我国水泥、玻璃、陶瓷等建材行业产能占全球一半以上，建材行业已成为我国大气污染排放控制的重中之重。NH3选择性催化还原（NH3-SCR）脱硝技术是目前最有效的NOx排放控制技术，但建材行业的烟气特征复杂，水泥炉窑烟气往往具有高碱/重金属含量和高SO2浓度等特点，玻璃和陶瓷炉窑烟气往往还具有高卤素浓度的特点。若想将NH3-SCR脱硝技术应用于建材行业的NOx脱除，必须深入探究各项影响因素对SCR催化剂的影响机制及其协同作用，随后针对性地对催化剂进行改性，以满足实际需求。为此，本论文分别针对中低温（150~250 ℃）和高温（250~450 ℃）SCR脱硝催化剂，深入探究了建材行业复杂烟气特征下催化剂的反应机制和中毒过程。取得如下创新成果： （1）针对低温Mn基SCR催化剂，烟气中HCl的Cl离子倾向于吸附在MnCe表面Mn离子附近的氧空位上，吸附的Cl离子还进一步促进了MnCe表面氧空位的形成。因此，当烟气中存在HCl时，MnCe表面的活性位点Mn将被Cl离子快速覆盖形成MnCl2，抑制催化剂的氧化还原能力和Mn2+ + Ce4+ ? Mn3+?Ce3+氧化还原循环，从而显著抑制MnCe的低温SCR活性。烟气中SO2倾向于以“-Mn-O-S-O-Mn-”的结构形式吸附在Mn3O4和(Cu1.0Mn2.0)1-δO4催化剂表面。Cu的掺杂抑制了催化剂中相邻Mn位点的数量，因此Cu掺杂抑制了催化剂表面“-Mn-O-S-O-Mn-”结构（即MnSO4）的形成，从而显著提高了Mn3O4尖晶石的抗硫中毒能力。 （2）针对高温钒钛SCR催化剂，发现催化剂表面的碱金属可以与气态SO2和表面弱吸附的SO42-和HSO4-等物种反应生成体相SO42-物种（即K2SO4），这一强交互作用削弱了碱金属对活性位点V电子结构的影响，恢复了V-O键的反应活性。因此，当烟气中碱金属与酸性物质SO2同时存在时，对VTi催化剂的SCR反应活性影响小于单独SO2或K中毒对VTi催化剂的影响。 （3）借助DFT理论计算，发现Ce0.8Fe0.2催化剂的空间结构导致NH3倾向于倾斜吸附在Fe位点上，此时吸附态NH3的两个H原子靠近相邻O原子，形成了H键作用，削弱了N-H键的键能，促进了NH3活化为NH2的过程，使得整个反应循环的决速步由NH3活化转变为其他基元反应。这一效应是Ce0.8Fe0.2催化剂在氧化还原性和表面酸性最差的条件下表现出最优异SCR反应活性的本质原因。此外，这一效应普遍存在于Ce基双金属氧化物催化剂（如CeV、CeMn和CeCo）中。
China's cement, glass, ceramics and other building materials industry production capacity accounts for more than half of the world, building materials industry has become the top priority of air pollution emission control in China, especially the proportion of NOx emission from cement industry has leaped to the top of all industries. The selective catalytic reduction of NOx by NH3 (NH3-SCR) is the most effective NOx emission control technology at present. However, the characteristics of flue gas in building materials industry are complex. The fule gas of cement furnaces often have the characteristics of high alkali/heavy metal content and high SO2 concentration, while the flue gas of glass and ceramic furnaces have the characteristics of high halogen concentration in addtion. If we want to apply NH3-SCR De-NOx technology to building materials industry, the influence mechanism and synergy of various influencing factors on SCR catalyst should be deeply explored. Thus the catalyst can be modified to meet the actual demand. In this paper, the reaction mechanism and poisoning process of SCR catalysts under complex flue gas conditions in building materials industry were studied. The following innovative achievements have been achieved: (1) For low-temperature Mn based SCR catalysts, Cl ions in HCl tended to adsorb on oxygen vacancies near Mn ions on MnCe surface, and the adsorbed Cl ions further promoted the formation of oxygen vacancies on MnCe surface. Therefore, when HCl is present in the flue gas, the active site Mn on the surface of MnCe will be quickly covered by Cl ions to form MnCl2, which can inhibit the reducibility of the catalyst and the oxidation-reduction cycle of Mn2+ + Ce4+ ? Mn3+?Ce3+, thus significantly inhibiting the low-temperature SCR activity of MnCe. SO2 tended to adsorb on the surface of Mn3O4 and (Cu1.0Mn2.0)1-δO4 catalysts in the form of “-Mn-O-S-O-Mn-”. Cu doping significantly inhibited the number of adjacent Mn sites in the catalyst, so Cu doping significantly inhibited the formation of “-Mn-O-S-O-Mn-” structure (MnSO4) on the surface of the catalyst, which significantly improved the sulfur poisoning resistance of Mn3O4 spinel at low temperature SCR. (2) For high-temperature VTi SCR catalyst, the alkali metals on the surface high temperature SCR catalyst could react with gaseous SO2 and S species such as surface SO42- and HSO4- to form bulk SO42- species (K2SO4). This strong interaction weakened the effect of alkali metals on the electronic structure of the active site V, and thus restored the reactivity of V-O bond. Therefore, the presence of alkali metals and SO2 in flue gas only has a little effect on the SCR activity of VTi catalyst, even less than that of SO2 poisoning alone. (3) Based on the DFT theory calculation method, we found that the space structure of Ce0.8Fe0.2 catalyst led to the inclined adsorption of NH3 on Fe sites. At this time, the two H atoms of NH3 were close to the adjacent O atoms, thus forming H-bond and weakening the bond energy of N-H bond. The weakening of N-H bond could promote the process of NH3 activation to NH2, which makes the rate-determining step of the whole reaction cycle changed from NH3 activation to other elementary reactions. This effect is the essential reason why Ce0.8Fe0.2 has the best SCR activity under the condition of the worst reducibility and surface acidity. In addition, this effect is common in Ce based bimetallic oxide catalysts, such as CeV, CeMn and CeCo.
