Sustainable production of γ-valerolactone and δ-valerolactone through the coupling of hydrogenation and dehydrogenation

γ-Valerolactone (GVL) and δ-valerolactone (DVL) are valuable chemicals that can be obtained by catalytic processes from nonedible lignocellulose biomass. However, highly efficient synthesis of GVL and DVL through an environmentally friendly and cost-effective method is still a challenge. In this work, synchronized production of GVL and DVL with high yields (>98%) was realized over cheap Cu catalysts through catalytic coupling of 1,5-pentanediol (1,5-PDO) dehydrogenation and ethyl levulinate (EL) hydrogenation. Improved substrate conversion and selectivity to desired products can be observed in the combined reactions without the use of any solvent and consumption of hydrogen. In the coupled reactions, except using the hydrogen released from dehydrogenation, the large energy released from EL hydrogenation can be utilized effectively for endothermic 1,5-PDO dehydrogenation. In addition, easy temperature control in the combined reactions can be achieved due to moderate heat release, which can avoid the formation of apparent hotspots or coldspots in the practical process.