Direct Conversion of Glycerol to Allyl Alcohol Over Alumina-Supported Rhenium Oxide

The deoxydehydration (DODH) of glycerol was studied using several Re-based catalysts in the liquid phase under atmospheric pressure conditions. The best performance was observed over 10 wt.% ReOx/Al2O3 with 2-hexanol as a reductive agent giving allyl alcohol with an exceptional yield of 91%. The reaction was confirmed to be catalysed heterogeneously, since the reaction stopped upon removal of the catalyst by hot filtration. The corresponding catalyst was further successfully reused three times without any leaching of rhenium species, as shown by elemental analysis. Based on the characterisation of the fresh and the spent catalyst by XPS and Raman spectroscopy, a reaction mechanism is proposed, which involves the redox-couple Re(V) / Re(VII).