Pt/Ba-Al-O催化剂储存NOx的性能和机理研究

采用共沉淀法制备了Pt/Ba-Al-O样品.用XRD、 NO-TPD以及NOx储存量测量等手段对样品进行了表征, 并对NOx的储存机理进行了探讨.结果表明, 样品中的主要成分是BaAl2O4, 有少量BaCO3存在.在催化剂表面的Pt有两种吸附位,吸附位1为NO提供了吸附位,对应低温区的NO脱附峰;吸附位2使NO和O2在催化剂表面反应生成硝酸盐和亚硝酸盐,对应高温区的NO脱附峰.当吸附温度为300℃、 O2的体积分数为1.3%时, NO的脱附量达到了最大值.经过还原处理样品的NO吸附能力比经过氧化预处理的样品强得多.样品储存NOx的最佳温区为300～450℃.

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℃.