Molybdenum species on alumina and silica supports for soot combustion

Mo/Al2O3 and Mo/SiO2 catalysts with different molybdenum species were tested in diesel soot combustion. These catalysts have shown different performances due to the presence of different species, being the most active those dispersed onto silica surface, which are similar to Mo2O72- ion. The thermal stability was evaluated by differential thermal analyses and the results have shown that Mo species formed on silica-supported catalysts are thermally stable under the reaction conditions. The performance of Mo/SiO2 catalyst may be attributed to the contact between these species and the soot and not to the MoO3 vapor originated by a weak interaction of these species with the silica support.