论文部分内容阅读
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.
Aniline wastewater has the characteristics of complex structure, high concentration, not easily biodegradable, and high biological toxicity. The traditional aniline degradation methods have many disadvantages and are difficult to meet the emission standards.Catalytic wet oxidation (CWAO) The concentration of organic wastewater which is difficult to be degraded shows more and more demerits due to its advantages of high degradation efficiency, short reaction time and good biodegradation of waste water, but the catalyst needs to be used under high temperature and pressure , And organic matter is degraded to produce organic acid, which leads to the loss of the active component of the catalyst and the change of the physicochemical properties of the carrier, resulting in the decrease of the catalytic activity. Therefore, a catalyst with high degradation activity and stable performance needs to be developed. (0.9) Zr_ (0.1) O_2 and Ti_ (0.9) Ce_ (0.1) O_2 were prepared by the sol-gel method.The trichlorination Ru / Ti 0.9 Zr 0.1 O 2 and 2% Ru / Ti 0.9 Ce 0.1 O 2 catalysts supported on the surface of carrier were prepared.Under the condition of high temperature and high pressure, Wet oxidation of pollutants, different catalysts wet aniline degradation comparative study of the catalytic degradation of the reaction temperature and the impact of reaction pressure on the degradation of aniline.In addition, the use of HPLC-MS identified intermediate product of catalytic degradation , The reaction path of catalytic degradation was confirmed.At the same time, 2% Ru / Ti 0.9 Zr 0.1 O 2 catalyst showed the highest catalytic activity and stability.In the initial aniline concentration of 4 g / L , The catalyst concentration was 4 g / L, the reaction temperature was 180 ° C, the pressure of O 2 was 1.5 MPa and the reaction time was 5 h, the conversion of aniline reached 88.3% .After three cycles of catalyst, the aniline conversion was still close 100% .X-ray diffraction and N2 physical adsorption results show that, Ce, Zr doped into the TiO 2 lattice to form a co-melt, the smaller lattice size, larger surface area and pore volume.After loading the precious metal does not appear The other crystal phases indicate that the noble metal is uniformly dispersed on the surface of the support.The TEM results show that the noble metal loading shows better dispersion and smaller particle size on the modified TiO_2 and provides more catalytic active sites for the catalytic degradation of aniline , While Ru / TiO_2 X-ray photoelectron spectroscopy results show that the doping of Ce and Zr increases the content of surface active oxygen and tetravalent Ru of TiO_2, and more surface active oxygen becomes the catalyst for the degradation of aniline .H2 temperature-programmed reduction results show that the reduction peak at 300-400oC corresponds to the reduction of the lattice oxygen of the catalyst carrier. After the modification, the reduction peak is increased to 2 times. Even in the oxygen-lean environment, the modified catalyst The lattice oxygen can be released from the support in time, and more active oxygen can be provided for the catalytic degradation of aniline.