Dual Active-Site Mechanism for Dry Methane Reforming over Ni/La ₂ O ₃ Produced from LaNiO ₃ Perovskite

The kinetic behavior of the Ni/La 2 O 3 catalyst obtained from the LaNiO 3 perovskite in the reforming reaction of methane with carbon dioxide was investigated as function of temperature and CH 4 and CO 2 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 La 2 O 3 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 La 2 O 2 CO 3 species which are formed by interaction of La 2 O 3 with CO 2 . Catalytic activity occurs at the Ni−La 2 O 2 CO 3 interface, while the oxycarbonate species participate directly by reacting with deposited carbon, thus restoring the activity of the Ni sites at the interface.