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

Abstract

In 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.

Furfural Hydrogenation Over Reduced Pure (LaBO3) and Substituted (LaB0.5B'0.5O3) (B, B': Fe, Co, Ni) Perovskites

“…In contrast, in Figure 4, it is seen for calcined LaNiO 3 perovskite a high desorption peak centered at 850 °C. After reduction process, the strong basic site was modified, observing a shifted to lower desorption temperature at 658 °C attributed to carbonate species, [54] in agree with XRD result. The new desorption peak at 345 °C can be attributed to moderately basic sites, in agreement with Das et al.…”

Chitosan-Mediated Coupling of MgFe2O4–TiO2 Nanocomposites for Efficient Methylene Blue Photodegradation

“…Therefore, applying the suitable calcination duration ensures the good catalytic efficiency of the material as well as proposes an economical aspect in timing and energy usage, eventually reducing costs and expanding the practical application in phototreatment on a mass scale. 48 The aforementioned findings are supported by the composition and size alternations of the oxide nanoparticles formed in the SEM images and EDS spectra. As can be observed, increasing the exposure duration at a high temperature is mainly responsible for the decomposition of chitosan carriers through significant changes in the elemental C and O composition, as well as the dehydration from metallic hydroxide to oxide via the conveyance of the base oxide to each other to form the ferrite and its coupling with TiO 2 .…”

“…Specifically, based on the results in Table S2, upon the efficient calcination treatment at 800 °C, the rate constants of MFO-TiO 2 samples were considerably promoted as compared to the lowest value (0.0393 min –1 ) of the one prepared at 80 °C for 6 h. Along with the acquired good structural and topological characteristics, 2 h is further validated to be the appropriate calcination time for not only the ferrite preparation but also the photocatalytic potential with the highest rate constant of 0.0847 min –1 in the examination. Therefore, applying the suitable calcination duration ensures the good catalytic efficiency of the material as well as proposes an economical aspect in timing and energy usage, eventually reducing costs and expanding the practical application in phototreatment on a mass scale …”