A sustainable process for the production of γ-valerolactone by hydrogenation of biomass-derived levulinic acid

A sustainable process for the hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) is reported. GVL can be easily obtained in high yield, adopting very mild reaction conditions, by the hydrogenation of an aqueous solution of levulinic acid using a commercial ruthenium supported catalyst in combination with a heterogeneous acid co-catalyst, such as the ion exchange resins Amberlyst A70 or A15, niobium phosphate, or oxide. All the hydrogenations were carried out at 70-50 degrees C and at low hydrogen pressure (3-0.5 MPa). The most effective acid co-catalyst was the ion exchange resin Amberlyst A70, which produced a high yield of GVL (99 mol%) and an activity of 558 h(-1) after 3 h of reaction, whilst working at 0.5 MPa of hydrogen and 70 degrees C. The combined effect of acid and hydrogenating heterogeneous components was also verified for the hydrogenation of aliphatic ketones to the corresponding alcohols, thus opening a new perspective for this process.