烟气气相组分及Ca(OH)_2对KMnO_4氧化NO的影响机理

Mechanism of influence of flue gas components and Ca(OH)_2 on oxidation of NO over KMnO_4

在固定床反应器中考察了KMnO4氧化烟气中NO的过程,分析了烟气组分H2O、O2及SO2对NO氧化过程的影响规律,得到了Ca(OH)2对KMnO4氧化NO的影响机理。实验结果表明,H2O是KMnO4氧化NO的必要条件;在含H2O条件下,O2可以提高NO氧化率。SO2与氧化剂反应生成无水钾镁钒类复盐K2Mn2(SO4)3对NO氧化具有负面作用;Ca(OH)2的加入提高了氧化剂表面的固体碱度从而促进氧化过程进行;通过添加Ca(OH)2可以降低SO2对NO氧化过程的负面影响。根据气体成分和产物分析可知,KMnO4在钙基吸收剂表面氧化烟气中NO的机理可能是KMnO4以离子态将吸附在氧化剂表面的NO和SO2氧化为NO2和SO3,生成的NO2、SO3再传递到氧化位临近的碱性位被吸收。

The processes of oxidation of NO from flue gas of coal combustion over KMnO4 was studied in the fixed bed reactor at a low temperature.The effect of flue gas components,such as SO2,H2O and O2,on the oxidation of NO was analysed.The influence mechanism of Ca（OH）2 on oxidation of NO over KMnO4 was proposed.The presence of H2O was found to be necessary for the oxidation of NO to NO2 over KMnO4.SO2 was absorbed as K2Mn2（SO4）3 by KMnO4,which restrained the oxidation of NO.The addition of Ca（OH）2 into KMnO4 couldincrease the solid alkalinity of KMnO4 surface and enhance the oxidation of NO. Ca（OH）2 could weaken the inhibition of oxidation of NO by SO2. The results of XRD analysis of the products and the components of flue gas from reactor outlet showed the oxidation mechanism of NO over KMnO4 that the NO and SO2 firstly reacted with KMnO4 in the presence of H2O, and then were transferred to alkaline site and absorbed.