Oxidative dehydrogenation of butane over nanocrystalline MgO, Al2O3, and VOx/MgO catalysts in the presence of small amounts of iodine

High surface area nanocrystalline MgO, Al2O3, MgO·Al2O3, commercial MgO, and a series of 10% V/MgO samples were used as catalysts in one-step selective oxidative dehydrogenation of butane to butadiene in the presence of oxygen and iodine. Molecular iodine shifts the equilibrium of the dehydrogenation reactions to the right and makes it possible to achieve high butane conversion with high selectivity to butadiene. When excess oxygen is present in the feed, iodine is successfully regenerated and can be recycled. Butadiene selectivity as high as 64% has been achieved in the presence of small amounts of iodine (0.25 vol%) over a vanadia–magnesia catalyst at 82% butane conversion. The best performance was observed over a catalyst containing the magnesium orthovanadate phase.