Ni/CeO2–Al2O3 catalysts for the dry reforming of methane: The effect of CeAlO3 content and nickel crystallite size on catalytic activity and coke resistance

• Specific catalytic activity for the DRM increases with the nickel crystallite size.
• Carbon deposits are greater on catalysts with larger Ni crystallite size.
• CeAlO3 suppressed the deposition of graphite-like coke.
• CeAlO3 is formed by reduction of CeO2−x species well dispersed on γ-Al2O3.
• The citric acid method promotes small Ni crystallite and the formation of CeAlO3.

The catalytic performances of Ni/CeO2–Al2O3 catalysts for the dry reforming of CH4 (DRM) were investigated. Catalysts with different Ni dispersion and different amount of CeAlO3 species were prepared by different methods and characterized by BET, XRD, XPS, Raman, TPR and TPO techniques. Catalytic activity was studied during time on stream in the range 873–1073 K with a mixture of CH4:CO2:Ar = 40:40:20 vol.% and GHSV 90,000 cm3 g−1 h−1. The intrinsic catalytic activity increased with the increasing of Ni crystallite size. Carbon was deposited as nano-fibres and graphite when catalysts worked at lower temperature, and the largest amount was found on the catalyst with the largest Ni crystallite size. The formation of graphitic deposits is limited by the presence of CeAlO3 species formed during catalyst activation. CA preparation method results particularly attractive because it allows to obtain catalysts with small Ni crystallite size and high content of CeAlO3 species, which both have a role in suppressing the carbon deposition and therefore in obtaining stable catalytic performances.

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