A nitrogen-doped carbon modified nickel catalyst for the hydrogenation of levulinic acid under mild conditions

Abstract

The conversion of levulinic acid (LA) to γ-valerolactone (GVL) is one of the most important reactions from biomass-derived platform chemicals to value-added chemicals. In this work, nitrogen-doped carbon was introduced into a Ni/Al₂O₃ catalyst and was employed for the hydrogenation of LA to GVL with a full conversion and equivalent yield under mild conditions, at as low as ambient hydrogen pressure and 130 °C for 6 h. The doping of nitrogen introduced NiNx species and the imperfection of modified nitrogen-doped carbon were beneficial for the selective hydrogenation of carbonyl groups. This catalyst showed excellent activity and selectivity in various solvents and could be recycled for at least 6 runs with little deactivation. In addition to LA, various substrates with both carbonyl and carboxyl groups could also be selectively hydrogenated to the corresponding lactones. This study offers both theoretical foundation and practical instructions for the high-efficiency conversion of LA to GVL over non-noble metal catalysts under mild conditions, especially ambient H₂ pressure.