分子筛限域孔道中吡啶的吸附结构和能量

摘要

以吸附于ZSM-5孔道中的吡啶分子为例,利用量子化学理论方法考察了计算模型和密度泛函方法的选择对吡啶吸附结构和吸附能的影响,从而为准确计算分子筛限域孔道中客体分子吸附态结构和能量参数提供了依据.计算结果表明,吡啶吸附能随着所选用的分子筛的计算模型(从8T到128T)增大而增大,当选用的孔道结构能够将整个分子筛的孔道结构完全包括进来的时候(72T)达到收敛.与常规的密度泛函方法(B3LYP和M06-2X)相比较,考虑到色散作用校正的B97D泛函方法能够很好地处理分子筛体系中主客体间的长程相互作用和弱相互作用,计算得到的能量数据与实验结果符合得很好.%The performance of different exchange-correlation functional for the description of the interaction of pyridine with different cluster models of ZSM-5 zeolite has been assessed. Theoretical calculations show that upon increasing the cluster model from 8T to 128T, the adsorption energy of pyridine in ZSM-5 zeolite increases gradually and reaches convergence by the 72T cluster model. On the basis of the 72T cluster model, the pyridine adsorption energy calculated with different functional is further examined. Compared to the conventional functionals (B3LYP and M06-2X), the B97D functional which takes into account the dispersion correction provides calculated results that agree well with experimental data. The present results indicate that the B97D functional is suitable for studying long-range interactions in weakly interacting systems.