Packed and Monolithic Reactors for the Dry Reforming of Methane: Ni Supported on γ-Al2O3 Promoted by Ru

The CO2 reforming of CH4 or dry reforming (DRM) is as an efficient way for the CH4 and CO2 valorisation. The DRM plays also an important role on the electrochemical performances and the long-term stability of solid oxide fuel cells (SOFCs) fed by CH4 or biogas. Nickel is so far the most active catalyst for the DRM, but also highly prone to carbon formation, because, together with the ability to activate the C-H bond, Ni has high affinity to carbon. The Ni particle size has a strong effect on the carbon tolerance of the catalyst, therefore, the stabilization of small Ni nanoparticles at high temperatures is a promising way for the lifetime increase [1, 2]. Another strategy is the addition of a second metal (i.e Ru, Pt, Cu, Co) resulting in the formation of less C-sensitive alloys or in the increase of Ni dispersion. The development of structured and unstructured catalysts for DRM based on Ni nanoparticles (10 wt%) supported on γ-Al2O3 promoted by a small amount of Ru (0.05 wt%), has been investigated. Unstructured catalysts (packed powder) were prepared by wet impregnation method and a combination of wash coating-wet impregnation methods was used for structured catalysts (cordierite monoliths). Samples were characterized by XRD, BET, H2-TPR, TEM and FE-SEM techniques and the catalytic activity for DRM was studied at 800 °C during time on stream with a mixture of CH4:CO2:Ar=45:45:10 vol.% and a gas space hourly velocity GHSV=11400 h-1 (150 cm3 min-1) Morphological analysis confirmed that a large amount of carbon filament was deposited on Ni catalyst mainly by a tip growth mechanism, whereas on Ni-Ru, few carbon filaments were deposited with a base growth mechanism mainly in the inlet region. Moreover, the comparison between structured and unstructured catalyst underlined the advantages of structured catalysts over conventional packed bed reactors such as: increased mass and heat transfer, lower pressure drop, larger surface to-volume ratio and compact reactor design.