摘要
本文用Chemisorb 2800自动化学吸附仪和半经验的CNDO/2方法研究了H_2在二氯η-二聚吡咯合铂配合物(简称PDPP)上的吸附行为。通过实验绘制出H_2在PDPP上的吸附等温线。优化了该体系相对于能量的分子间距,计算了不同吸附态的结合能,分析了原子的电荷分布及吸附分子相对于配合物的不同吸附取向的影响。从理论上合理地解释了测定的结果。
Chemisorb 2800 automatic chemical adsorption apparatus and the CNDO/2 method have been employed to study the adsorption behavior of H2 on platinum dichloride-η-pbipyrrole complex (PDPP) . The determinations of the adsorption amounts show that the adsorption of H2 on PDPP can be described by Freundlich's adsorption isotherm equation and the adsorption amounts follow the order ( Vtot ) 50℃> ( Vtot ) 70℃> ( Vtot ) 35℃. Two kinds of chemisorption centres are observed, one strong and another weak.
Nine adsorption models of the adsorbate H2 relative to PDPP are chosen in the calculation. Different orientations of the adsorbed H2 have been considered. The intermolecular distances have been optimized with respect to the energy for each system. The CNDO/2 calculations on the bonding energies of adsorption complexes and atomic charges show that the adsorption of H2 on PDPP is carried out on two different active centres of adsorption, i. e. pyrrole ring and platinum ( II ). The calculation results suggest that stable complexes are formed only for the perpendicular orientation of H2 molecules ( see Fig. 1 , models (4), (7)). The energy minima occur at a distance of about 2.10 A with the binding energies of -13.637 and -24.525 kJ respectively. The results of theoretical calculations are in good agreement with the experimental determinations. The experimental results are discussed also.
出处
《分子催化》
EI
CAS
CSCD
1991年第1期66-72,共7页
Journal of Molecular Catalysis(China)
基金
国家自然科学基金
