Co-CxNy embedded in N-doped carbon as robust catalysts for the synthesis of γ-valerolactone from the hydrogenation of levulinic acid under low hydrogen pressure

Abstract

The rational design of non-noble metal catalysts for the highly efficient production of γ-valerolactone (GVL) from the selective hydrogenation of levulinic acid (LA) at mild reaction conditions is still a big challenge. In this work, the Co embedded in N-doped carbon as a robust catalyst is fabricated by in situ carbonizing ZIF-67 for the LA selective hydrogenation to GVL. Several catalysts that differed in pyrolysis temperatures, pyrolysis gas and preparation methods were prepared and evaluated. The optimal catalytic performance is achieved with Co@NC-800H, which realizes a up to 99% yield of GVL at low temperature of 120 °C and low hydrogen pressure of 0.5 MPa. Also, the optimal Co@NC-800H catalyst exhibits excellent reusability. By the careful characterizations with multiple techniques, including BET, XRD, SEM, TEM, XPS and Raman, it is found that the excellent catalytic performance of Co@NC-800H is achieved through the synergistic catalysis between oxygen vacancies and Co-CxNy sites.