Mesoporous carbon and microporous zeolite supported Ru catalysts for selective levulinic acid hydrogenation into γ-valerolactone

Abstract Ru supported on mesoporous carbon Sibunit and microporous zeolites (HZSM-5, SiO2/Al2O3 = 250; H-Beta, SiO2/Al2O3 = 30; H-Y, SiO2/Al2O3 = 5; H-USY, SiO2/Al2O3 = 30) synthesized by the sol-gel method (CSIR-National Chemical Laboratory, Pune India) were prepared by impregnation of the corresponding supports with RuCl3∙nH2O (0.1 M) followed by reduction in H2. Catalyst screening in levulinic acid (LA) (15 mL, 6.9 mmol) hydrogenation into g-valerolactone (GVL) with 1,4-dioxane (165°C, hydrogen pressure ca. 16 bar) as a solvent showed higher activity and selectivity to GVL of Ru/zeolites compared to carbon supported catalysts. Among Ru/zeolites LA conversion increased as follows Ru/HZSM-5 < Ru/H-Y < Ru/H-USY < Ru/H-Beta demonstrating a clear advantage of H-Beta preparation method. Optimization of the support microstructure and acidity opens a reliable way for selective catalytic LA hydrogenation to GVL. The catalysts were analyzed by TEM, XRD, H2-TPR and N2 physisorption to compare their physical chemical properties.