Spray-dried Ni-Co Bimetallic Catalysts for Dry Reforming of Methane

Dry reforming of methane (DRM) is an attractive reaction for synthesis gas production, since it converts two greenhouse gases into valuable chemical feedstock. Silica supported bimetallic catalysts with constant metal loading but varying Ni/Co ratios (xNi=1, 0.8, 0.6, 0.5, 0.4, 0.2, 0) were produced via spray-drying for the application in DRM, aiming at the identification of compositions with superior activity. In this study, building block particles refer to an inert framework, supporting the catalyst. The elemental distribution of Si, Ni, and Co within such building block particles was evaluated using scanning transmission electron microscopy. Additionally, X-ray diffraction and temperature-programmed reduction experiments confirmed that Ni and Co initially exist in an oxidic state within the SiO2 framework after production and later transform into an alloyed metallic state upon reduction with hydrogen, as confirmed by X-ray photoelectron spectroscopy. A systematic comparison of the activity over a temperature range (323-1150 K) was performed using temperature scanning measurements. The highest intrinsic activity was found with the bimetallic Ni40Co60 particles. This study examines the potential of spray-dried bimetallic Ni-Co/SiO2 catalyst nanoparticles for the Dry Reforming of Methane (DRM). Applying temperature scanning experiments (TPR, TPD, TPO) and accompanying offline diagnostics (STEM-EDXS, BET, XRD, XPS), Ni/Co ratios were identified with a superior activity and high specific metal surface area. Remarkably high TOFs were found for particles with compositions between Ni80Co20 and Ni40Co60. image