O2和CO表面催化反应的活性位分布模型

对于O_2和CO表面催化反应，建立了一个新的不可逆Monte Carlo模拟模型。在 二维格子中，引进了表面活性位和非活性位的要领。模型假设，一定浓度的活性位 随机分布在非活性位上，形成了活性位分布的二维格子模型反应器，并在ZGB模型 的基础上，考虑了氧原子和CO分子的表面扩散，特别是引进了吸附粒子的定向表面 扩散。其中，活性位和活性位最近邻是表面吸附物质反应的活性中心，而非活性位 的作用是通过表面扩散传质。当活性位浓度C_a = 1且考虑扩散时，模型还原为增 加了扩散的ZGB模型。当活性位浓度C_a = 1且只考虑氧的扩散时，模拟结果表明， 扩散几率达到某一数值（0.3）时，二级相变点完全消失。当活性位浓度C_a逐渐减 小时，单位活性位产生的CO_2的速率不断增大，这表明活性位的利用率提高了。

Active Sites Distribution Model of Surface Catalytic Reaction of O_2 and CO

A new irreversible Monte Carlo simulation model, based upon the reaction of carbon monoxide and oxygen on a catalytic surface, is presented. Active sites and inactive sites are introduced on a two dimensional square lattice. Active sites of a certain concentration are distributed randomly over inactive sites, forming the model of two dimensional lattice of active sites distribution. Diffusion, especially directional diffusion, of the adsorbed particles is taken into account on the basis of ZGB model. Active sites and their nearest neighbor (nn) sites are assumed as reaction center and the role of inactive sites is to convey substances by diffusion for the reaction. The model reverts to the ZGB model, which includes surface diffusion when the concentration of active sites c a=1. In the case that c a=1 and only O diffusion is taken into account (when the probability of O diffusion reaches 0 3), the simulation results show that the second order phase transition disappears completely. The formation rate of each site of CO 2 increases continuously with the decreasing of the concentration of active sites ( c a), which shows that the efficiency of the active sites increased.