Oxidative reforming of model biogas over NiOaY2O3aZrO2 catalysts

Catalysts composed of NiO/Y2O3/ZrO2 mixtures were synthesized by the polymerization method in a single step. They were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), physisorption of N2 (BET) and X-ray photoelectron spectroscopy (XPS) and then tested in the oxidative reforming of a model biogas (1.5CH4: 1CO2) in the presence of oxygen (1.5CH4 + 1CO2 + 0.25O2) at 750 degree C for 6 h. It was observed that the catalysts Ni20YZ and Ni40YZ performed better in catalytic processes than NiO/ZrO2 and NiO/Y2O3, synthesized under the same conditions. The formation of Y2O3aZrO2 and NiOaY2O3 solid solutions increased the rates of conversion of the reactants (CH4 and CO2) into synthesis gas (H2 + CO). The formation of oxygen vacancies (in samples containing ZrO2 and Y2O3) seemed to promote removal of the coke deposited on the nickel surface during the oxidative reforming of model biogas. The H2/CO ratios in the reaction products formed on the best catalysts were 1: 1, which is desirable for their direct use in the STD and in the FischeraTropsch processes.