The Study of the NOx Storage Mechanism and Property of the Catalyst Pt/Ba-Al-O

The NOxstorage catalyst Pt/Ba-Al-O was prepared by co-precipitation method. The sample was characterized by XRD, NO-TPD and NSC. The barium in the sample mainly exists as BaAl2O4except few BaCO3phase. Two kinds of Pt sites seem to operate. The NO-TPD peak at about 270℃corresponds to sites 1 and the other peak at about 500℃corresponds to sites 2. Sites 1 are responsible for NO adsorption and sites 2 are responsible for nitrate and nitrite formation. When the sample adsorbed NO at 300℃with 1.3% O2, the NO desorption from the sample reached the maximum. When the adsorption was carried out over a prereduced surface, the sample had a much better NOxstorage capacity than that over a preoxidized surface. The NSC results indicate that the optimum temperature region for NOxstorage is 300~450℃.