A New Process for Maleic Anhydride Synthesis from a Renewable Building Block: The Gas-Phase Oxidehydration of Bio-1-butanol

We investigated the synthesisofmaleic anhydride by oxidehydration of abio-alcohol, 1-butanol,asapossible alternative to the classical process of n-butane oxidation. Avanadyl pyrophosphate catalystwas used to explore the one-pot reaction, which involved two sequential steps:1)1-butanol dehydration to 1-butene, catalysed by acid sites, and 2) the oxidation of butenes to maleic anhydride,catalysed by redox sites. Anon-negligible amount of phthalic anhydride wasalso formed. The effect of different experimentalparameters was investigated with chemically sourced1-butanol,and the results werethen confirmed by using genuinely bio-sourced 1-butanol. In the case of bio-1-butanol, however,the purity of the product remarkably affected the yield of maleic anhydride. It was found that the reactionmechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride.