Behavior of supported, and molybdenum and gallium promoted, V-Mg-O catalysts in the oxidative dehydrogenation of n-butane

Perhaps one of the most promising catalysts found for the n-butane oxidative dehydrogenation is a mixture of vanadium and magnesium oxides with an atomic Mg/V ratio of 4. A study was carried out to solve some of the drawbacks of this catalyst by the addition of different amounts of promoters. Catalysts tests were performed in an isothermal packed bed tubular quartz reactor operated at 1 atm, 480°-540°C, and 6-50 gcat/(moltot/min). All catalysts showed dependence with the reaction temperature and the contact time within the expected trends, and a reduced activity when they were compared to the basic catalyst (V-Mg-O). Selectivity toward dehydrogenated hydrocarbons increased with increasing contents of molybdenum; opposed variation was observed when the promoter was the gallium oxide. Molybdenum enhanced the selectivity toward butenes over the selectivity toward butadiene. The catalyst prepared supporting the V-Mg-O phase over the attrition resistant SiO ₂ showed comparable levels on selectivity when compared with the non-supported one, but with a reduced activity. This is an abstract of a paper presented at the 7th World Congress of Chemical Engineering (Glasgow, Scotland 7/10-14/2005).