新型光（电）催化材料的制备及其去除NOx的性能研究

发布时间：2018-09-07 12:53

【摘要】：随着中国的工业化程度的不断提高,近几年雾霾天气的长时间出现以及PM 2.5的爆表,大气污染已经引起了中国政府的高度重视。作为大气污染物之一的氮氧化物(NO_x),能够直接或间接地对环境和人类造成严重危害,由于氮氧化物的分解在低温时受到热力学限制,其反应速度十分缓慢,所以需要研发出有效的催化剂降低反应活化能,才能使反应顺利进行。光催化氧化技术去除氮氧化物具有反应条件温和、能耗低、二次污染少,且最终产物易于被植物、微生物等吸收的优点,因此被认为是去除NO_x的一种极具应用前景的环境友好型技术。但目前光催化氧化处理氮氧化物依然存在着光催化效率不高、光利用率不高、催化剂易失活等缺点,严重影响了光催化剂在实际中的应用。如今多数催化剂都是粉体催化剂,粉体催化剂会面临不易回收而且容易气体反应中吹走的情况,设计薄膜催化剂可以解决这个问题。将薄膜催化剂和电催化结合的话,利用电辅助光催化技术进一步提高氮氧化物去除效率,光催化和光电催化技术将在环境污染控制技术中具有广阔的应用前景。因此,主要的研究内容如下:1.氨基酸辅助合成介孔多层氧化锌微球及其光催化去除NO性能的研究采用醇热法利用氨基酸辅助合成了介孔多层氧化锌微球材料,通过调节釜热时间,随着时间增加,材料从实心到核壳到多层核壳再到空心的转变。考察了其利用紫外光去除NO_x的活性,多层结构的氧化锌具有最好的去除活性。多层结构的氧化锌不仅具有更大比表面积,增加反应活性位点而且可以对光进行多级反射,从而提高了光的利用率。2.Free-standing光电极薄膜的制备及其光电催化去除NO的研究利用微波高浓度碱溶液合成钛酸钠纳米线以及掺碳纳米管的复合材料,利用酸洗得到钛酸纳米线,管式炉氩气焙烧得到二氧化钛碳纳米管复合纳米线材料。在水溶液中超生分散后抽滤可以得到Free-standing薄膜材料,将其利用在光电催化氧化NO_x上,调变碳纳米管含量得到了最优活性的光电薄膜材料。解决了光催化与电催化结合以及回收困难等问题。3.不锈钢基底柔性光电极薄膜的制备及其光电催化去除NO的研究利用微波高浓度碱溶液合成钛酸钠纳米线以及掺碳纳米管的复合材料,利用酸洗得到钛酸纳米线,管式炉氩气焙烧得到二氧化钛碳纳米管复合纳米线材料。将在水溶液中超生分散后的二氧化钛碳纳米管复合纳米线材料抽滤到不锈钢网上后,不仅解决了材料的导电性问题,大大提高了导电性以及活性,而且材料弯折不裂开,柔韧性很好,稳定性很好。4.真空焙烧法制备大比表面积g-C_3N_4及其光催化去除NO的研究发展了一种利用真空法焙烧得到大比表面积材料的方法,这种焙烧方法不仅得到的材料在烧的过程中不会引入别的污染,而且还可以提高材料的比表面积。利用三聚氰胺以及三聚氰酸复合合成花球状白色前驱体,将其置于真空中焙烧得到大比表面积的g-C_3N_4材料,达到了182m2/g。将其与石墨烯复合得到GO-g-C_3N_4复合材料,将其抽滤在不锈钢网上,得到柔韧性很好的可见光光电催化薄膜材料,将在光电去除NO_x上,得到很好的去除效果。
[Abstract]:With the continuous improvement of industrialization in China, the long occurrence of haze weather and the explosion of PM 2.5 in recent years, air pollution has attracted great attention of the Chinese government. As one of the air pollutants, nitrogen oxides (NO_x), can cause serious harm to the environment and human directly or indirectly, because of the decomposition of nitrogen oxides. At low temperature, the reaction rate is very slow because of the thermodynamic restriction, so it is necessary to develop an effective catalyst to reduce the activation energy of the reaction, so that the reaction can proceed smoothly. However, there are still some shortcomings in photocatalytic oxidation of nitrogen oxides, such as low photocatalytic efficiency, low light utilization rate and easy deactivation of catalysts, which seriously affect the practical application of photocatalysts. Powder catalysts are difficult to recover and easy to be blown away in gas reactions. Thin film catalysts can be designed to solve this problem. If thin film catalysts are combined with electrocatalysis, Electro-assisted photocatalysis will be used to further improve the removal efficiency of nitrogen oxides. Photocatalysis and photocatalysis will be used to control environmental pollution. Therefore, the main research contents are as follows: 1. Amino acid-assisted synthesis of mesoporous multilayer zinc oxide microspheres and their photocatalytic properties for NO removal were studied. Mesoporous multilayer zinc oxide microspheres were synthesized by alcoholysis with amino acid-assisted method. With the increase of reaction time, the materials changed from solid to nucleus. The activity of removing NO_x from shell to multi-layer core-shell and then to hollow was investigated. The ZnO with multi-layer structure has the best removal activity. Preparation and photocatalytic removal of NO by ng photocathode films Free-standing thin films were prepared by photocatalytic oxidation of NO_x with carbon nanotubes. The problems of photocatalytic and electrocatalytic combination and recovery were solved. 3. Preparation of flexible thin films on stainless steel substrates and their photocatalytic removal of NO were studied. Sodium titanate nanowires and carbon nanotubes doped composite materials were synthesized by alkali solution with high concentration of water. Titanate nanowires were prepared by acid washing and then calcined in argon gas in tubular furnace. It not only solves the problem of conductivity, but also greatly improves the conductivity and activity of the material. The material has good flexibility and stability. 4. Preparation of large specific surface area g-C_3N_4 by vacuum roasting method and its photocatalytic removal of NO have developed a method of obtaining specific surface area material by vacuum roasting method. The composite of melamine and cyanuric acid was used to synthesize the white flower ball precursor, which was calcined in vacuum to obtain the g-C_3N_4 material with specific surface area of 182m2/g. The composite of melamine and graphene was prepared. GO-g-C_3N_4 composite material was filtered on stainless steel mesh to obtain visible light photocatalytic film material with good flexibility. It will get good removal effect on NO_x photoelectric removal.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X701;O643.36

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