Role of Ruthenium in Modified CeNi_1–<i>x</i>Ru_<i>x</i>O₃ Perovskite Catalysts for the Bireforming of Methane

The study on modifying catalytic properties by partially substituting nickel with ruthenium on the perovskite precursor CeNiO3 has been conducted in this work. Catalysts were synthesized using a coprecipitation method, and their physicochemical properties were evaluated through analytical techniques, including X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), H2 temperature-programmed reduction (H2-TPR), CO2 temperature-programmed desorption (CO2-TPD), and Raman spectroscopy. Additionally, thermogravimetric analysis coupled with differential scanning calorimetry (TGA-DSC) and XRD were employed to assess the carbon deposition and coke type on the catalyst after 100 h TOS. All ruthenium-modified CeNi1–xRuxO3 (x = 0.01, 0.05, and 0.10) catalysts showed good activity with CH4 and CO2 conversion rates exceeding 90% at 700 °C. Ru modification facilitated the incorporation of Ni and Ru into the ceria lattice, resulting in the formation of Ru–O–Ce and Ni–O–Ce bonds, which significantly enhanced the catalyst’s sintering resistance and Ni reducibility. Moreover, the Ru-modified catalyst exhibited a considerable increase in specific surface area, reduced Ni crystallite size, emergence of highly active basic sites, and an increase in oxygen vacancies. However, excessively loading Ru lowers the Ni dispersion, resulting in metal agglomeration and decreased catalytic activity. The optimal substitution ratio of Ru was determined to be 0.05. Catalyst CeNi0.95Ru0.05O3 showed the highest BRM activity with conversion of both CH4 and CO2 of approximately 95% at 700 °C, compared to 88 and 90%, respectively, for CeNiO3 catalysts. The CeNi0.95Ru0.05O3 catalyst maintained good stability after 100 h of reaction with a 3 times lower coke accumulation rate compared to bare CeNiO3 perovskite. Thus, partially substituting Ru into the perovskite structure of CeNiO3 emerges as an effective strategy to improve the activity, durability, coke resistance, and sintering of the Ni catalyst in methane reforming reactions.