Oxidation of 3- and 4-Methylpyridines on Vanadium-Anatase and Vanadium-Rutile Catalysts

Abstract

<p>Heterogeneous catalytic vapor-phase oxidation of methylpyridines is “green”, the most simple and perspective method for obtaining pyridinecarboxylic acids. Vanadium-titanium catalysts have a wide application in some important industrial processes of oxidation. Oxidation of 3-and 4-methylpyridine on vanadium-titanium catalysts has been investigated and for its preparation various titanium crystal modifications were used. Characterization of the catalysts was carried out by using the X-ray diffraction, N₂-adsorbtion and thermal dissociation of V₂O₅. It was found that the use of anatase type of TiO₂ with a higher BET surface area enhances the activity of the vanadium-titanium catalyst extremely. XRD-characterization of catalysts demonstrated that the only V₂O₅ and anatase or V₂O₅ and rutile phase was detected. It was established that the use of titanium dioxide of crystal modifications of anatase increases on the order of the dissociation rate V₂O₅. It was shown that vanadium-titanium catalysts’ activity and selectivity in investigated processes depends on TiO₂ crystal modifications.V₂O₅-anatase is more active and selective in formation of pyridine carboxylic acids. V₂O₅-rutile in the process of oxidation of 4-methylpyridine on the catalyst forms the mixture of isonicotinic acid and its aldehyde. Connection between the dissociation rate of V₂O₅ in catalysts of V₂O₅-anatase and V₂O₅-rutile and their activity in isomeric methylpyridines oxidation was established. High surface area, anatase structure of titanium are the key parameters determining the activity and selectivity of vanadium-titanium oxidation catalysts.</p>