Catalytic Transfer Hydrogenation of Levulinic Acid to γ-Valerolactone over Ni3P-CePO4 Catalysts

A series of Ni3P-CePO4(x) catalysts were prepared by H2 temperature-programmed reduction and utilized to catalyze the transfer hydrogenation (CTH) of levulinic acid (LA) to γ-valerolactone (GVL). The characterization of the synthesized catalysts was carried out by means of XRD, N2-adsorption/desorption, NH3-TPD, CO2-TPD, TEM, EDS elemental mapping, ICP, XPS, and TG/DSC. The effects of Ce/Ni molar ratio, reaction temperature, reaction time, and hydrogen donor on the CTH performance were studied. The yield of GVL was 89.9% at an LA conversion of 99.9% at 180 °C for 2 h over the Ni3P-CePO4(0.1) catalyst using 2-propanol as the solvent. The NH3-TPD and CO2-TPD measurements and poisoning experiments verified that acidic/basic sites played a synergic role in the process. A slight decrease in LA conversion and GVL yield was observed after four consecutive cycles. The characterization of the fresh and spent catalysts indicated that the minor deactivation was due to the deposition of insoluble organics or polymers rather than the changes of the crystal phase or acidic/basic properties, or the leaching of the active sites.