Oxidative dehydrogenation (ODH) of propane offers an attractive alternative to the traditional methods for industrial production of propylene. It does not lead to the formation of coke. Vanadium is an attractive candidate for ODH catalysis due to its rich redox chemistry with several oxidation states (+2, +3, +4, +5) and variable coordination geometries (tetrahedral, square pyramidal and octahedral). Herein, we describe the catalytic activity of a novel highly reduced polyoxovanadate cluster, (NH4)8[V(IV)12V(V)6O42(XO4)]�10H2O (X = V,S) (NH4V18) for the ODH of propane.Materials and MethodsFine powders of unsupported catalyst were prepared directly from crystals. Supported catalysts were prepared by loading NH4V18 on ?-alumina through incipient wetness method. A quartz reactor connected to a GC was used for catalytic studies in temperature range of 300-600 �C. Single Crystal X-ray diffraction, Elemental Analysis, Thermogravimetric Analysis (TGA), BET Surface Area Analysis and Temperature Programmed Reduction (H2-TPR) were used for the characterization of the catalysts.Results and DiscussionFigure 1 shows the crystal structure of NH4V18 , composed of 18 edge-sharing {VO5} square pyramids. The giant oxovanadate cage encapsulates a XO4 unit (X =V, S). NH4+ cations balance the charge. Unsupported NH4V18 has 60% propylene selectivity (at 1% propane conversion) at a relatively low temperature, 350 �C. ?-alumina supported NH4V18 reaches a very high conversion level of 20% with 41% propylene selectivity at the temperature of 450�C. Conversion levels keep increasing as temperature increases gradually to 600 �C. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/239nm/uploads/12081_figure_1_acs.jpg' alt='' />

Novel reduced polyoxovanadate cluster as oxidative dehydrogenation catalyst for propane

246th National Meeting (2013)

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