Cu-Ce玻纤蜂窝催化剂的制备及其催化燃烧VOCs性能研究

发布时间：2018-03-26 21:36

  本文选题：铜铈氧化物　切入点：玻璃纤维　出处：《中北大学》2017年硕士论文

【摘要】：挥发性有机化合物作为一类主要的大气污染物,受到了广泛关注。催化燃烧因其效率高、能耗低,成为处理VOCs的有效方法之一。相比于贵金属催化剂,过渡金属催化剂成本低、稳定性好,具有很大的竞争力。本论文以玻纤蜂窝为载体,以CuO为活性组分,考察了活性组分负载量、煅烧温度、Cu/(Cu+Ce)摩尔比、络合剂对玻纤蜂窝催化剂催化燃烧VOCs活性的影响。通过BET、XRD、H2-TPR、NH3-TPD、VOCs-TPD等手段对催化剂进行表征,探讨了催化剂表面性质与催化剂活性之间的联系。首先采用等体积浸渍法,通过改变CuO担载量分别为8%、10%、12%,改变煅烧温度分别为500℃、600℃、700℃,制备了Cu/Al_2O_3-M玻纤整体式催化剂,通过对乙酸乙酯的催化燃烧实验考察了其催化性能。结果显示负载量为10%,煅烧温度为600℃的Cu10/Al_2O_3-M-600玻纤整体式催化剂催化活性最佳。采用共浸渍法通过改变Cu/(Cu+Ce)摩尔比分别为1、0.67、0.5、0.33、0.2、0,制备了一系列CuCe玻纤整体式催化剂,通过乙酸乙酯、异丙醇及甲苯的催化燃烧实验考察了催化活性。结果显示掺杂CeO2可以提高CuxCe1-x/Al_2O_3-M催化剂的催化活性,Cu_(0.5)Ce_(0.5)/Al_2O_3-M对异丙醇与乙酸乙酯催化活性最高,325℃时转化率即可达到100%。表征结果显示在CuxCe1-x/Al_2O_3-M玻纤催化剂中氧化铜以高分散态存在而氧化铈则是以小的纳米晶粒状态存在,而且纳米氧化铈颗粒尺寸随着Cu/(Cu+Ce)摩尔比的减小而增大。加入CeO2会降低活性氧的含量、减弱催化剂的还原性,同时提高催化剂表面总酸位的数量,特别是路易斯酸位的量,进而影响乙酸乙酯和异丙醇的吸附量。对活性最佳的Cu_(0.5)Ce_(0.5)/Al_2O_3-M玻纤整体式催化剂进行50h稳定性测试,结果显示,在325℃乙酸乙酯空速为20000h-1时,催化剂活性能保持97%以上。在性能最优的Cu_(0.5)Ce_(0.5)/Al_2O_3-M玻纤催化剂中添加酸性络合剂(苹果酸、柠檬酸、乳酸)和碱性络合剂(二乙烯三胺、三乙烯四胺、乌洛托品),考察络合剂对Cu_(0.5)Ce_(0.5)/Al_2O_3-M玻纤催化剂催化燃烧乙酸乙酯性能影响。结果显示,络合剂添加并没有提高催化剂活性。添加酸性络合剂增加了布朗酸位,但是对路易斯酸位并没有贡献,相应的也就没有增加乙酸乙酯化学吸附量;碱性络合剂加入,可以提高催化剂还原能力,但是降低了催化剂路易斯酸位以及总酸位的数量,降低了乙酸乙酯化学吸附量,共同作用导致催化剂活性减弱。Cux Ce1-x/Al_2O_3-M催化剂催化燃烧过程遵循Mars-van Krevelen规则,即催化活性由催化剂氧化还原能力与吸附能力共同影响。
[Abstract]:Volatile organic compounds (VOCs), as one of the major atmospheric pollutants, have attracted wide attention. Catalytic combustion has become one of the effective methods for VOCs treatment because of its high efficiency and low energy consumption. Compared with noble metal catalysts, transition metal catalysts have low cost. In this paper, glass fiber honeycomb was used as carrier and CuO as active component. The influence of the complexing agent on the catalytic combustion activity of glass fiber honeycomb catalyst was studied. The catalyst was characterized by BET-XRDX H2-TPRN NH3-TPD-VOCs-TPD, and the relationship between the surface properties of the catalyst and the activity of the catalyst was discussed. Firstly, the isovolumetric impregnation method was used to investigate the relationship between the surface properties of the catalyst and the activity of the catalyst. The Cu/Al_2O_3-M glass fiber monolithic catalyst was prepared by changing the loading capacity of CuO from 8 to 10 and calcining at 500 鈩，

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