富氧条件下Ag、Co和Cu/Al_2O_3选择性催化还原NO的研究

Selective Catalytic Reduction of NO on Ag, Co and Cu/Al_2O_3 in Excess Oxygen

研究了负载于氧化铝载体上的Ag、Co和Cu 3种金属催化剂在富氧条件下以丙烯为还原剂 ,选择性催化还原NO的活性 ,考察了这 3种金属单独负载时其负载量与活性的关系 ,并尝试探讨了这几种金属活性组分之间的一些组合效应 .研究表明 ,单组分催化剂以Ag的活性最佳 ,达近 90 % ,Co其次 ,Cu最低 .相应的最佳活性温度则是Cu最低 ,Ag最高 .对于单组分Ag催化剂 ,相同负载量的分步浸渍与一步浸渍样品活性无明显差异 .机械混合样品的活性不是单组分样品活性的简单加和 .其中 ,以Ag Co机械混合样品的活性最佳 ,最高活性高于 80 % .复合催化剂一步浸渍与分步浸渍样品的活性均有不同程度的下降 ,一步浸渍的几个样品的活性下降尤为明显 ,最高活性只有 30

The catalytic activities of alumina supported Ag, Co and Cu for selective reduction of NO with propene as reductant in the presence of excess oxygen were investigated. The catalytic performances of single component catalysts with different metal loadings and of samples prepared by various methods such as mechanical mixing, one step impregnation, two step impregnation, etc. were studied. The experimental results showed that the Ag exhibited the highest conversion of NO to N 2 (～89% with 2% loading,wt.) among single component catalysts, the lower was Co, and the lowest was Cu. The sequence of the temperature for the maximum conversion was on the order of Cu<Co<Ag. For Ag catalysts, the activities between samples of identical loadings prepared by one step and two step impregnation were almost the same. The activities of mixed samples were not the simple sum of the single component catalysts. The mixed Ag Co sample possessed the highest activity (80% above). The activities of the combinatorial samples declined comparatively to some extent. The activities of one step impregnation samples descended more markedly and the highest conversion was only over 30%.