Conversion of levulinic acid to γ-valerolactone over Ru/Al₂O₃–TiO₂ catalyst under mild conditions

Abstract

Novel catalytic material with high catalytic activity and hydrothermal stability plays a key role in the efficient conversion of levulinic acid (LA) to γ-valerolactone (GVL) in water. In this study, mixed oxides Al₂O₃-TiO₂, Al₂O₃-MoO₃ and Al₂O₃-Co₃O₄ were synthesized by co-precipitation using aqueous solution of NaOH as precipitant. Ru catalysts supported on mixed oxides were prepared by impregnation method and their catalytic performances were tested in the hydrogenation of LA to GVL on a fixed bed reactor. The physicochemical properties of the catalysts were characterized by XRD, H₂-TPR, NH₃-TPD, and BET techniques. The TiO₂ component significantly affected the acidity of the catalyst, and thus its catalytic activity for the GVL yield was affected. The desired product GVL with a yield of about 97% was obtained over the Ru/Al₂O₃-TiO₂ catalyst under mild conditions (WHSV = 1.8 h^-1, <i>T</i> = 80 °C). Moreover, the catalyst Ru/Al₂O₃-TiO₂ exhibited excellent thermal stability in the test period of time.