Pulse study of CO₂ reforming of methane over LaNiO₃

The perovskite type oxide LaNiO₃ was used as starting material for the CO₂ reforming of methane. The reaction was studied by a pulse technique using a CH₄/CO₂ ratio close to one, in order to understand the catalyst behavior. LaNiO₃ was reduced prior to the reaction by temperature programmed reduction (TPR) under hydrogen. The catalyst was thus composed of La₂O₃ and Ni⁰. We have shown that good catalytic performances were obtained at 700°C and 800°C. At 800°C all the CH₄ was transformed whereas the CO₂ conversion reached 92% with a H₂/CO ratio equal to 0.91. The crystallographic phases present after catalyst stabilization by the reaction depends on the reaction temperature. At 800°C the only phases present are La₂O₃ and metallic nickel whereas at 700°C the spinel phase La₂NiO₄ was identified leading to the conclusion that the CO₂ reforming of CH₄ involve consecutive reactions occurring simultaneously in our experimental conditions: Ni⁰+La₂O₃+CO₂↔CO+La₂ NiO₄andCH₄+La₂NiO₄→CO+2H₂ +La₂O₃+Ni⁰.