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Effect of Crystallographic Phase (β vs. γ) and Surface Area on Gas Phase Nitroarene Hydrogenation Over Mo2N and Au/Mo2N

Perret, Noémie ; Cárdenas-Lizana, Fernando ; Lamey, Daniel ; Laporte, Vincent ; Kiwi-Minsker, Lioubov ; Keane, Mark

In: Topics in Catalysis, 2012, vol. 55, no. 14-15, p. 955-968

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    Titre
    • Effect of Crystallographic Phase (β vs. γ) and Surface Area on Gas Phase Nitroarene Hydrogenation Over Mo2N and Au/Mo2N
    Auteur
    • Perret, Noémie. Chemical Engineering, School of Engineering and Physical Sciences, Heriot-Watt University, EH14 4AS, Edinburgh, Scotland, UK
    • Cárdenas-Lizana, Fernando. Group of Chemical Reaction Engineering, Ecole Polytechnique Fédérale de Lausanne, GGRC-ISIC-EPFL, Station 6, 1015, Lausanne, Switzerland
    • Lamey, Daniel. Group of Chemical Reaction Engineering, Ecole Polytechnique Fédérale de Lausanne, GGRC-ISIC-EPFL, Station 6, 1015, Lausanne, Switzerland
    • Laporte, Vincent. Interdisciplinary Centre for Electron Microscopy, Ecole Polytechnique Fédérale de Lausanne, Station 12, 1015, Lausanne, Switzerland
    • Kiwi-Minsker, Lioubov. Group of Chemical Reaction Engineering, Ecole Polytechnique Fédérale de Lausanne, GGRC-ISIC-EPFL, Station 6, 1015, Lausanne, Switzerland
    • Keane, Mark. Chemical Engineering, School of Engineering and Physical Sciences, Heriot-Watt University, EH14 4AS, Edinburgh, Scotland, UK
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Topics in Catalysis, 2012, vol. 55, no. 14-15, p. 955-968. Springer US; http://www.springer-ny.com
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:314673
    Summary
    The catalytic action of Mo2N and Au/Mo2N has been assessed in the selective gas phase hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). The nitrides were synthesised via temperature programmed treatment of MoO3 in H2+N2 and Au introduced by deposition-precipitation with urea. We have examined the influence of nitride crystallographic phase (tetragonal β-Mo2N vs. cubic γ-Mo2N) and surface area (7-66m2g−1) on the catalytic response. Catalyst activation by temperature programmed reduction has been monitored and the reduced catalysts characterised in terms of BET area/pore volume, H2 chemisorption/temperature programmed desorption (TPD), powder X-ray diffraction (XRD), elemental analysis, scanning (SEM) and transmission (TEM) electron microscopy and X-ray photoelectron spectroscopy (XPS) measurements. The formation of β- and γ-Mo2N was confirmed by XRD and TEM. γ-Mo2N exhibits a platelet morphology whereas β-Mo2N is characterised by an aggregation of small crystallites. Hydrogen chemisorption and TPD analysis have established a greater hydrogen uptake capacity (per unit area) for β-Mo2N relative to γ-Mo2N, which is associated with surface nitrogen deficiency, i.e. higher surface Mo/N for β-Mo2N. Incorporation of Au on both nitrides resulted in an increase in surface hydrogen. The Au phase takes the form of nano-scale particles with a mean size of 7 and 4nm on β-Mo2N and γ-Mo2N, respectively. Both β-Mo2N and γ-Mo2N promoted the exclusive hydrogenation of p-CNB to p-CAN where the β-form delivered a higher specific (per m2) rate; the specific rate for γ-Mo2N was independent of surface area. The inclusion of Au on both nitrides served to enhance p-CAN production