Role of cobalt on γ-Al 2 O 3 based NO x storage catalyst

Co/Pt/Ba/γ-Al 2 O 3 , Co/Ba/γ-Al 2 O 3 , Pt/Ba/γ-Al 2 O 3 , Co/Pt/γ-Al 2 O 3 , Ba/γ-Al 2 O 3 , Pt/γ-Al 2 O 3 , and Co/γ-Al 2 O 3 type catalysts were prepared by a conventional impregnation method, and their NO x 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 NO x storage for Co-containing catalysts including Co/Ba/γ-Al 2 O 3 and Co/Pt/Ba/γ-Al 2 O 3 is mainly due to the formation of Co 3 O 4 on the catalyst surface identified by XAFS.