Direct biomass valorisation to γ-valerolactone by Ru-PNP catalysed hydrogenation in acid†

Abstract

Converting carbohydrate-rich biomass waste directly to γ-valerolactone (GVL) is highly attractive but challenging owing to the inert nature and high complexity of biomass, necessitating a versatile and selective catalytic system. Herein, we describe the first direct conversion of monosaccharides (glucose, fructose, and xylose) and polysaccharides (cellulose and hemicellulose) in high yields under mild conditions. We also present the first direct conversion of raw lignocellulose, starch, and chitin biomass to GVL. Using the homogeneous catalyst Ru-MACHO-BH in H₃PO₄(aq) under 30 bar H₂ at 125–140 °C for 24–120 hours provides GVL in excellent yields (26–48 mol%).