【摘要】 采用改进的溶胶 凝胶法制备了Ba Fe O(Ba/Fe原子比为 0 5 ) ,Ba Ce O(Ba/Ce原子比为 1)和Ba Sn O(Ba/Sn原子比为1)氧化物 ,并考察了其储氮性能 .结果表明 ,75 0℃焙烧的Ba Fe O样品 ,在 4 0 0℃下的NOx 储存容量 (NSC)最大 ,其次为 90 0℃焙烧的Ba Ce O样品 ;相同温度焙烧的样品 ,在 4 0 0℃下的NSC均大于 2 0 0℃下的NSC .XRD测试结果表明 ,75 0℃焙烧的Ba Fe O样品的缺陷钙钛矿BaFeO3 δ可能是储存NOx 的主要活性相 ,而Ba Ce O和Ba Sn O样品储存NOx 的活性相分别为钙钛矿型BaCeO3 和BaSnO3 .BET测定结果表明 ,样品的比表面积均较小 .用FT IR分析了Ba Fe O样品上储存的NOx 物种 .讨论了NSC大小与吸收温度、NOx 吸收物种及样品物相之间的关系更多还原

【Abstract】 Under lean conditions, NO x is oxidized into nitrite or nitrate and adsorbed or absorbed on the alkaline components (Ba, Sr, Ca, Li, K and La) of catalysts, and then NO x is reduced to N 2 and released under rich conditions. The key point of this kind of catalysts is to have high efficiency of storage release nitrogen and resistance to SO 2 poison for practical purpose. The BaSnO 3 perovskite type catalyst possesses high NO x storage capacity (NSC) and resistance to SO 2 poison. The Ba Fe O ( n (Ba) / n (Fe) =0 5) and Ba Ce O ( n (Ba) / n (Ce) =1) perovskite type oxides were prepared by improved sol gel method and the Ba Sn O ( n (Ba) / n (Sn) =1) oxide as referential sample was prepared according to literature. The NO x storage property of Ba Fe O and Ba Ce O oxides was mainly examined by XRD, BET, FT IR and NSC measurement. The NSC of Ba Fe O sample calcined at 750 ℃ is the highest (114 7 μmol/g ) at 400 ℃, the NSC of Ba Ce O sample calcined at 900 ℃ comes second (56 8 μmol/g ). However, the NSC of BaSnO 3 is only 7 31 μmol/g . The NSC of all the samples is higher at 400 ℃ than that at 200 ℃ when the calcination temperature is the same. The main phases of all the three samples are perovskite type structure. The defect perovskite BaFeO 3 δ of Ba Fe O sample calcined at 750 ℃ may be the main active phase for NO x storage, however, the active phase of Ba Ce O and Ba Sn O samples for NO x storage may be the perfect BaCeO 3 and BaSnO 3 perovskite phase respectively. The specific surface area of all the samples is smaller than 10 m 2/g except Ba Sn O sample. The adsorbed and absorbed NO x species were characterized. Both the nitrite and the nitrate appear after NO x is adsorbed and absorbed at 200 ℃, whereas the nitrite disappears and the nitrate increases at 400 ℃. The NO x absorption is beneficial to NO x oxidation to form nitrate with alkaline Ba 2+ ions at 400 ℃, while the nitrite is unstable. The relationship of NSC with absorption temperature, absorbed NO x species or oxide structure is also discussed.更多还原