Selective hydrogenation of levulinic acid to γ-valerolactone using bimetallic Pd-Fe catalyst supported on titanium oxide

Abstract

The synthesis of γ-valerolactone (GVL), a versatile precursor in the manufacture of high-value chemicals such as polymer plasticizer, solvent, jet fuel, and, agrochemicals, has been targeted by many research groups. In this study, we report the catalytic performance of iron-modified palladium supported on titanium oxide (denoted as Pd(5.0)-Fe(5.0)/TiO2; 5.0 was the loading amount of Pd and Fe, respectively) in the selective hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) in stainless-steel batch reactor system. Pd(5.0)-Fe(5.0)/TiO2 catalyst was synthesized by a simple hydrothermal method at 150°C for 24 h, then followed by reduction with H2 at 500°C for 3 h. The X-ray diffraction (XRD) patterns of Pd(5.0)-Fe(5.0)/TiO2 before and after reduction showed the formation of metallic Pd at 2θ = 40.34° and 47.2° corresponding to Pd(111) and Pd(200), respectively. The hydrogenation of LA to GVL effectively occurred in the H2O solvent, whereas in 2-propanol the formation of ester was the main side product. The highest yield of GVL (52.5%) was obtained over Pd(5.0)-Fe(5.0)/TiO2 catalyst at a temperature of 170 °C, initial H2 pressure of 4.0 MPa, solvent H2O 3 ml at a reaction time of 7 h. The yield of GVL slightly increased to 63.3% when the reaction time was prolonged to 15 h.