that the reaction proceeds via the Samanos mechanism which is consistent with experimental results carried out on acetate-saturated Pd(111) surfaces. The rate-limiting step involves a β-hydride elimination from the adsorbed acetoxyethyl intermediate, which proceeds with an apparent calculated activation barrier of 53 kJ/mol which is in very good agreement with the experimental barrier of 55 ± 4 kJ/mol determined from kinetic measurements. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2010 holdings: @attributes: islocal: N |
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