Physico-chemical properties and catalytic activity of the sol-gel prepared Ce-ion doped LaMnO3 perovskites

Ce-doped LaMnO3 perovskite ceramics (La1−xCexMnO3) were synthesized by sol-gel based co-precipitation method and tested for the oxidation of benzyl alcohol using molecular oxygen. Benzyl alcohol conversion of ca. 25–42% was achieved with benzaldehyde as the main product. X-ray diffraction (XRD), thermogravimetric analysis (TGA), BET surface area, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (H2-TPR), temperature-programmed oxidation (O2-TPO), FT-IR and UV-vis spectroscopic techniques were used to examine the physiochemical properties. XRD analysis demonstrates the single phase crystalline high purity of the perovskite. The Ce-doped LaMnO3 perovskite demonstrated reducibility at low-temperature and higher mobility of surface O2-ion than their respective un-doped perovskite. The substitution of Ce3+ ion into the perovskite matrix improve the surface redox properties, which strongly influenced the catalytic activity of the material. The LaMnO3 perovskite exhibited considerable activity to benzyl alcohol oxidation but suffered a slow deactivation with time-on-stream. Nevertheless, the insertion of the A site metal cation with a trivalent Ce3+ metal cation led to an enhanced in catalytic performance because of atomic-scale interactions between the A and B active site. La0.95Ce0.05MnO3 catalyst demonstrated the excellent catalytic activity with a selectivity of 99% at 120 °C.