Structural Reversibility and Nickel Particle stability in Lanthanum Iron Nickel Perovskite-Type Catalysts
Perovskite-type oxides have shown the ability to reversibly segregate precious metals from their structure. This reversible segregation behavior was explored for a commonly used catalyst metal, Ni, to prevent Ni sintering, which is observed on most catalyst support materials. Temperature-programmed reduction, X-ray diffraction, X-ray absorption spectroscopy, electron microscopy, and catalytic activity tests were used to follow the extent of reversible Ni segregation. LaFe1-xNixO3-delta (0 <= x <= 0.2) was synthesized using a citrate-based solution pro-cess. After reduction at 600 degrees C, metallic Ni particles were displayed on the perovskite surfaces, which were active towards the hydrogenation of CO2. The overall Ni reducibility was proportional to the Ni content and increased from 35% for x=0.05 to 50% for x=0.2. Furthermore, Ni could be reincorporated reversibly into the perovskite lattice during reoxidation at 650 degrees C. This could be exploited for catalyst regeneration under conditions under which impregnated materials such as Ni/ LaFeO3-delta and Ni/Al2O3 suffer from sintering.
Steiger, P., Delmelle, R., Foppiano, D., Holzer, L., Heel, A., Nachtegaal, M., . . . Ferri, D. (2017). Structural Reversibility and Nickel Particle stability in Lanthanum Iron Nickel Perovskite-Type Catalysts. Chemsuschem, 10(11), 2505-2517. doi:10.1002/cssc.201700358