吡啶与Rh(111)面相互作用的EHMO研究

吡啶作为加氢脱氮的模型化合物,与过渡金属Pt(111),Ni(100),Pd(110,111),Mo(110),Rh(111)面的吸附作用已有大量的实验研究,所采用的技术基本上是LEED,TDS,XPS,HREELS等,然而吡啶与Rh(111)面作用的理论研究尚未见报道.本文用EHMO法研究了吡啶与Rh(111)面的吸附作用,得到了最优吸附构型、结合能、集居数以及电荷分布和转移等,为新的脱氮催化剂开发提供了理论依据. 计算采用EHMO法,其中非对角矩阵元采用MWH近似:

EHMO STUDY ON THE INTERACTION OF PYRIDINE WITH Rh(111)

The adsorption of pyridine on the surface of Rh(lli)was studied by EHMO method. The adsorbed energy was calculated for C5H5N-Rh7 system with six different adsorption models, and then the best adsorption model was obtained. The results showed that the orientation of pyridine adsorbed on Rh(111) was perpendicular, and the pyridine molecule interacted with Rh(111) via the N and a-C atom, i. e. via the. interaction of a pair electrons of N,C1-N a-bonding and bon.ding of pyridine ring with of orbit of Rh(111). The calculated results showed that the electrons in adsorption system not only moved from pyridine ring to metal surface, but also feedbacked from d orbit of metal to pyridine ring. The a-hydrogen atom was easily lost and a C-N bonding was easily broken. In addition, the bonding energy obtained was 86.4 kJ/mol, indicating that it was a strong chemisorption.