Effect of Preparation Methods on the Physicochemical and Functional Properties of Ni/CeO2 Catalysts

Abstract

The effect of preparation procedures (a polymer ester precursor method and incipient wetness impregnation) on the physicochemical and functional properties of Ni/CeO2 catalysts with different nickel contents (0–15 wt %) was studied in order to develop highly active and carbonization-resistant catalysts for hydrocarbon reforming. Based on the results of studying the samples by low-temperature nitrogen adsorption, X-ray phase analysis, Raman spectroscopy, transmission electron microscopy and temperature-programmed reduction with hydrogen, it was found that the textural, structural, and redox properties of the materials depend on the method of their synthesis. As compared with the samples prepared by impregnation, the Ni/CeO2 catalysts obtained by the polymer ester precursor method were characterized by different active component stabilization forms (a Ce1 –xNixOy solid solution phase and NiO particles <5 nm in size vs. a NiO phase with a particle size of 5–50 nm), a smaller average size of CeO2 crystallites (5.5 vs. 11 nm), a high specific surface area (105 vs. 75 m2/g), a defect structure, and a decreased reducibility. It was found that the samples of both series provided comparable yields of hydrogen (to 50% at 600°C) in an autothermal ethanol reforming reaction, but the Ni/CeO2 catalysts synthesized by the polymer ester precursor method were more resistant to the formation of carbonaceous deposits.