NiCo and NiCu Based-Materials for Hydrogen Production and Electro-oxidation Reactions
Pp. 129-161 (33)
Moises R. Cesario, Daniel A. Macedo, Glageane S. Souza, Francisco J.A. Loureiro, Haingomalala L. Tidahy, Cedric Gennequin and Edmond Abi- Aad
Ni1-xCoxO-CGO, Ni1-xCuxO-CGO, CuOCGO and NiO-CGO composites
powders were obtained by a one-step synthesis method and their catalytic activities in
dry reforming of methane (CH4+CO2) for hydrogen production were evaluated. X-ray
diffraction (XRD) analysis of composite powders confirmed NiO, Co3O4, CuO and
Ce0.9Gd0.1O1.95 cubic phases. XRD results also showed the formation of nanocrystalline
materials. Cobalt-based materials showed higher surface area values (SBET) than
copper-based materials. According to temperature programmed reduction (TPR)
analyses, Ni0.6Co0.4O-CGO (NiCo0.4) and Ni0.4Co0.6O-CGO (NiCo0.6) catalysts have
higher reduction capacity and stronger metal/support interaction than Ni0.6Cu0.4O-CGO
(NiCu0.4) and Ni0.4Cu0.6O-CGO (NiCu0.6) materials. Rietveld refinement analyses for
NiCo0.4, NiCo0.6 and NiCu0.4 reduced catalysts, confirmed the presence of Ni-Co and Ni-
Cu alloys. These factors are important for enhanced catalytic activity avoiding carbon
deposition. NiCo0.4 and NiCo0.6 catalysts had higher conversions of CH4 and CO2 than
Ni-CGO and Cu-based catalysts. NiCo-based catalyst showed a better resistance to
carbon deposition. NiCo0.4 had high H2/CO ratio and the best reaction selectivity below
600 ºC. The electrocatalytic activity of NiCo0.4/CGO/NiCo0.4 screen-printed
symmetrical cells from hydrogen and synthetic biogas (CH4+CO2) electro-oxidation
reaction was studied by impedance spectroscopy in the temperature range between 650
and 850 ºC. The polarization resistance was influenced by the atmosphere conditions.
Total polarization resistances (Rp) of 0.96 and 36.10 Ω cm2 were obtained at 750 °C for H2 and biogas atmospheres, respectively. The activation energy (Ea) was lower when H2
was used (0.92 eV). The hydrogen oxidation reaction occurs more easily than the dry
reforming of methane.
Alloy, Carbon Deposition, Dry Reforming of Methane, One Step
Synthesis, Electro-Oxidation Reaction, Hydrogen, Impedance Spectroscopy
Surface Area, Metal/Support Interaction, Reduction Capacity.
Unite de Chimie Environnementale et Interactions sur le Vivant (UCEIV, E.A. 4492), MREI, Universite du Littoral Cote d'Ople (ULCO), 59140, Dunkerque, France.