【作者】 陆正阳；

【导师】 陈建孟； 姜理英；

【作者基本信息】 浙江工业大学 ， 环境工程， 2010， 硕士

【摘要】 我国的火电厂目前以燃煤为主，燃煤排放的NOX在大气中形成的酸雨及光化学烟雾对环境及人体造成严重的破坏，因而控制并消除烟气中的NOX成为一项迫切的要求。目前最具有应用价值的方法是氨选择性催化还原（SCR）技术。本论文目的就是寻求一种高效净化NO、具有强抗硫性并且使用寿命长的低温选择性催化还原催化剂，并对其性能和脱除机理进行系统的研究。本论文采用等体积浸渍法制备了V₂O₅/ACF选择性催化还原低温（SCR）催化剂。空白ACF先用浓硝酸进行氧化改性，然后以酸氧化改性ACF为载体，负载偏钒酸铵以及其他活性物质。对制备的催化剂进行活性测试，考察活性物质负载量、温度、反应物入口浓度、氨氮比例、氧气含量等因素对脱硝效率的影响，以及考察系统中引入500ppm SO₂后催化剂的抗硫性。实验表明：在保持NH3、NO体积比为1.1、体积组成为1000×10-6NO、1000×10-6NH3、5% O₂以及载气N₂，温度180℃，催化剂V₂O₅/ACF质量为1.0 g的条件下，7%V₂O₅ /ACF催化剂有最好的脱硝活性，脱硝率能达到52%且有强抗SO₂中毒能力，脱硝率仅从无SO₂时的52%下降到50%。为提高V₂O₅/ACF的脱硝率及提高催化剂的稳定性和使用寿命，在筛选出的较好催化剂7%V₂O₅/ACF的基础上进行催化剂掺杂。由于Mn具有低温高效脱硝性能但抗硫性能较差的特性，与抗硫性较强的7%V₂O₅/ACF催化剂进行组合制备低温催化剂。对制备的系列7%V-（x）Mn/ACF催化剂进行活性测试，及引入500ppmSO₂进行抗硫性能考察。结果表明：在反应条件保持NH₃、NO体积比为1.1、体积组成为1000×10-6 NO、1000×10-6 NH₃、5%O₂以及载气N2，温度180℃，催化剂7% V₂O₅-（x）Mn/ACF质量为1.0 g的条件下, 7%V-3%Mn/ACF具有最好的脱硝率，达到69.5%，且在有500ppm SO₂时脱硝率也能达到62%，表现出了较强的抗硫中毒性能，实现了低温高效强抗硫性催化剂的制备。另外，考虑到V₂O₅/ACF的稳定性及使用寿命不高，而稀土元素具有稳定性好的特性，对7%V₂O₅ /ACF催化剂进行稀土元素（铈和锆）掺杂。实验结论表明：7%V-5%Ce/ACF具有较好的催化脱硝稳定性。在0-600 min内脱硝率仅从开始稳定时的58%波动到略低的54%，比未掺杂Ce的7%V₂O₅/ACF（从52%波动到43%）更稳定。实现了低温高效稳定性强催化剂的制备。对各催化剂进行BET比表面积分析、热重分析（TG）、X射线衍射分析（XRD）、X射线光电子能谱分析（XPS）、扫描电镜分析（SEM）、傅立叶红外光谱（FT-IR）等实验，以综合掌握催化剂的物理特征和化学特性，可以为催化剂催化净化NO的数据结论提供实验支持以及验证活性测试的结论，同时也可以为催化剂的开发和改进以及脱硝反应的可能机理提供指引。更多还原

【Abstract】 Currently, the power plants of our country rely mainly on coalburning,which release NOX to the atmosphere. This kind of gas is themain precursor of forming acid rain and photochemical fog in theatmosphere, which will cause serious damage to the environment and thehuman’s health. Therefore, it is urgent request to control the dischargeamount of NOX in the flue gas. One of the technologies that can effectivelycontrol the emissions of nitrogen oxides from these kinds of sources isselective catalytic reduction （SCR） of NOx with NH3. The purpose of thisstudy was to seek high-efficiency deNOx catalysts in low temperature,which also have sulfur resistance and long service life, and then toexamine the characterization and mechanisms of catalyst for NO reductionat low temperature.In this study, the catalysts were prepared by a solution-impregnationmethod. Activated carbon fiber （ACF） was modified with concentratednitric acid, and then loaded ammonium metavanadate and other activesubstances with HNO3-modified ACF as the carrier. The SCR performanceof V2O5/ACF catalyst was evaluated under varying reaction parameters, such as V₂O₅ loading, the reaction temperature, the volume ratio of NH3and NO, O₂ concentration and an introduction of 500ppm SO₂ intoinspection system. Results showed that the de-NO efficiency could beimproved greatly by ACF oxidized by 20% nitric acid and loaded by V₂O₅ .The catalyst of V₂O₅/ACF had higher de-NO efficiency when theconcentration ratio of NH3 and NO was 1.1, NO concentration was1000×10-6, O₂ concentration was 5%, and the reaction temperature was180℃. It also had a better SO₂ anti-poisoning ability, and the de-NOefficiency was only decreased from 52% to 50% when SO₂ introduced.In order to improve the de-NO efficiency and the catalyst stability ofV₂O₅/ACF, some other elements were introduced into the above catalyst（7% V₂O₅ /ACF）. Owing to manganese catalyst has a high denitrificationperformance at low-temperature but poor sulfur resistance, the lowtemperaturecatalyst can be prepared with 7%V₂O₅/ACF catalystssupported Mn. The results showed that the high activity with 69.5% of de-NO efficiency could be obtained under the condition that the volume ratioof NH3 and was 1.1, the flue gas was mixed with 1000×10-6 NO, 1000×10-6NH3, 5% O₂ as well as the carrier gas N2, the reaction temperature was180℃, and the mass of 7%V-Mn/ACF catalyst was 1.0g. When 500ppmSO₂ introduced, the de-NO efficiency still can reach 62%, which showinga relatively strong sulfur anti-poisoning ability. Furthermore, in order toimprove the stability and service life of V₂O₅ /ACF, the rare earth elements （Ce and Zr）, with a good stability characteristics, were doped into the 7%V2O5/ACF catalyst. Experimental results showed that 7%V-5% Ce/ACFcatalyst had better stability during denitrification process. The de-NOefficiency by 7%V-5%Ce/ACF was fluctuated from 58% to 54% whenreation time increased from 0 to 600min, which was better than thatdecresed from 52% to 43% by 7%V2O5/ACF.A series of experiments, such as BET surface area analysis, thermalgravimetric analysis （Thermal Gravity, TG）, X-ray diffraction analysis（XRD）, X-ray photoelectron spectroscopy （XPS）, scanning electronmicroscopy （SEM）, and Fourier transform infrared spectroscopy （FT-IR）were conducted to estimate the selected catalysts’physical and chemicalcharacters. The results not only supported the datas obtained from thecompared experiments, but also provided some theoretic base of thecatalyst improvement.更多还原