负载型金属氧化物催化剂上甲苯和二氯甲烷的催化氧化性能

发布时间：2018-02-25 16:15

  本文关键词： 催化氧化 甲苯 二氯甲烷 金属氧化物 泡沫镍　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：环境问题已成为当今社会的焦点问题,治理空气污染刻不容缓。挥发性有机物(VOCs)被认为是造成空气污染日益严重的主要原因。这类化合物不仅导致光化学烟雾的产生,更对人身健康有深刻的影响,治理消除空气中的VOCs十分必要。目前应用较广的VOCs处理方法主要有吸附法和催化氧化法。吸附法较催化氧化法来说虽然更易执行,但却面临着竞争吸附、吸附时间短以致不能完全吸附,还有吸附剂再生困难等问题。相比之下,采取催化氧化的方法对VOCs进行处理,是更为彻底有效的方法。多种类型负载型贵金属及金属氧化物催化剂对VOCs氧化反应表现出良好的催化性能。当前,研究开发性能更加优异、且廉价易得VOCs氧化催化剂备受关注。本论文主要采用不同方法制备了一些负载型过渡金属氧化物催化剂,通过氮气吸附脱附(BET)、X射线粉末衍射(XRD)、扫描电镜(SEM)、程序升温还原(TPR)、程序升温脱附(NH3-TPD)等手段对催化剂材料进行表征,并评价了其对两类代表性VOCs化合物甲苯和二氯甲烷的催化氧化性能。论文的主要研究内容和结果如下:以Al_2O_3为载体,采用湿法浸渍和沉积沉淀法制备了一系列负载型金属氧化物催化剂。催化反应评价结果表明:与对应的只负载单一金属氧化物组分的催化剂相比,负载二元金属氧化物的催化剂对甲苯及二氯甲烷的完全氧化反应表现出更高的催化活性。H2-TPR等表征结果证实:添加第二组分能够影响催化剂的还原性能,提高活性组分在载体表面的分散性。由此可以认为,对于Al_2O_3负载的金属氧化物催化剂,通过采用适合的方法引入其它组分,能够有效调整催化剂的氧化还原性能,继而获得性能更加优异的VOCs氧化催化剂。以一种新型材料泡沫镍为载体,采用柠檬酸溶胶-凝胶路线制备了几种二元或三元过渡金属氧化物负载型催化剂。结果表明:以Cu:Mn:Ce为1:1:1的溶胶凝胶涂覆制备的泡沫镍负载型催化剂对甲苯完全氧化反应表现出较为优异的催化性能。其中,经500℃空气氛下焙烧制得的催化剂具有最佳的催化性能。在甲苯浓度为1000 ppm时,达到甲苯98%转化率的温度为260℃,明显优于其它类型催化剂。泡沫镍载体具有的独特的网状的三维结构、高的孔隙度和比表面积等特点,使其能够有效的负载和分散引入的活性组分,从而使这类催化剂表现出优异的催化性能。
[Abstract]:Environmental problems have become the focus of today's society, the control of air pollution is urgent. Volatile organic compounds (VOCs) are considered to be the main cause of the increasing air pollution. These compounds not only lead to the production of photochemical smog, It also has a profound impact on human health. It is necessary to remove VOCs from the air. At present, the most widely used methods for treating VOCs are adsorption and catalytic oxidation. Although the adsorption method is easier to implement than the catalytic oxidation method, However, it is faced with the problems of competitive adsorption, short adsorption time and difficulty in regeneration of adsorbent. In contrast, VOCs is treated by catalytic oxidation. Various types of supported noble metals and metal oxide catalysts show good catalytic performance for VOCs oxidation reaction. At present, the research and development performance is better. In this paper, some supported transition metal oxide catalysts were prepared by different methods. The catalyst materials were characterized by means of nitrogen adsorption and desorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), temperature programmed reduction (TPR), temperature programmed desorption (TPR), and temperature programmed desorption (TPD). The catalytic oxidation properties of toluene and dichloromethane, two kinds of representative VOCs compounds, were evaluated. The main research contents and results are as follows: using Al_2O_3 as the carrier, the catalytic oxidation of toluene and dichloromethane was studied. A series of supported metal oxide catalysts were prepared by wet impregnation and deposition. The catalyst supported on binary metal oxide showed higher catalytic activity for the complete oxidation of toluene and dichloromethane. The results showed that the addition of the second component could affect the reduction performance of the catalyst. The dispersion of active component on the surface of the support is improved. It can be concluded that the redox performance of the Al_2O_3 supported metal oxide catalyst can be adjusted effectively by introducing other components into the catalyst by appropriate method. Then VOCs oxidation catalyst with better performance was obtained. The catalyst was supported by nickel foam, a new material. Several binary or ternary transition metal oxide supported catalysts were prepared by citric acid sol-gel route. The results show that the foam nickel supported catalyst prepared by sol-gel coating with Cu:Mn:Ce = 1: 1: 1 is completely oxygen to toluene. The chemical reaction showed excellent catalytic performance. The catalyst calcined in air atmosphere at 500 鈩，

本文编号：1534232