Partial oxidation of methane over a Ni/BaTiO3 catalyst prepared by solid phase crystallization

Abstract

Ni/BaTiO ₃ catalyst has been prepared by solid phase crystallization (SPC) and used successfully for partial oxidation of CH ₄ into synthesis gas at 800°C. In the SPC method, Ni/BaTiO ₃ catalyst is obtained in situ by the reaction of starting materials with nickel species homogeneously incorporated in the structure. For the starting reagents, materials of two compositional types were employed i.e., perovskite structures BaTi _1-x Ni _x O _{3- δ} (0⩽x⩽0.4) and stoichiometric structures, BaTiO ₃ , Ba ₂ TiO ₄ and BaTi ₅ O ₁₁ , with 0.3NiO. The starting materials were tested for oxidation of CH ₄ by increasing the reaction temperature from room temperature to 800°C. The catalysts showed the highest activity for synthesis gas formation around 800°C, and the highest value was obtained at a composition of x=0.3 in the former catalysts. Among the latter catalysts, the highest activity was observed over BaTiO ₃ ·0.3NiO, which was more active than BaTi _0.7 Ni _0.3 O _3-δ . On the both catalysts, nickel species originally incorporated in the structure were reduced to the metallic state during the reaction. The BaTiO ₃ ·0.3NiO catalyst was further tested for 75 hours at 800°C with no observable degradation and negligible coke formation on the catalyst. Thus, Ni/BaTiO ₃ prepared in situ from the perovskite precursor, i.e., by the SPC method, was the most active and resistant to coke formation and deactivation during the reaction. This may be due to well dispersed and stable Ni metal particles over the perovskite, where the nickel species thermally evolve from the cations homogeneously distributed inside an inert perovskite matrix as the precursor.