Ni/CeO₂ Nanoparticles Promoted by Yttrium Doping as Catalysts for CO₂ Methanation

Ni (5 wt %) catalysts over yttrium-modified CeO2 oxides synthesized by the hydrothermal method were prepared. For comparison, Ni was supported over pure CeO2 and Y2O3. Characterizations by N2 adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM)/high-resolution TEM, H2-temperature-programmed reduction, CO2-temperature-programmed desorption, and thermogravimetric analyses were carried out. The catalytic performance in CO2 methanation reaction was tested between 200 and 450 °C under atmospheric pressure at weight hourly space velocity (WHSV) of 60,000 h–1·gcat–1 and a reactant molar ratio of CO2/H2/Ar = 15/60/25. Steady-state tests were carried out at 300 °C for 7 h over selected catalysts. Doping CeO2 with Y promotes the decrease of the particle size of CeO2 and the formation of CeO2 nanorods, increases the specific surface area and the number of oxygen vacancies, and enhances the metal–support interaction with respect to unpromoted Ni/CeO2. The methanation results showed that the 2 wt % Y-modified Ni/CeO2 catalyst exhibited the best CO2 conversion and high selectivity toward methane.