Mild production of -valerolactone, a biofuel precursor, through the catalytic hydrogenation of a biomass derivative using hydrogen produced by photoelectrochemical water splitting

In this article, an efficient and innovative coupled system that involves hydrogen generation from water and hydrogenation of a biomass derived compound is shown for the first time. We have demonstrated that it is possible to use hydrogen produced from photoelectrochemical water splitting for the hydrogenation of a widely available biomass-derived compound (levulinic acid) into a versatile fuel component and/or precursor (gamma-valerolactone). This compound, conversely to hydrogen, can be easily stored and handled. The photoelectrocatalyst selected was a TiO2 nanostructure synthesized by electrochemical anodization. The hydrogen produced was simultaneously used to carry out a hydrogenation reaction to transform levulinic acid into gamma-valerolactone. The generated hydrogen was transferred to a catalytic reactor containing an aqueous solution of levulinic acid (LA) in the presence of a Ru based catalyst. Remarkable formation of gamma-valerolactone (GVL) was obtained at temperatures as low as 30-60 C-degrees. Yields to GVL of ca. 95 % have been obtained with this novel coupled system at only 60 C-degrees. These results confirm the potential utilization in the biomass valorization of in-situ hydrogen production by photoelectrochemical water splitting.