分形表面上CO氧化反应的蒙特卡罗模拟

众所周知，人们在理想完好的单晶表面上的动力学研究已取得了很大的成功[1]，然而对许多实际催化剂来说，传统催化理论和实验之间不符的情况仍然俯拾皆是．现在人们对造成这种情况的原因已经有了更加深入的认识：大量的实验事实表明，在表面催化反应体系中，不但催化剂表面具有复杂的分形结构，而且催化剂表面上的活性中心分布也具有复杂的分形特性[2]．“分形”是指那些具有分数维数的几何对象．这些对象往往是不规则的，不能用通常的欧氏几何来描述[3]．将分形引入催化科学中最早的是Pfeifer和Avnir等[4]人，至今已有近二十年的历史，现…

Monte Carlo Simulation of CO Oxidation Reaction on Fractal Surface

The CO oxidation reaction on DLA fractal surface has been studied in detail by Monte Carlo method. It was found that (1) when only adsorption and surface reaction were considered the O atoms and CO molecules on surface would self-organize after a reation period, which greatly decreased the touching chance among different reactant molecules and consequently decreased the reaction rate. Furthermore, O atoms tended to be adsorbed at the center or the inner area of DLA surface while CO molecules could exist only at the exterior; (2) the clusters of O atoms could be cut off by vacant active sites after the introduction of CO diffusion on surface, which would further give rise to accelerateion of the reacti0n rate; (3) when the reversible adsorption of CO was introduced O atoms and CO molecules could adsorb evenly on the whole DLA surface and then the reaction would be speeded up greatly, which suggested that for a good catalyst the adsorbing strength should be moderate.