NO_x储存催化剂Pt/Ba-Al-O的结构与性能研究

Study of the Structure and Property of NO_x Storage Catalyst Pt/Ba-Al-O

采用共沉淀和浸渍法 ,制备了不同焙烧温度、不同 Al/Ba原子比的 Pt/Ba- Al- O系列催化剂样品 . BET结果表明 ,所得样品具有较高的比表面积 ;若焙烧温度相同 ,则比表面积随着样品中 Ba含量的减小而增加 .XRD结果表明 ,载体 Ba- Al- O经过 10 0 0℃焙烧后 ,Ba主要以 Ba Al2 O4形式存在 ,所含 Ba CO3较少 ;于空气中陈放 10个月后 ,样品中 Ba Al2 O4的衍射峰强度显著下降 ,而 Ba CO3的衍射峰明显增强 .陈化样品经 80 0℃焙烧 2 h后 ,Ba Al2 O4相明显再生 . NO- TPD和 NSC结果均表明 ,新鲜的催化剂样品对 NOx 具有良好的储存性能 ,在有氧和较高温度 (2 0 0℃ )下 ,NO更易于被氧化 。

A series of Pt/Ba Al O catalysts(Al/Ba=8,12,16) were prepared by \{coprecipitation\|\}impregnation method. The supports Ba Al O were calcined at 800 ℃and 1 000 ℃, respectively. The samples were characterized by BET surface area(SA), X ray diffraction(XRD), NO TPD and measurement of NO x storage capacity (NSC). The highest SA is about 180 m 2/g among the Pt Ba Al\|O 800 samples and is about 114 m 2/g when calcined at 1 000 ℃. XRD analysis shows that barium in the Pt Ba Al\|O 1000 samples mainly exists as BaAl 2O 4 besides a trace of BaCO 3 phase. For the samples aged in air for 10 months, the peak intensities of BaCO 3 increase and BaAl 2O 4 decrease obviously. The aged samples can be regenerated by calcination at 800 ℃. NO TPD and NSC results show that the fresh samples have a better NO x storage capacity than the aged ones. At a higher temperature (200 ℃), NO x can be easily oxidized to nitrates in the presence of O\-2. As a result, BaAl\-2O\-4 is the primary NO x storage site of the samples.