氧化改性活性炭催化脱除NO的性能

Catalytic activity of oxidized modified activated carbon on NO removal

将活性炭(AC)应用于烟气脱硝中,其自身损耗和脱硝效率是关注焦点。采用不同氧化剂(KMnO_4、HNO_3、(NH_4)_2S_2O_8和H_2O_2)对AC进行氧化改性,对所得催化剂进行了TG、FTIR、H_2-TPR和XPS表征,并对其脱NO活性进行了评价。对AC进行浸渍回流处理,可使AC表面含氧官能团增加,尤其是羧基和羰基等酸性含氧官能团。TG分析结果表明:在没有O_2存在时,催化剂表面的O会与NO发生反应,导致催化剂自身损耗;在O_2存在时,NO主要与O_2中的O反应,因而在一定温度范围内不会发生催化剂自身损耗;同时AC表面的含氧官能团能加速NO的化学吸附活化,从而提高催化剂的脱NO活性。KMnO_4改性的AC在180℃具有高催化活性,这归因于催化剂表面丰富的含氧官能团以及高价态Mn的存在。

When activated carbon（AC） is applied in flue gas denitration,its mass loss and denitration efficiency are the focus of attention. AC was modified using different oxidation agents,such as KMnO4,HNO3,（NH4）2S2O8 and H2O2,and was characterized by TG,FTIR,H2-TPR and XPS. The catalytic activities of these catalysts on NO removal were evaluated. The oxygen-containing functional groups on AC surface,especially acidic groups such as carboxyl and carbonyl,will be increased by impregnation reflux treatment. The TG analysis results show that：O atom on the catalyst surface will react with NO in the absence of O2,leading to loss of catalyst;But in the presence of O2,NO will mainly react with O atom of O2,therefore the loss of catalyst will not happen in a certain temperature range;At the same time,the oxygen-containing functional groups on AC surface can accelerate the chemical adsorption and activation of NO and improve the catalytic activity of the catalyst on NO removal. The KMnO4-modified AC had high catalytic activity at 180 ℃,which was attributed to the existence of rich oxygen-containing functional groups and high valence Mn on the catalyst surface.