Partial Oxidation of Isobutane and Isobutene to Methacrolein Over a Novel Mo–V–Nb(–Te) Mixed Oxide Catalyst

Abstract

Aiming at a catalyst with improved catalytic properties in the oxidation of isobutane and isobutene to methacrolein and methacrylic acid, a novel MoVNb(Te) mixed oxide catalyst was synthesized. Rietveld analysis revealed that the crystal structure is well distinguishable from the known MoVTeNb mixed oxide catalyst used in the (amm-)oxidation of C3 hydrocarbons. In the conversion of isobutane, activity as well as selectivities to methacrolein and methacrylic acid were low, and the dehydrogenation of isobutane to isobutene was found to be rate determining. However, the novel catalyst is highly suitable for the partial oxidation of isobutene. While selectivity to methacrolein is comparable to that reported for other catalysts, the activity is superior, resulting in very high space-time-yields at temperatures up to 420 °C. The novel mixed oxide is a Mars van Krevelen-type catalyst. Excess oxygen in the feed is required to ensure optimum performance.