Isoprene and C5 Olefins Production by Oxidative Dehydrogenation of Isopentane

The current limited availability of isoprene and isoamylenes (methyl butenes), which are the feedstock for a variety of petrochemical processes, could be boosted by converting the isopentane contained in the same refinery C5-fractions from which they are obtained. The oxidative dehydrogenation (ODH) of isopentane to isoprene and isoamylenes for this purpose has been studied very little to date. We present here a study of this reaction on oxide catalysts, using oxygen as an oxidant, without any dopant in the feed. After a broad catalyst formulations screening, a V−Mg oxide catalyst (15 wt % V2O5) was selected to study the influence of the reaction parameters (temperature, residence time, and feed composition). Selectivity values of ca. 25% to isoprene, and 70% to isoprene plus isomylenes, could be attained under selected reaction conditions. These results are promising for the direct conversion of the branched C5-hydrocarbons fraction to isoprene.