催化剂表面上分形杂质对CO氧化反应的影响  

Effects of fractal impurities in the catalytic surface on oxidation reaction of CO

作　　者：李洪[1] 钱昌吉[2] 吴一琦[1] 钟瑞[1] 

机构地区：[1]温州大学瓯江学院,浙江温州325035 [2]温州大学物理与电子信息学院,浙江温州325035

出　　处：《计算机与应用化学》2008年第5期635-640,共6页Computers and Applied Chemistry

基　　金：浙江省自然科学基金(Y607142)

摘　　要：担载型金属类催化剂表面,在分子层面上往往有些杂质,也许来自使用中的反应物料。这些结构性杂质会影响催化剂的结构与性能,于是本文引入杂质分形结构的概念,通过Monte Carlo模型去分析和探讨担载型金属催化剂表面CO的催化氧化反应行为。模拟结果发现,催化剂活性中心的不均匀分布,在分形杂质所包围的小区域,O_2在催化剂表面活性中心的吸附更加困难。特别是在杂质所占比例较大时,催化剂的活性点在空间被隔离开而形成许多孤立小岛,即使在CO分压较小时,催化剂表面的局部区域也会发生O和CO中毒。随着杂质比例的增加,导致催化剂表面的活性空位分布发生变化,大大减少了CO分子和O原子的接触机会,反应速率随之降低,催化剂活性中心的利用率也降低。Supported metal catalysts surface often have some impurities at the molecular level, which may be introduced by the reactant material during the process of catalysts. Based on such structural impurities affecting structures and properties of the catalyst, the fractal structure of impurities is presented, and the Monte Carlo model is introduced to analyze and study CO oxidation reaction on supported metal catalyst surface. Simulation results showed that active sites are distributed uneven on the catalyst surface, such as the small region surrounded by fractal impurities where O2 is adsorbed more difficult in the catalyst surface. Especially in larger proportion of impurities, active sites are isolated in space and they are formed many isolated islands, even in the small partial pressure of CO, both O poisoning and CO poisoning occurre on the local area of catalyst surface. With the increase of the impurities＇ proportion, the activity distribution of catalyst surface changes, the chance of contacts between CO molecules and O atoms reduces greatly, the reaction rate decreases, and the utilization ratio of active sites on catalyst surface lowers.

关 键 词：表面反应 催化剂 模拟 蒙特卡罗方法 分形 

分 类 号：O643[理学—物理化学]