Mechanistic Insights on the Formation of Maleic Anhydride from the Oxidation of Levulinic Acid over Supported Vanadates

With the realization that, even though biomass derived transportation fuels present a great solution to the diminishing oil reserves, they cannot compete with their petrochemical equivalents, we turn our attention to bio-based commodity chemicals. Those have the potential to compete with the existing market and present opportunities for the utilization of lignocellulosic biomass. Along those lines, we present an alternative catalytic pathway for the production of maleic anhydride (MA) through the gas phase oxidative cleavage of the methyl carbon in levulinic acid (LA). We previously showed that over a vanadia phase supported on silica, high yields of MA (71%) can be achieved. We were also intrigued to observe that the methyl carbon cleavage does not occur on monofunctional methyl ketones. Here, we try to probe the nature of this unique chemistry, by employing a number of different ketones and keto-carboxylic acids in order to decide if this unique selectivity is due to steric effects or the dual functionality of LA.