MnFeO_x催化剂低温催化氧化NO

Low-temperature Catalytic Oxidation of NO by MnFeO_x Catalyst

采用有机溶剂法制备非负载型MnFeOx催化剂,用于低温选择性催化氧化NO。研究了催化剂前驱体、Mn^7+∶Mn^2+摩尔比、制备方法等对低温催化氧化NO的影响。实验结果表明,Mn(CH 3 COO)2作为催化剂前驱体较其它三种物质更有利于提高NO的转化率;Mn^7+∶Mn^2+=2∶1时低温脱硝性能较优;与共沉淀法比较,有机溶剂法制备的MnFeOx催化剂低温催化氧化活性较好,NO的转化率达到83%。结合扫描电子显微镜(SEM)、X射线衍射仪(XRD)、比表面积测定仪(BET)、X射线光电子能谱仪(XPS)、H 2程序升温还原(H 2-TPR)表征手段分析,Mn和Fe元素在Mn(CH 3 COO)2作为前驱体的催化剂表面上分散均匀,催化剂脱硝性能提高;随着Mn^7+∶Mn^2+摩尔比增加,催化剂内部发生团聚,比表面积和平均孔径逐渐减小,不利于低温选择性催化氧化反应;同时,NO的催化活性受结晶度的影响,有机溶剂法制备的MnFeOx催化剂结晶度低,具有较多氧空穴,有利于低温脱硝。

The non-supported MnFeOx catalyst was prepared by organic solvent method for low-temperature selective catalytic oxidation of NO.The effects of catalyst precursors,Mn^7+∶Mn^2+molar ratio and preparation methods on the catalytic oxidation of NO at low temperature were investigated.The experimental results show that Mn(CH 3 COO)2 as catalyst precursor is more beneficial to improve the conversion of NO than other three substances.When the molar ratio of Mn^7+∶Mn^2+is 2∶1,the lower-temperature de-NOx activity is better.The MnFeOx catalyst prepared by the organic solvent method has good catalytic activity at low temperature than that of the coprecipitation method,and the conversion rate of NO reaches 83%.The catalyst samples were characterized by scanning electron microscopy(SEM),X-ray diffractometry(XRD),specific surface area analyzer(BET),X-ray photoelectron spectrometry and Hydrogen temperature programmed reduction(H 2-TPR).The results indicate that the Mn and Fe elements are uniformly dispersed on the surface of the catalyst with Mn(CH 3 COO)2 as catalyst precursor,and the de-NOx activity increases.With the increase of the molar ratio of Mn^7+∶Mn^2+,the agglomeration occurr inside the catalyst,and the specific surface area and average pore diameter gradually decreases,leading to lower de-NOx activity.In addition,the catalytic activity of NO is affected by crystallinity,and the catalyst with amorphous structure has more oxygen holes,which is beneficial to low-temperature de-NOx activity.