Role of cobalt on γ-Al₂O₃ based NO _x storage catalyst

Co/Pt/Ba/gamma-Al2O3, Co/Ba/gamma-Al2O3, Pt/Ba/gamma-Al2O3, Co/Pt/gamma-Al2O3, Ba/gamma-Al2O3, Pt/gamma-Al2O3, and Co/gamma-Al2O3 type catalysts were prepared by a conventional impregnation method, and their NOx storage capacities were evaluated by colorimetric assay. Co-containing catalysts had a higher NO (x) storage capacity than that of Co-free counterparts. The role of each component, especially Co, for the catalysts prepared was investigated by using in-situ FTIR. The high NOx storage for Co-containing catalysts including Co/Ba/gamma-Al2O3 and Co/Pt/Ba/gamma-Al2O3 is mainly due to the formation of Co3O4 on the catalyst surface identified by XAFS.