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Cerium-based bimetallic oxides of the type 3NiO·CeO2, Co3O4·CeO2, and 1.5Fe2O3·CeO2 were prepared by two sol–gel methods (epoxide addition and Pechini methods) and by the electrospinning technique, aiming at the synthesis of compounds with different morphologies (nanoparticles or nanofibers) and the evaluation as catalysts for the methanation of CO2. The results obtained show a catalytic performance that depends on the type of d block element, method, and catalyst morphology. Regardless of such parameters, the best results were those obtained over the nickel-based catalysts prepared by the electrospinning technique that are remarkably more active than a commercial rhodium catalyst used as a reference and tested in the same conditions. Moreover, the cobalt-based catalysts obtained either as nanoparticles (Pechini method) or fibers (electrospinning technique) present also a good activity, comparable to that measured over the reference catalyst. All catalysts were very stable to deactivation during at least 60–70 h of reaction, which is clearly an advantage that could make them an alternative to be considered for future developments in this area of knowledge.

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Cobalt-lanthanide bimetallic oxide nanofibers (5Co 3 O 4 .3LnCoO 3 , Ln=La, Pr; 4Co 3 O 4 .Ln 2 O 3 , Ln=Sm, Gd, Dy, Yb and 2Co 3 O 4 .CeO 2 ) were prepared by electrospinning technique and for the first time evaluated as catalysts for the hydrogenation of CO 2 . Depending on the lanthanide, the reaction products are different: lighter lanthanides (La, Pr, Sm and Gd) produce mainly CO and are more active to reverse water gas shift (RWGS), whereas the catalysts with Ce, Dy and Yb are more active and selective to methane. Lanthanide intrinsic properties such as ionic radii and basicity strongly correlate with the nanofibers' catalytic performance: lower lanthanide ionic radii and higher basicity favour the catalysts activity. Moreover, the bimetallic oxide nanofibers catalytic behavior also seems to point to the existence of a synergetic interaction between cobalt and lanthanide. The cobalt-lanthanide bimetallic oxides present a high deactivation resistance for at least 60 h in the gaseous stream, which is an advantage for any catalytic application. Compared with a commercial catalyst (5 wt.% Rh/Al 2 O 3 ) tested in the same conditions, cobalt-ytterbium, dysprosium and cerium bimetallic oxide nanofibers present an activity 5 to 13 times higher at 350 °C.