Effect of lanthanum on catalytic performance of Ru/Al2O3 catalyst for hydrogenation of esters to corresponding alcohols

Ru-La/γ-Al2O3 catalyst was prepared by impregnation method and characterized by temperature programmed reduction(TPR), transmission electron microscopy(TEM), X-ray photoelectron spectra(XPS), Brunauer-Emmett-Teller(BET), X-ray diffraction(XRD), and NH3-temperature programmed desorption(NH3-TPD). NH3-TPD revealed that the strong acidic centers in γ-Al2O3 are not the major factor to cause the hydrolysis of esters to acids in the hydrogenation of esters. The results of TPR and TEM indicate that the appropriately added lanthanum results in the good dispersion of ruthenium and the easy reduction of ruthenium oxide on Ru-La/γ-Al2O3, which could promote the catalytic activity of Ru-La/γ-Al2O3 for the hydrogenation of methyl propionate to propanol. When the amount of lanthanum added in the catalyst was up to 9%(mass fraction), 4%Ru-9%La/γ-Al2O3 catalyst gave a conversion of methyl propionate of 98.1% and a selectivity of 94.8% to propanol at a reaction temperature of 180 °C and a hydrogen pressure of 5.0 MPa.