高铝粉煤灰负载锰基催化剂的催化氧化NO性能研究

氮氧化物催化氧化是烟气脱硝技术的一个重要发展方向。本工作以具有球形镂空结构的预处理后高铝粉煤灰为载体，以硝酸锰为活性组分源，采用溶胶凝胶法制备锰基NO氧化催化剂，采用扫描电镜(SEM)、X射线衍射仪(XRD)、N2物理吸附、H2程序升温还原分析仪(H2-TPR)和X射线光电子能谱(XPS)等分析测试手段对催化剂的NO催化氧化性能进行深入研究。结果表明，载体粒径、锰负载量、硝酸锰凝胶煅烧温度以及NO催化氧化温度对催化剂催化活性均有较大影响。当载体粒径在100~200目(150~75 μm)、锰负载量为8wt%、硝酸锰凝胶煅烧温度为500℃、NO催化氧化温度290℃时，NO催化氧化效果最好，氧化率达到77.8%。SEM结果显示，溶胶凝胶法制备的氧化锰粒子在100~200 nm，且相对均匀负载在载体上。N2-物理吸附表明，催化剂的孔结构主要为介孔，并呈现H3型回滞环。锰基催化剂上化学吸附氧Oβ的占比和Mn4+浓度随着锰负载量的增加先增大后减小，此趋势与NO催化性能变化趋势一致，表明Oβ和Mn4+是影响NO催化氧化效果的决定因素。

Study on NO catalytic oxidation by manganese-based catalysts supported on high alumina fly ash

Catalytic oxidation of nitrogen oxides is an important development direction of flue gas denitration technology. In this work, manganese-based NO oxidation catalysts were prepared by sol-gel method using the high alumina fly ash with spherical hollow structure as the carrier, and manganese nitrate as the source of the active component. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), N2 physical adsorption, H2 programmed temperature analyzer (H2-TPR), and X-ray photoelectron spectroscopy (XPS) were used to analyze the catalyst performance and NO catalytic oxidation mechanism. The results showed that the particle size of the carrier, manganese loading, calcination temperature of manganese nitrate gel, and the catalytic oxidation temperature of NO had a great influence on the catalytic activity of the catalyst. The optimum temperature for calcining manganese nitrate gel was determined to be 500℃. The best catalytic oxidation effect with an oxidation rate of 77.8% at the NO catalytic oxidation reaction temperature of 290℃ was obtained when the particle size of the carrier is between 100~200 mesh and the manganese mass loading was 8wt%. SEM results showed that the manganese oxide particle diameters prepared by the sol-gel method were between 100~200 nm and relatively uniformly loaded on the carrier. N2 physical adsorption showed that the pore structures of the catalyst were mainly mesoporous and exhibit an H3 hysteresis loop. Chemisorption of oxygen Oβ proportion on manganese-based catalysts and Mn4+ concentration firstly increased with the increase of manganese loading and then decreased. This was consistent with the trend of catalytic oxidation performance, indicating that Oβ and Mn4+ are the decisive factors affecting the catalytic oxidation of NO.