Dual Active-Site Mechanism for Dry Methane Reforming over Ni/La2O3Produced from LaNiO3Perovskite

The kinetic behavior of the Ni/La2O3 catalyst obtained from the LaNiO3 perovskite in the reforming reaction of methane with carbon dioxide was investigated as function of temperature and CH4 and CO2 partial pressure. A rate reaction equation was developed including for the first time the presence of two active sites in this type of catalyst: the metallic nickel particles and the La2O3 which is the metal support. This kinetic model fits very well the experimental data, and the rate expression predicts better the rate of methane conversion than the models which incorporate only the metallic cluster as the active sites. X-ray photoelectron spectroscopy (XPS) of the catalyst after reaction suggests that Ni particles are partially covered by La2O2CO3 species which are formed by interaction of La2O3 with CO2. Catalytic activity occurs at the Ni−La2O2CO3 interface, while the oxycarbonate species participate directly by reacting with deposited carbon, thus restoring the activity of the Ni sites at the interface.