Formation of perovskite-type LaNiO₃ on La-Ni/Al₂O₃-ZrO₂ catalysts and their performance for CO methanation

The carbon deposition and sintering of Ni-based catalysts, used in CO methanation, are the main problems to be solved. In this paper, supported LaNiO₃/Al₂O₃-ZrO₂ catalyst was prepared by neutralization hydrolysis-citric acid complexation method. The effects of La-Ni loading and calcination temperature of support on the structure and catalytic activity of the catalyst were investigated. The structural evolution of catalyst precursor before and after reduction was studied via XRD, H₂-TPR, BET, XPS, TEM and other characterization methods. The results showed that the catalyst supported by homogeneous Al-Zr solid solution was beneficial to form the active component with LaNiO₃ structure, and the Ni⁰ derived from LaNiO₃ was the key factor for keeping the activity at high temperature. The La-Ni loading affected the formation of LaNiO₃ and the reduction state of Ni. Among the catalysts studied, 30% of the La-Ni loading was more favorable for the formation of perovskite LaNiO₃. The Ni⁰ and La₂O₃ reduced from LaNiO₃ were highly dispersed on the surface of the support, and the Ni⁰ nanoparticles were anchored by the support and La₂O₃, which inhibited the migration and aggregation of Ni⁰ particles at high temperature and thus led to high thermal stability.