Ni-enacapulated carbon catalyst with enhanced catalytic stability for hydrogenation of levulinic acid to γ-valerolactone

In this study, we demonstrate that applying a nitrogen-doped carbon coating to nickel (Ni@NC) improves its durability for converting levulinic acid (LA) into γ-valerolactone (GVL) through hydrogenation. Various characterization techniques revealed that the carbon structure is porous, with nickel being highly dispersed and embedded due to a strong interaction between the nickel and carbon framework. Catalytic tests for LA hydrogenation were conducted at temperatures ranging from 200 to 260 °C under atmospheric pressure, with different weight hourly space velocity (WHSV) values. The Ni@NC catalyst was found to be optimal, achieving 88% conversion of LA and 100% selectivity for GVL at 240 °C with a WHSV of 1.14 h^-1. This catalyst maintained a high GVL yield and excellent long-term stability for 100 hours under conditions of WHSV of 2.28 h^-1 at 260 °C and atmospheric pressure. In contrast, the Ni/g-C₃N₄ catalyst, prepared using the impregnation method, produced a good GVL yield but exhibited poor stability under the same conditions. These findings suggest that catalysts with strong metal-support interactions can potentially improve stability.