【作者】 张秀艳；

【导师】 贾明君； 张文祥；

【作者基本信息】 吉林大学 ， 物理化学， 2010， 硕士

【摘要】 本论文采用湿法浸渍的方法合成金属氧化物负载型催化剂,结合X射线衍射、氮气吸附、红外漫反射、X射线光电子能谱等表征手段对材料的表面性质和结构进行了研究,并系统考察了这类金属氧化物负载型催化剂在苯甲醇氧化反应中的催化性能。采用湿法浸渍法以四种炭材料为载体制备了一系列炭负载型MnO_x催化剂,并用于以空气为氧源的苯甲醇液相氧化反应中。结果表明,10wt%MnO_x/NC-2催化剂具有较高的反应活性,明显优于以其它三种炭材料为载体制备的催化剂。并考察了负载量、焙烧温度、反应条件等参数对催化剂性能的影响。结合各种表征结果,可以认为催化剂表面存在的大量高分散、且易于还原的锰物种是反应活性提高的主要原因。以介孔炭(NC-2)为载体采用浸渍法和沉淀法制备了一系列负载型FeO_x催化剂,经过氩气条件下高温焙烧之后,应用于以空气为氧源的苯甲醇液相氧化反应中。考察了负载量、焙烧温度、反应条件等参数对催化剂的性能的影响。发现氧化铁负载量对催化剂活性影响很大,随着负载量的增加苯甲醇的转化率呈现逐渐增高的趋势,负载量为5wt%时活性最佳。还发现在673 K条件下焙烧制备的5wt%FeO_x/NC-2催化剂活性较高。中断试验未发现活性组分流失,循环试验催化活性有显著的降低。结合XRD、氮气吸附和H2-TPR等表征手段对催化剂的表面性质和结构进行了研究,认为催化剂中高分散氧化铁活性物种以及和载体NC-2之间的相互作用是催化活性高的一个重要原因。更多还原

【Abstract】 The selective oxidation of alcohols to the corresponding carbonyl compounds is one of the most essential transformations in the synthesis of fine chemicals, recently, The traditional non-catalytic methods of alcohol oxidation require stoichiometric oxidants such as dichromate and permanganate. However, these stoichiometric oxidants are ususlly hazardous and toxic. From the viewpoints of green chemistry, there is an urgent need to develop a catalytic oxidation process using oxygen or air as the oxidant in place of the stoichiometric metal oxidants. supported or confined monomeric or nano-sized Rd, Pt or Au based heterogeneous catalysts could efficiently catalyze the aerobic oxidation of alcohol. But Pd、Pt and Au are noble metals, limiting the practical application in the industrial production .Even more recent developments of highly active non-precious metal oxide, it is key to controlling the dispersion of metal oxide. But in the study of supported carbon materials, the pore structure and surface chemical nature is a hot spot of attention. This properties not only affect the adsorption of reactant molecules and proliferation, but also decided the dispersion of the active phase of species and their dispersion. Recenty, many carbon materials with novel structures have been developed, the CMK carbon materials prepared using mesoporous silica material as the hard template, block copolymer compounds as templates, prepared by self-assembly. The development of carbon materials offers new opportunities. Recently, Our team reported a new method for preparing nanoporous carbon, using sol-gel method, nanoporous carbon material (NC-2). The prepared carbon materials with uniform pore size distribution, many oxygen groups on the surface, showing a good potential application.We chose AC, CMK-3, CM-1C, and NC-2 four kinds of carbon materials as supports, A series of nanoporous carbonsupported MnOx materials prepared by conventional wet impregnation method, calcined under argon at high temperature , using in the liquid phase oxidation of benzyl alcohol with air as oxygen source. The influence of various factors, such as Mn loading, calcined temperature and reaction condition, on the catalytic performance was also investigated. It was found that 10wt%MnOx/NC catalyst exhibits relatively high activity (80.4% conversion of benzyl alcohol after 4 h reaction ), which is much higher than that of catalyst prepared by other carbon materials as supports. Combined with the characterization results, it could be proposed here that the relative high catalytic activity of MnOx/NC could be mainly assigned to the formation of highly dispersed and easily reduced MnOx species on the surface of NC-2 support.With respect to sustainable chemistry and following nature’s principles, iron is the ideal metal for environmentally benign catalyst generations in future because of availability, low toxicity, and price. We chose Fe2O3 as active species, A series of nanoporous carbon (NC-2) supported FeOx materials prepared by conventional wet impregnation method. Calcined under argon at high temperature , using in the liquid phase oxidation of benzyl alcohol with air as oxygen source. The influence of various factors, such as Mn loading, calcined temperature and reaction condition, on the catalytic performance was also investigated. It was found that the benzyl alcohol conversion increases with FeOx loading, it reaches a maximum at the FeOx content of 10wt%, It shows that the conversion of benzyl alcohol increased regularly with the higher loadings of the catalyst. But we chose 5wt% as the best. We also found that the 5wt% FeO_x/NC-2 calcined at 673 K exhibits the highest activity. No leaching of the active catalytic species occurred during the leaching test . But the catalytic activity decreased very much after reused for twices times. The catalysis were characterized by means of XRD, XPS and H2-TPR. We deemed that the carbon supported FeOx is a very well catalyst.更多还原