改性二氧化钛负载贵金属Ru催化剂催化降解苯胺溶液（英文）

发布时间：2018-05-24 13:06

本文选题：催化湿法氧化 + 物理化学　；参考：《催化学报》2017年07期

【摘要】：苯胺类废水污染物具有结构复杂、浓度高、不易生物降解、生物毒性大等特点,传统的苯胺降解措施存在着许多弊端,很难达到排放标准.催化湿法氧化技术(CWAO)主要针对降解高浓度难降解的有机废水,表现出降解效率高、反应时间短、对生物毒性物质的废水降解效果良好等优点,越来越受到人们的重视.但催化剂在使用过程中,需要在高温高压下进行,且有机物降解产生了有机酸,使得催化剂的活性组分流失和载体的物理化学性质发生变化,导致其催化活性下降.因此,需要开发出一种降解活性高,性能稳定的催化剂成为此技术在工业中广泛应用的关键.本文采用溶胶凝胶法对二氧化钛进行改性,制备了Ti_(0.9)Zr_(0.1)O_2和Ti_(0.9)Ce_(0.1)O_2载体,采用过量浸渍法将三氯化钌负载到载体表面制备了2%Ru/Ti_(0.9)Zr_(0.1)O_2和2%Ru/Ti_(0.9)Ce_(0.1)O_2催化剂.在高温高压反应条件下,以苯胺为催化湿法氧化污染物,对不同催化剂湿法降解苯胺进行比较研究,系统地探究了催化降解的反应温度和反应压力对苯胺降解的影响.此外,利用HPLC-MS鉴定出催化降解产生的中间产物,确定了催化降解的反应路径图.在改性的催化剂中,2%Ru/Ti_(0.9)Zr_(0.1)O_2催化剂表现出最高的催化降解活性和稳定性.在初始苯胺浓度4 g/L,催化剂浓度4 g/L,反应温度180°C,O_2压力1.5 MPa下,反应时间5 h后,苯胺完全转化,COD转化率达88.3%.并且催化剂进行三次循环试验后,苯胺转化率仍接近100%.X射线衍射和N2物理吸附结果表明,Ce,Zr掺杂到TiO_2晶格中形成了共溶体,其晶格尺寸更小,比表面积和孔体积更大.负载贵金属后,并未出现其他晶相,说明贵金属均匀分散在载体表面.透射电镜结果表明,贵金属负载在改性TiO_2上表现出较好的分散性和较小的颗粒尺寸,为催化降解苯胺提供更多的催化活性位点,而Ru/TiO_2催化剂表面,贵金属发生团聚现象且颗粒尺寸大.X射线光电子能谱结果表明,Ce,Zr的掺杂使得TiO_2表面活性氧和四价Ru的含量增加,更多的表面活性氧成为催化降解苯胺的直接原因.H_2程序升温还原结果表明,在300-400oC处还原峰对应于催化剂载体晶格氧的还原,改性后,其还原峰增至2倍,即使在贫氧环境下,改性催化剂可以及时从载体中释放晶格氧,为催化降解苯胺提供更多的活性氧.
[Abstract]:Aniline wastewater pollutants are characterized by complex structure, high concentration, low biodegradation and high biotoxicity. There are many disadvantages in traditional aniline degradation measures and it is difficult to meet the discharge standard. Catalytic Wet Oxidation (CWAO) is mainly aimed at the degradation of high concentration organic wastewater which is difficult to degrade. CWAO has many advantages such as high degradation efficiency, short reaction time and good degradation effect on the wastewater of biotoxic substances, which has attracted more and more attention. However, the catalyst needs to be carried out at high temperature and high pressure, and organic compounds are degraded to produce organic acids, which results in the loss of the active components of the catalyst and the change of the physical and chemical properties of the support, which leads to the decrease of the catalytic activity. Therefore, it is necessary to develop a catalyst with high degradation activity and stable performance, which is the key to its wide application in industry. In this paper, TIO _ 2 was modified by sol-gel method to prepare Ti_(0.9)Zr_(0.1)O_2 and Ti_(0.9)Ce_(0.1)O_2 supports, and 2%Ru/Ti_(0.9)Zr_(0.1)O_2 and 2%Ru/Ti_(0.9)Ce_(0.1)O_2 catalysts were prepared by excessive impregnation of ruthenium trichloride onto the surface of the support. Under the conditions of high temperature and high pressure, aniline was used as the catalytic pollutant for wet oxidation. The effects of reaction temperature and pressure on the degradation of aniline were studied systematically. In addition, the intermediate product produced by catalytic degradation was identified by HPLC-MS and the reaction path diagram of catalytic degradation was determined. Among the modified catalysts, 2Rur / TiS _ (0.9) ZrS _ (0.1) O _ (2) catalyst showed the highest catalytic degradation activity and stability. When the initial concentration of aniline was 4 g / L, the catalyst concentration was 4 g / L, the reaction temperature was 180 掳C / L, the pressure was 1.5 MPa, and the reaction time was 5 h, the conversion rate of aniline was 88.3%. After three cycles, the conversion of aniline was still close to 100. X ray diffraction and N 2 physical adsorption. The results showed that cerium and zirconium doped into TiO_2 lattice formed eusolution, and the lattice size was smaller, the specific surface area and pore volume were larger. After loading the precious metal, no other crystalline phase appeared, indicating that the precious metal was uniformly dispersed on the surface of the carrier. The results of transmission electron microscopy showed that the noble metal supported on the modified TiO_2 exhibited better dispersion and smaller particle size, which provided more catalytic active sites for the catalytic degradation of aniline, while on the surface of the Ru/TiO_2 catalyst. The agglomeration of noble metals and the large particle size. X-ray photoelectron spectroscopy (XPS) results show that the doping of cerium Zr leads to the increase of active oxygen species and tetravalent Ru content on the surface of TiO_2. More surface active oxygen species become the direct cause of catalytic degradation of aniline. H-2 temperature programmed reduction results show that the reduction peak at 300-400oC corresponds to the reduction of lattice oxygen on the catalyst carrier, and after modification, the reduction peak increases to 2 times, even in oxygen-poor environment. The modified catalyst can release lattice oxygen from the support in time and provide more active oxygen for the catalytic degradation of aniline.
【作者单位】：华东理工大学化学与分子工程学院工业催化教育部重点实验室;
【基金】：supported by the National Natural Science Foundation of China(21333003,21577034) National Basic Research Program of China(2013CB933200) National High Technology Research and Development Program of China(2015AA034603) the Fundamental Research Funds for the Central Universities(WJ1514020)~~
【分类号】：O643.36;X703

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