SCR板式脱硝催化剂的工艺与性能研究

发布时间：2018-07-09 18:58

  本文选题：板式催化剂 + 成型工艺　； 参考：《江苏科技大学》2014年硕士论文

【摘要】：近年来，氮氧化合物（NOx）对环境已经造成严重的危害，目前选择性催化还原（SCR）法是最有效的De-NOx技术。SCR技术的核心是脱硝催化剂，中温蜂窝式脱硝催化剂已在世界范围内被广泛地应用，但中温蜂窝式脱硝催化剂的抗堵塞和抗磨损性能较差，因此不适合在高灰分条件下的使用；而板式脱硝催化剂具有优良的抗堵、抗磨损等性能，可在高灰分条件下顺利地运行。板式脱硝催化剂的制备工艺被日本、欧美等国家垄断，虽然近几年，国内的科研院所致力于板式催化剂成型工艺和配方的研究，但是目前尚无自主知识产权的、可以用于工业生产的板式脱硝催化剂的生产线，因此立项对板式脱硝催化剂成型工艺及配方的研究有重大意义。本课题采用辊压的方法制备板式脱硝催化剂，辊压成型法的成型效率高于液压机压制成型法。 近年来我国着重解决大气污染治理问题，一再提高烟气的硫硝排放标准，因此对SCR脱硝催化剂的需求量及品质要求越来越高。催化剂的载体材料TiO2占催化剂总含量80%以上，并且国产的催化剂载体材料鱼龙混杂，因此对载体材料进行针对性研究并提出一定的评价依据十分必要。鉴于此，本课题选取了三种国产载体材料HTm、PB1m、PB2m，并采用半浸渍法制备了HT、PB1、PB2系列催化剂泥料，然后将泥料通过24小时的密封陈腐，由自行设计的板式成型机进行成型，最后将成型催化剂经室温-60℃程序升温干燥5天，60-610℃程序升温焙烧33小时。对所制备的板式脱硝催化剂在模拟烟气条件下进行脱硝活性检测，并采用BET、Raman、XPS、TPR表征方法检测分析国内常见的TiO2-WO3-SO42-型载体材料的性能及其对所制备的催化剂脱硝效率的影响，为评价国产催化剂载体材料的品质提供一定的理论基础。分析讨论WOx与VOx之间的相互作用关系，以及WOx对VOx的改性作用机理。得出以下结论： 结果表明：自行设计的辊压板式成型机可以顺利地制备板式催化剂并且不存在开裂现象；当载体的比表面积太大时，虽然有利于降低VOx的聚合度，但同时促进孤立态VOx地形成，比表面积太小时，会使催化剂具有较低的比表面积，因此，，只有当载体的比表面积大小适宜时，最有利于脱硝反应；强B酸性位更容易吸附NH3，但是强B酸性位与NH3之间的电子作用力较强，导致中间产物不易分解，阻碍反应的顺利进行；W6+与VOx之间的电子效应远大于W5+，W6+的含量越高，越有利于提高WOx对VOx的改性作用；具有氧缺陷结构形式的W6+Ox，更容易与O结合，与VOx形成W-O-V式结构，因此，该结构的W6+Ox更容易与VOx发生电子作用，有利于WOx对VOx进行改性；载体表面WOx的聚合度越低，分散性越好，越有利于WOx与VOx的接触，有利于WOx对VOx的改性，促进脱硝反应；适度降低氧化位V5+=O中V的氧化态，可以有效抑制NH3和SO2氧化反应地发生；WOx与VOx之间存在着相互作用，两者不是孤立地存在于载体的表面，一方面，WOx可以通过在催化剂表面的占位效应，促进聚合态VOx地形成，另一方面，WOx可以与VOx发生电子作用形成W-O-V式结构，降低氧化位V5+=O的氧化性，同时抑制高聚合态VOx地形成。
[Abstract]:In recent years, nitrogen and oxygen compounds (NOx) have caused serious harm to the environment. At present, selective catalytic reduction (SCR) is the most effective De-NOx technology, the core of.SCR technology is denitrification catalyst. The medium temperature honeycomb type denitrification catalyst has been widely used worldwide, but the anti clogging and wear resistance of the medium temperature honeycomb type denitrification catalyst It is not suitable for the use of high ash conditions, and the plate type denitrification catalyst has excellent anti blocking, abrasion resistance and so on. It can run smoothly under high ash conditions. The preparation process of the plate type denitrification catalyst is monopolized by Japan, Europe and the United States. Although in recent years, the domestic research institutes are committed to the plate type catalyst molding. The research of technology and formula, but there is no independent intellectual property right now, which can be used in the production line of plate denitrification catalyst for industrial production. Therefore, it is of great significance to study the molding process and formula of plate type denitrification catalyst. This topic is made of roll pressing to prepare the plate type denitrification catalyst and the molding efficiency of the roller press molding method is high. In the pressing machine of the hydraulic press.
In recent years, our country has focused on solving the problem of air pollution control and increased the sulfur and nitrate emission standards of flue gas again and again. Therefore, the demand and quality of SCR denitrification catalyst are getting higher and higher. The carrier material TiO2 of the catalyst is more than 80% of the total catalyst content, and the domestic catalyst carrier material is mixed with fish and dragon, so the carrier material is needled. In view of this, three kinds of homemade carrier materials, HTm, PB1m, PB2m, were selected to prepare HT, PB1, PB2 series catalyst slurry by semi impregnation, and then the slurry was sealed by 24 hours and formed by the self designed plate forming machine. Finally, the forming catalyst was formed. The performance of the prepared plate type denitrification catalyst was tested under simulated flue gas for 5 days after heating at room temperature of -60 and 60-610 C for 33 hours. The performance of BET, Raman, XPS and TPR was used to detect the properties of the common TiO2-WO3-SO42- carrier materials in China and the denitrification of the catalyst prepared. The effect of efficiency provides a theoretical basis for evaluating the quality of domestic catalyst carrier materials. The interaction relationship between WOx and VOx and the modification mechanism of WOx to VOx are analyzed and discussed. The following conclusions are drawn:
The results show that the self designed roller type plate forming machine can successfully prepare the plate type catalyst without cracking. When the specific surface area of the carrier is too large, it is beneficial to reduce the degree of polymerization of VOx, but at the same time it promotes the formation of isolated VOx, and the surface area is too low, so the catalyst has a lower specific surface area. Therefore, the catalyst has a lower specific surface area. Only when the specific surface area of the carrier is suitable, it is most beneficial to the denitrification reaction, and the strong B acid site is easier to adsorb NH3, but the electron force between the strong B acid position and the NH3 is stronger, which causes the intermediate product not to decompose easily, and hinders the smooth progress of the reaction; the electronic effect between W6+ and VOx is far greater than that of W5+, the higher the content of W6+, the more advantageous to lift. The modification of high WOx to VOx, W6+Ox with oxygen defect structure form, is easier to combine with O and form W-O-V structure with VOx. Therefore, the W6+Ox of this structure is easier to have electronic action with VOx, which is beneficial to WOx to VOx. The lower the degree of polymerization of the carrier surface, the better the dispersion, the more beneficial to the contact between WOx and the VOx. The modification of VOx can promote the denitrification reaction, and the moderate reduction of the oxidation state of V in the oxidation position V5+=O can effectively inhibit the oxidation of NH3 and SO2; there is a interaction between WOx and VOx, and both are not isolated on the surface of the carrier. On the one hand, WOx can promote the polymerization of VOx topography through the occupying effect on the surface of the catalyst. On the other hand, WOx can interact with VOx to form W-O-V structure, reduce the oxidation of V5+=O and inhibit the formation of VOx.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TQ426

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