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

The catalytic performances of Ni/CeO2–Al2O3 catalysts for the dry reforming of CH4 (DRM) were investigated. Catalysts with different Ni dispersion and different amounts of CeAlO3 species were prepared by different methods and characterized by BET, XRD, XPS, Raman, TPR, and TPO techniques. Catalytic activity was studied during the time on stream in the range 873–1073K 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 increase of Ni crystallite size. Carbon was deposited as nano-fibers and graphite when catalysts worked at lower temperatures, 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 obtaining 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.