A Two-Step Process for Conversion of Cellulose to γ-Valerolactone over Raney Ni Catalyst Using H2O as a Hydrogen Source

Valorization of biomass to value-added platform compounds shows great potential to relieve the pressure on fossil energy consumption. Gamma (γ)-valerolactone (GVL) is a sustainable liquid for energy and carbon-based chemicals. Despite the numerous researches of investigation regarding the GVL synthesis from carbohydrate biomass, most of them involve the use of precious metals accompanying with the high-purity and high-pressure hydrogen, facing high cost in large-scale application and safety risk during the transportation and operation process. In this work, the cheap metal Fe was employed as a reductant for splitting water to produce hydrogen, and Raney Ni was used as a catalyst for in situ hydrogenation of obtained levulinic acid (LA) which is a key hydrolysate of cellulose to GVL. Cellulose was initially hydrolyzed to LA and then reduced to GVL without separation of other hydrolyzed intermediates of cellulose in one pot. The effect of reaction parameters on the yield of LA and GVL were studied for obtaining the optimal conditions. A 61.9 % yield of GVL from cellulose was achieved at mild hydrothermal conditions. This study provides an efficient approach for direct conversion of carbohydrate biomass to GVL with safe and abundant water as hydrogen source.