【作者】 赵宁；

【导师】 童华；

【作者基本信息】 北京化工大学 ， 环境科学与工程， 2014， 硕士

【摘要】 烟气脱硝工艺中,选择性催化氧化NO (SCO)并结合液相吸收脱硝工艺在近些年受到越来越多的关注,该工艺中NO氧化催化剂是制约其工业应用的关键,基于已有的研究成果,单一活性组分催化剂性能不能满足需求,因此本工作试图研究有效组分复配,制备铜铈钛基复合催化剂,可获得较高的催化氧化活性,并通过添加锰,以进一步提高催化剂催化氧化活性及低温催化氧化活性。催化剂制备采用等体积浸渍法,活性测试在固定床反应器中进行,本工作考察Cu/Ce摩尔配比,Mn元素的添加量,煅烧温度对催化剂氧化活性的影响,并且使用SEM、XRD、XPS等表征手段研究这些催化剂的表面结构,结晶程度及元素价态,最后研究了CuCeOx/TiO2和MnCuCeOx/TiO2催化剂的催化氧化NO动力学方程。研究发现当Cu/Ce摩尔比为1：2时组成的CuCeOx/TiO2催化剂催化氧化性能最好,但是CuCeOx/TiO2催化剂在较低反应温度下不具备很强的催化能力,因此实验将Mn元素添加到CuCeOx/TiO2催化剂组成MnCuCeOx/TiO2催化剂,MnCuCeOx/TiO2催化剂在较低反应温度下具备一定的催化氧化能力。煅烧温度对催化剂的影响显示,350℃煅烧得到的CuCeOx/TiO2催化剂催化氧化活性最好,而MnCuCeOx/TiO2催化剂在450℃下煅烧后活性最好。通过表征分析可知CuCeOx/TiO2催化剂在较高煅烧温度下,催化剂表面会出现严重的粘附与交联现象；对于较高温度下煅烧的MnCuCeOx/TiO2催化剂,其表面原本的层状结构发生改变,出现相互粘附与交联的现象。加入Mn元素后催化剂表面化学吸附氧含量提升明显。其中CuCeOx/TiO2-350催化剂在NO浓度500ppm,O2浓度10%,空速24000h-1,350℃条件下的氧化度为0.64。MnCuCeOx/TiO2-450催化剂在NO浓度50Oppm, O2浓度10%,空速24000h-1,250℃时的氧化度为0.55,300℃时的氧化度为0.76,350℃时受热力学平衡的影响,氧化度下降至0.69。对CuCeOx/TiO2和MnCuCeOx/TiO2催化剂进行动力学分析,得到两种催化剂反应活化能,发现CuCeOx/TiO2催化剂活化能高于MnCuCeOx/TiO2催化剂,由此可以判断MnCuCeOx/TiO2催化剂的催化活性好于CuCeOx/TiO2催化剂。更多还原

【Abstract】 Recently, Selective catalytic oxidation of NO (SCO) with the method of absorption by liquid attracts more and more attention in the flue gas denitration process. Catalysts for NO oxidation are the keys which could restrict their industrial application. The activity of catalysts with single active component could not reach the goal, which could be found in nowadays researches. Active components mixed with each others were researched in this work. Cu, Ce and Ti based catalyst was prepared and found that the activity for NO oxidation increased obviously by this catalyst. Mn was also added in this work, which could improve the catalytic oxidation activity of catalysts at low temperature.The method of equivalent-volume impregnation was used for the preparation of catalysts. Fixed-bed reactor was used for testing catalytic activity of catalysts, and analysed the influence of catalysts activity by the mole ratio of Cu/Ce and adding Mn. Experiment also investigated the influence of catalysts activity by the temperature of calcination. SEM, XRD and XPS were used for researching the surface structure of catalysts, the degree of crystallinity and valence state of element. The kinetics of NO catalytic oxidation reactions over CuCeOx/TiO2and MnCuCeOx/TiO2were researched in this work.The experiment found that the CuCeOx/TiO2catalyst with mole ratio of Cu:Ce=l:2perform the best catalytic activity than any other CuCeOx/TiO2catalysts. But this catalyst could not have a good activity at low temperature of reaction. So Mn was added into CuCeOx/TiO2catalyst, and the constituted MnCuCeOx/TiO2catalyst could perform a certain catalytic activity for NO oxidation.The experiment has studied on the effect of calcination temperature to catalysts and found that350℃and450℃are the best calcination temperature for CuCeOx/TiO2catalyst and MnCuCeOx/TiO2catalyst respectively. CuCeOx/TiO2catalysts under high calcination temperature with the serious phenomenon of adhesion and crosslinking could be found from the analysis of characterization. The surface with bedded structure changed into adhesion and crosslinking for MnCuCeOx/TiO2catalysts at high calcination temperature. Oxygen of activated absorption increased obviously for catalysts with Mn. When inlet concentration of NO was500ppm, O210%and space velocity24000h1, oxidation extent of NO over CuCeOx/TiO2reached0.64at350℃. The same condition of MnCuCeOx/TiO2, oxidation extent of over MnCuCeOx/TiO2reached0.55at250℃,0.76at300℃, and0.69at350℃for the effect of thermodynamic equilibrium.The kinetics of NO catalytic oxidation reactions over CuCeOx/TiO2and MnCuCeOx/TiO2were researched in this work, and gained the activation energy of these two reactions. It is found that the activation energy of CuCeOx/TiO2catalyst is higher than MnCuCeOx/TiO2catalyst, which could judge that the activity of MnCuCeOx/TiO2catalyst is better than CuCeOx/TiO2catalyst.更多还原