Oxidative Steam Reforming of Methane over Ni Catalysts Modified with Noble Metals

Abstract

The effects of addition of small amounts of noble metals such as Pt, Pd, and Rh to Ni/γ-Al₂O₃ and NiO-MgO solid solutions were investigated on the catalyst activation, catalyst bed temperature profile, and carbon formation behavior in oxidative steam reforming of methane. Addition of Pt and Pd by a sequential impregnation method to Ni/γ-Al₂O₃ had a much more remarkable effect than by a co-impregnation method on the resistance to deactivation by oxidation of Ni and suppression of hot-spot formation. Temperature-programmed reduction, extended X-ray absorption fine structure, and Fourier transform infrared spectroscopy suggested that the noble metal atoms introduced by the sequential impregnation method were preferably located on the surface to form an alloy. Addition of noble metals (Pt, Pd, and Rh) to Ni_0.2Mg_0.8O solid solution catalysts inhibited carbon formation in the oxidative steam reforming of methane under pressurized conditions.