Monte Carlo模拟表面上吸附态物种的迁移对反应行为的影响

用MonteCarlo方法研究了非均相催化剂表面吸附态氢原子的迁移对催化反应活性的影响,模拟结果表明,吸附态氢原子扩散很慢时,表面活性位很快被氢原子饱和,转换频率TOF增大到一定程度时很快下降;而当表面吸附态氢原子的扩散速率达到足够大的程度时,TOF将不再受氢原子扩散的影响.

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.