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 N-2 adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM)/high-resolution TEM, H-2-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 degrees C under atmospheric pressure at weight hourly space velocity (WHSV) of 60,000 h(-)(1).g(cat)(-1) and a reactant molar ratio of CO2/H-2/Ar = 15/60/25. Steady-state tests were carried out at 300 degrees 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.