富氧条件下Ag、Co和Cu/Al2O3选择性催化还原NO的研究

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%多.

Selective Catalytic Reduction of NO on Ag, Co and Cu/Al2O3 in Excess Oxygen

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 N2 (approximately 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%.