【作者】 何川；

【导师】 钟秦；

【作者基本信息】 南京理工大学 ， 化学工程， 2010， 硕士

【摘要】 燃煤电厂烟气的NOx中95%以上是NO,若能将NO部分氧化成N02,然后湿法脱除；则有利于建设资源节约型社会,发展循环经济。第一步NO的催化氧化是关键。本课题实验研究了Mn-Cu/TiO2的制备及其低温催化氧化NO的性能,探讨了非均相NO氧化动力学,对催化氧化-化学吸收工艺过程进行了模拟研究。研究结果为新型NO氧化催化剂的工业化应用提供了依据。首先,结合BET、XRD、SEM、FT-IR等表征手段,在固定床多相催化反应装置上对一系列过渡金属氧化物催化剂M/TiO2(M=Mn、Co、Ce、Fe、Cu、Cr、Ni、Zn和Zr)催化氧化NO活性进行了测试,筛选出Mn-Cu/TiO2在低温有最好的活性。作为P型半导体的MnO、和CuOx接受电子速率快,表面吸附氧浓度较高;Cu2+可能取代晶格中的Mn2+,降低了费米能级,可促进P型半导体的导电,加快了反应物的吸附,加速催化氧化反应的进行。实验研究了各种制备方法及条件对Mn-Cu/TiO2活性的影响,结果显示在由溶胶-凝胶法制得的Ti02上负载总含量10%、Mn/Cu=2的锰铜双活性组分,浸渍、干燥后,300℃下焙烧得到的催化剂表现出最好的氧化NO效果。在300ppmNO、10%O2、空速41324h-1的模拟烟气条件下,220℃时NO转化率为50%,300℃时最高,为76.3%。较低的焙烧温度(300℃)有助于催化剂获得较大的比表面积(30.4m2/g)和孔体积(0.05mL/g),有利于催化剂活性的提高。其次,实验研究了各种工艺条件(温度、NO浓度、空速、02浓度、H20和S02的存在)对Mn-Cu/TiO2活性的影响,结果表明催化剂的活性曲线在150～300℃之间呈凸状,空速的降低、NO浓度的减小、O2浓度的增加均使NO的转化率显著提高。连续实验表明催化剂的稳定性良好。220℃时,催化剂基本不受H20的影响,有良好的抗水性能。温度的升高和水量的减少有助于减小H20对催化剂活性的影响。在空速较低且SO2浓度较大的条件下,该催化剂显示出一定的抗硫性能。再次,通过实验结合计算对Mn-Cu/TiO2作用下非均相NO氧化动力学进行了研究。结果表明：在300℃以下,O2浓度小于8%时,NO浓度对应的反应级数α为1.1061,02浓度对应的反应级数β为0.3972,活化能Ea为25757.05J/mol。外扩散阻力对反应的影响基本可以忽略,而内扩散阻力的影响不能忽略。最后,以200MW燃煤机组为对象,结合NO催化氧化和氨法吸收部分,利用ChemCAD软件模拟了同时脱硫脱硝工艺过程。结果为工业化开发提供了一定的参考。更多还原

【Abstract】 The coal-fired power plant over 95% of NOx is NO, if NO could be partialy oxidized to NO2, then removal by wet method; it will be beneficial for developing resources economic society and circulated economy.The first step:catalytic oxidation of NO is crucial.The preparation of Mn-Cu/TiO2 and its catalytic oxidation of NO ability at low temperature were studied.The heterogeneous kinetic of NO oxidation was discussed and the catalytic oxidation-chemical absorption process was also simulated. The results provide the evidences for the industrialization application of the new NO oxidation catalysts.Firstly, combined characterization methods of BET, XRD, SEM,FT-IR and TG/DTA, the catalytic activities of a series of transition metal oxide catalysts M/TiO2 (M=Mn, Co, Ce, Fe, Cu, Cr, Ni, Zn and Zr) were screened under the fixed bed heterogeneous catalysis reaction setup. The Mn-Cu/TiO2 shows the best catalytic activity at low temperature.As P type semiconductors, MnOx and CuOx receive electorns much faster, absorb more oxygen on the surface;Cu2+ may substitute of Mn2+ in the lattice, result in decreasing the Fermi energy level and promoting the electric ability of P type semiconductor, so the reactants were absorbed faster and the catalytic oxidation reaction will be accelerated eventually. The effects of different preparation methods and conditions on the catalytic activity over Mn-Cu/TiO2 were investigated.It showed that activity components with 10% total loadings, Mn/Cu=2, supported on the TiO2 which was prepared by sol-gel method, impregnated, evaporated and calcinated at 300℃,exhibited the best effect of NO oxidation. Under the simulated flue gas conditions:300ppmNO and 10%O2 at a GHSV of 41324h-1,the NO conversion reached 50% at 220℃,as well as the highest NO conversion of 76.3% was reached at 300℃.A larger surface area(30.4m2/g)and pore volume(0.05mL/g) could be obtained at a relative lower calcination temperature(300℃),and contribute to a higher catalytic activity.Then, the effects of several different operation conditions (temperatures, NO concentrations, GHSV, O2 concentrations, the existence of H2O and SO2) on the catalytic activity of Mn-Cu/TiO2 were studied.The results appear that activity curve raised between 150～300℃,the decrease of GHSV and NO concentration or the increase of O2 concetration will both make the NO conversion increased.The catalyst appeared stable during the continuous experiments.The catalyst was almost not affected at 220℃when H2O was introduced in the stream;And showed anti-sulfur ability under a lower GHSV when large amount of SO2 were introduced.Moreover, the heterogeneous kinetic of NO oxidation over Mn-Cu/TiO2 catalyst was studied by experiments and calculations.Under the conditions of temperatures below 300℃and O2 concentration below 8%,the results indicated that the reaction order with respect to NO was 1.1061,while the reaction order with respect to O2 was 0.3972 and the energy of activation determined was 25757.05 J/mol.The effect of outer diffuse can be ignore basicly, however the inner diffuse can not.Lastly,200MW coal-fired power plant was simulated as example, combined of the catalytic oxidation of NO and ammonia absorption part, the simultaneous desulfurization and denitrification process was simulated by ChemCAD software.The results provided the reference for the industrialization.application.更多还原