Nanostructured Ru-Co@SiO₂: Highly efficient yet durable for CO₂ reforming of methane with a desirable H₂/CO ratio

In this study, the nanostructured bimetallic Ru-Co catalysts (Ru-Co core particles of ca. 50 nm; SiO₂ sell thickness of 6.1 nm, and n_Ru/n_Co = 0.008) were fabricated through the hydrothermal (or impregnation) and modified Stöber processes. The developed catalysts were characterized by means of XRD, N₂ sorption, TEM, XPS, TG-MS, and H₂-TPR, and evaluated for CO₂ reforming of methane to syngas, to establish a detailed structure-performance correlation. The strategy of catalyst design effectively reduced metal sintering at reaction temperatures. Uniform Ru distribution through a hydrothermal approach resulted in more direct Co-Ru interaction, which caused the Co-based cores rather coking- and oxidation-resistant, and induced a phase transformation of β-Co to α-Co under the reaction atmosphere, beneficial for the reaction. The silica shell porosity was modified by applying the CTAB and PVP surfactants in shell encapsulation. In terms of reaction temperature (700 °C), CH₄ turnover frequency (84.3 s⁻¹), H₂/CO ratio (0.98), and carbon deposition rate (0.5 mg_coke g_cat⁻¹ h⁻¹), the currently developed binary Ru-Co catalyst with uniform Ru distribution and improved SiO₂ shell porosity is proved to be highly efficient yet durable with a desirable H₂/CO ratio for the target reaction. In view of the unique features of catalyst material and the outstanding reaction performance on the basis of CH₄ TOF, new insights into the Co-based catalyst for DRM are provided in the current work.