Effect of ceria morphology on the carbon deposition during steam reforming of ethanol over Ni/CeO2 catalysts

Abstract

Ceria nanostructures (particles, rods and cubes) were used as support of 10 wt. % Ni/CeO2 catalysts and tested in the steam reforming of ethanol (SRE) reaction at stoichiometric conditions. Supports were prepared by precipitation and hydrothermal methods. Nickel was incorporated by incipient wetness impregnation. Catalysts were characterized by N2 adsorption, EDS, X-ray diffraction, transmission electron microscopy, Raman spectroscopy, N2O chemisorption, temperature programed reduction and CO-oxidation. Characterization of materials showed differences in the nickel particle size, nickel dispersion and its interaction with the ceria support, all these features dependent on the morphology of ceria; trends observed in calcined samples are retrieved in the reduced catalysts. Nickel supported on ceria rods (Ni/Ce-r) exhibited the best activity and hydrogen yield in the SRE reaction at 550 °C for 24 h under stream. Moreover, temperature-programmed oxidation of spent catalysts showed that the Ni/Ce-r sample presented the lower amount of carbon deposits which were also removed at lower temperatures. These characteristics of the rod-shaped catalyst were ascribed to the enhanced oxygen storage capacity presented by ceria rods and the higher dispersion of nickel over this ceria nanostructure.