Selective oxidative dehydrogenation of butane over VMgO catalysts

Vanadium-magnesium oxides were found to be selective oxidative dehydrogenation catalysts for butane. The selectivity for dehydrogenation increased with increasing vanadium content until an optimum was reached for samples containing 24 to 54 wt% V₂O₅. Infrared spectroscopy, X-ray diffraction, Auger electron spectroscopy, and scanning electron microscopy studies of the catalysts suggested that the active component was the compound magnesium orthovanadate. For a given catalyst at about 540 °C, the selectivity for oxidative dehydrogenation increased with decreasing oxygen-to-butane ratio, decreasing conversion, and decreasing temperature. A selectivity of up to 60% was obtained. The high selectivity for oxidative dehydrogenation instead of oxygenate production is attributed to two factors: the basic surface facilitates desorption of basic butenes and butadiene, and the absence of VO lowers the oxidation activity of the surface.