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

Abstract

Abstract In this study, a nano‐nickel Ni 0 catalyst for bireforming of methane was in‐situ synthesized from the sol‐gel fabricating LaNiO 3 perovskite. The various physico‐chemical methods such as powder X‐ray diffraction (XRD), energy‐dispersive X‐ray spectroscopy (EDS), H 2 temperature‐programmed reduction (H 2 ‐TPR), scanning electron microscopy (SEM), and CO 2 temperature‐programmed desorption (CO 2 ‐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 LaNiO 3 perovskite structure and a small amount of NiO with high crystallinity. H 2 ‐TPR profiles and XRD patterns showed that the highly dispersed nanocrystals Ni 0 on La 2 O 3 catalysts were formed by in‐situ reduction of LaNiO 3 at 800°C for as short as 1 hour or more. The crystal sizes of Ni 0 and La 2 O 3 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. LaNiO 3 ‐based catalyst showed excellent performance for methane bireforming reaction. Of which, LaNiO 3 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 CH 4 conversion of 87% and abnormally high CO 2 conversion, reaching 97 % at 700°C and approximately 100 % at 800°C with an ideal H 2 /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 LaNiO 3 lattice and high coke tolerance of the catalyst. The catalytic activity remained stable even when the amount of inert γ‐carbon reached 8.58 mg C /g cat .

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