High activity and stability of nano‐nickel catalyst based on LaNiO3 perovskite for methane bireforming

Abstract

AbstractIn this study, a nano‐nickel Ni0 catalyst for bireforming of methane was in‐situ synthesized from the sol‐gel fabricating LaNiO3 perovskite. The various physico‐chemical methods such as powder X‐ray diffraction (XRD), energy‐dispersive X‐ray spectroscopy (EDS), H2 temperature‐programmed reduction (H2‐TPR), scanning electron microscopy (SEM), and CO2 temperature‐programmed desorption (CO2‐TPD) were used for characterization of the obtained samples. The coke accumulation was investigated via the temperature‐programmed oxidation (TPO) method. The results confirmed the formation of both LaNiO3 perovskite structure and a small amount of NiO with high crystallinity. H2‐TPR profiles and XRD patterns showed that the highly dispersed nanocrystals Ni0 on La2O3 catalysts were formed by in‐situ reduction of LaNiO3 at 800°C for as short as 1 hour or more. The crystal sizes of Ni0 and La2O3 crystals are in the range of 17‐18 nm and 18‐19 nm, respectively. The activity of the catalysts was studied in bireforming of methane by the micro‐flow method in a temperature range of 550‐800°C. LaNiO3‐based catalyst showed excellent performance for methane bireforming reaction. Of which, LaNiO3 sample calcined at 800°C for 1.5 hours and reduced at 800°C for 1.5 hours showed the highest activity when it reached the CH4 conversion of 87% and abnormally high CO2 conversion, reaching 97 % at 700°C and approximately 100 % at 800°C with an ideal H2/CO ratio of approximately 2. At 800°C, the activity of the most outstanding catalyst remained stable for 100 hrs thanks to the high sintering resistance of excellent dispersion of Ni in LaNiO3 lattice and high coke tolerance of the catalyst. The catalytic activity remained stable even when the amount of inert γ‐carbon reached 8.58 mgC/gcat.