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在富氧条件下分别以含氧有机物甲醇、乙醇、乙醛和乙酸等为还原剂 ,考察了Ag/Al2 O3 对NOx 选择性催化还原的活性 .结果表明 ,当银负载量为 4 %时 ,催化剂具有最高的催化活性 .在整个实验温度范围内 ,乙醇较丙烯具有更高的还原NOx的活性 ,且操作温度范围更宽 (30 0～ 6 10℃ ) ,NOx 脱除率可高达 90 % ,更加适合柴油机尾气中NOx 的净化 .添加 10 %的水可提高乙醇还原NOx 的低温活性 .随着乙醇浓度的增加 ,NOx 转化率显著提高 .在相同的浓度下 ,甲醇和乙酸还原脱除NOx 的效率较低 ;而乙醛还原脱除NOx 的效率与乙醇相当 .原位红外光谱研究结果表明 ,反应过程中生成大量吸附态的烯醇式物种(CH2 ∶CHO-)是乙醇和乙醛呈现较高还原活性的主要原因
The catalytic activities of Ag / Al 2 O 3 for selective catalytic reduction of NOx were investigated under oxygen-rich conditions using oxygen-containing organic compounds such as methanol, ethanol, acetaldehyde and acetic acid as reductants, respectively. The results showed that when Ag loading was 4% The catalyst has the highest catalytic activity.Within the whole experimental temperature range, ethanol has higher NOx reduction activity than propylene, and the operating temperature range is wider (30 0 ~ 6 10 ℃) and the NOx removal rate can reach as high as 90% Which is more suitable for the purification of NOx in the exhaust of diesel engine.Adding 10% water can improve the low temperature activity of ethanol reduction of NOx.With the increase of ethanol concentration, the conversion of NOx is significantly increased.At the same concentration, the reduction of NOx by methanol and acetic acid And the efficiency of acetaldehyde reduction is similar to that of ethanol.The results of in situ FT-IR showed that a large number of enolic species (CH2: CHO-) High reduction activity of the main reasons