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Abstract

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoO_x systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO₂. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.