单晶表面上水-气转移反应动力学及可逆吸附的作用—─Monte Carlo 模拟研究

The Kinetic Study of Water Gas Shift Reaction and the Role of Reversible Adsorption—Monte Carlo Simulation

用二元方格网络表示Ｃｕ（１１１）单晶表面上吸附活性位构型，建立了一个水－气转移反应的蒙特卡罗模型；对水－气转移反应的动力学进行了模拟，并研究了可逆吸附在表面反应中的重要作用．当水的解离吸附为反应的决速步骤时，模拟得到的ＣＯ和Ｈ２Ｏ的反应级数与Ｃａｍｐｂｅｌ等的单晶实验结果一致．模拟研究还表明，可逆吸附不仅可以抑制催化剂表面同种吸附物种ｃｌｕｓｔｅｒ的形成，而且可以不断提供新的吸附活性位，从而使表面反应稳定进行得以维持．

A Monte Carlo model for water gas shift reaction has been set up and the Cu(111) plane was represented by a two component active site square lattice. The kinetics of water gas shift reaction and the role of reversible adsorption of H 2O molecule were studied by Monte Carlo simulation. The modeled orders in CO and in H 2O are in good agreement with the experimental results obtained by Campbell et al. over Cu(111) single crystal surface when water dissociation is assumed to be the rate limiting step. In addition, the simulation shows that the reversible adsorption plays an important role in repressing the formation of cluster on the catalytic surface and in maintaining that the reaction progresses steadily.