不同元素掺杂锰基催化剂的NH_(3)-SCR反应性能研究

Study on NH_(3)-SCR performance of manganese based catalysts doped with different elements

为了研究催化剂的酸碱性和氧化还原能力对纯锰氧化物催化剂的NH^(3)-SCR(选择性催化还原)反应性能影响,选取碱土金属Sr、过渡金属Ce、Fe和非金属Si对纯锰氧化物催化剂进行改性,所有催化剂均采用共沉淀法制取。通过XRD、N_(2)-BET、NH_(3)-TPD、XPS和H_(2)-TPR表征手段对催化剂进行分析。XRD结果表明,实验采用的制备方法制备的锰基催化剂主要物相为Mn_(2)O_(3)和Mn_(5)O_(8);N_(2)-BET结果显示,Ce、Fe、Si3种元素能有效增加纯锰氧化物的比表面积;NH_(3)-TPD和XPS结果证明,Ce、Fe、Si的引入使得纯锰氧化物的表面吸附氧(O_(Ⅱ))、Mn^(4+)含量提高,Ce和Si的掺杂增加了催化剂的总酸量,Fe则有效调控了酸性位的分布;H_(2)-TPR结果表明,除Ce外其余元素均使纯锰氧化物催化剂的氧化还原能力有所减弱。对所有催化剂在100~400℃进行脱硝活性测试,MnCeO_(x)表现出优异的低温脱硝活性,MnSiO_(x)表现出不错的中高温脱硝活性。

In order to study the influence of the acid-base and redox capacity of the catalyst on the NH_(3)-SCR performance of pure manganese oxide catalyst,the alkaline earth metals of Sr,transition metals of Ce,Fe and nonmetal of Si were selected to modify the pure manganese oxide catalyst.All catalysts were prepared by coprecipitation method.The catalysts were characterized by XRD,N_(2)-BET,NH_(3)-TPD,XPS and H_(2)-TPR.The XRD results showed that the main phases of the manganese-based catalyst prepared by the method used in this experiment were Mn_(2)O_(3) and Mn_(5)O_(8).The N_(2)-BET results showed that Ce、Fe、Si could effectively increase the specific surface area of pure manganese oxides.The NH_(3)-TPD and XPS showed that the introduction of Ce、Fe、Si increased the content of oxygen(O_(Ⅱ))and Mn^(4+)on the surface of pure manganese oxides,the doping of Ce and Si increased the total acid content of the catalyst,and Fe effectively regulated the distribution of acid sites.The H_(2)-TPR showed that all the elements except Ce weakened the redox capacity of pure manganese oxide catalyst.The denitrification activity of all catalysts was tested at 100~400℃.MnCeO_(x) showed excellent denitrification activity at low temperature and MnSiO_(x) showed good denitrification activity at medium and high temperature.