Monte Carlo simulation of diffusion of adsorption species on heterogeneous surface

Monte Carlo method was used to study the effect of diffusion of adsorbed hydrogen atoms on the methanol synthesis reaction behavior under a supercritical condition. The lattice model was employed to describe the surface processes, which included adsorption of reactants, surface reaction, surface diffusion of adsorbed species and re-adsorption of the product. The model converted Monte Carlo steps to the real time according to Botzzman equation. The results indicated that when the adsorbed hydrogen atoms diffused slowly, the active sites reached saturation and the turnover frequency (TOF) declined quickly, The magnitude of TOF was not influenced by the diffusion rate of adsorbed hydrogen atoms when it reached an enough high value.