Selective Catalytic Oxidation of Methane to Syngas over Supported Mixed Oxides Containing Ni and Pt

The activity of Ni, Pt, and LaNiO3 supported on α-Al2O3 is studied in the selective catalytic oxidation of methane to syngas at 900°C and a contact time of ∼0.002 s using dilute mixtures (1000 ppm CH4 + 500 ppm O2 in He). The grain size was ∼100 μm. The method of X-ray phase analysis shows that supported LaNiO3, both pure and containing Pt, has a perovskite hexagonal structure with altered lattice parameters. Using temperature-programmed reduction by hydrogen, it was found that the reduction of supported LaNiO3 is simplified in the presence of Pt and/or Ce0.2Zr0.8O2. The activity and selectivity of the catalysts in the reaction of selective catalytic oxidation of methane depends on their composition and oxidative-reductive treatment. It was found that, in the presence of catalysts based on LaNiO3 and containing Pt and/or Ce0.2Zr0.8O2, the reaction occurs with an induction period. It was assumed that the value of the induction period depends both on the dynamics of phase LaNiO3 reduction to Ni, which is associated with the accumulation of carbonate complexes and surface hydroxylation, and on slow changes in the defect structure of Ce0.2Zr0.8O2, which are associated with oxidation-reduction.