Rh-CeO2-Al2O3 catalysts for the Partial Oxidation of Methane: effect of Ce content on catalyst properties

PATRICIA BENITO MARTIN; ADRIANA D. BALLARINI; LORENZO VALENTINI; GIUSEPPE FORNASARI; FRANCESCA OSPITALI; OSVALDO A. SCELZA.; ANGELO VACCARI

Congreso; XXIV Congreso Iberoamericano de Catálisis.; 2014

Bulk Rh-CeO2-Al2O3 catalysts (0.25 wt.% Rh) have been prepared by coprecipitation and tested in the catalytic partial oxidation of CH4 to produce syngas (CO + H2). The role of Ce loading (0-20 wt.%) on chemical-physical and catalytic properties has been investigated. The larger the Ce content the lower the catalyst surface area, rhodium reducibility and dispersion; consequently CH4 conversion and syngas selectivity decrease. The oxidation state of Ce in reduced samples depends on the loading: in 5wt.% Ce catalyst only Ce3+ has been identified, while both Ce3+ and Ce4+ are found in 20wt.% Ce sample. After catalytic tests, regardless of the loading, Ce is reduced to Ce3+; moreover, in 20wt.% Ce catalyst a well-defined CeAlO3 phase is identified. The deposition of carbon and the formation of α-Al2O3 do not occur in Rh-CeO2-Al2O3 catalysts.