无铬中变催化剂中铈的助催化作用及YBa₂Cu₃O_7-δ对甲苯的催化氧化

【作者】 马卓娜；

【导师】 郭益群；

【作者基本信息】 郑州大学 ， 物理化学， 2000， 硕士

【摘要】 本论文由两部分组成。 第一部分主要讨论了铈对无铬中变催化剂的影响。目前在CO变换反应中铁铬系催化剂一直是最常用的催化剂。但由于铬氧化物有剧毒而且价格昂贵，限制了它在工业上的应用，人们越来越注重能够替代铬的助剂的研究。通过XRD，TPR，SEM和GC等手段的研究，结果发现：水在含铈氧化铁样品表面的吸附符合焦姆金方程。铈的加入降低了水在样品表面的吸附热，从而使反应活性增加。在还原过程中，铈有细化颗粒的作用和表面富集现象，从而使初始还原温度降低而还原结束温度升高。 第二部分研究了以YBa₂Cu₃O_7-δ作催化剂对甲苯的催化燃烧。YBa₂Cu₃O_7-δ作为一种高温超导体，它不仅具有导电性和磁性，而且本身对氧化反应固有的催化特性，引起科研工作者的广泛兴趣。YBa₂Cu₃O_7-δ即可以用作轻度氧化催化剂，与碳氢化合物作用，产生用途广泛的工业品；而且能充当深度氧化的催化剂，有效地消除有机废气对环境的污染。在甲苯的氧化燃烧反应中，YBa₂Cu₃O_7-δ具有较高的催化活性和热稳定性，并且与贵金属催化剂相比，成本相当低。基于以上所提原因，YBa₂Cu₃O_7-δ是一种颇具发展前景的氧化催化剂。更多还原

【Abstract】 Abstract This dissertation consists two sections. The first section mainly dissusses about the effects of ceria in non梒hromia iron based CO high temperature shift catalyst. Currently, chromia iron based catalyst is still the most common in the water梘as shift reaction. But the poisonousness and the prohibitive material price of the chromia hold back the path leading to the industrial application. To solve the problems mentioned above, the research on the Fe~O.3桟eO~ catalyst was carried out. By XRD, TPR, SEM, XPS and GC, the experimental results show that the adsorption of water on the surface of ceria梒ontaining Fe203 catalyst obeys Temkin Equation. When the ceria is added in, the adsorption heat of water on the surface of catalyst decreases, therefore, the catalytic activity is improved greatly. It has also been found that ceria can refine Fe20.3 grains and is riched on the surface of catalyst in the process of reduction, which lead to a decrease of the initial reductive temperature and an increase of the final reductive temperature. In the second section, the catalytic activity of YBa2Cu3O-~ for toluene combustion has been investigated. YBa2Cu30-8, known as high桾e superconductor, has recently gathered great attention, not only due to its electric and megnetie characteristics but also due to its intrinsic catalytic activity for oxidation. YBa,Cu3O~ can 2 work as both mild and deep oxidation catalysts,whieh is used to produce a wide range of industrial chemicals from hydrocarbons and is becoming important in the cleaning of emissions from combustion of carbonaceous fuels. In the complete oxidation of toluene, Y YBa0Cu;30> ~ exhibits high catalytic activity and high thermal stability. Compared with nobel metal catalysts, YBa2Cu3O-8also has remarkable lower material cost. With the advantages mentioned above, YBa-,Cu30.-8 could become a more promising catalyst of oxidation.更多还原