关键词: 丙烯, 歧化反应, 从头计算法, 氧化钼, 氧化钨, 表面吸附, 原子簇, 国家教委优秀年青教师基金

The adsorption of propene on the surface of MO3(M=Mo and W) is studied, in this paper, by use of a cluster model and the ab initio UHF geometry optimization method followed by the energy calculation with the second-order MΦller-Plesset perturbation procedure (MP2). The optimized geometries, the calculated net atomic charges and adsorption energies all show that the adsorption of propene on the surface of WO3 is stronger than that of MoO3. The electron charge is transferred from the π bonding orbital of the propene to the central atom M. When the propene is adsorbed on the surface of MO3 so that it is easier to break the carbon-carbon double bond and easier to take the metathesis reaction of propene The adsorption energies of propene on the surfaces of MoO3 and WO3 obtained from the MP2 calculations are 0.934eV and 0.506eV, respectively, and there is no energy barrier for the adsorption process, which leads us to understand qualitatively the experimental fact that the best reaction temperature (675K) of propene metathesis for using the WO3 catalyst supported on alumina is higher than that (480K) for using the MoO3 on alumina, and that the catalytic activity of the WO3 at 675K is higher than that of the MoO3 at 480K.

Key words: PROPENE, DISPROPORTIONATION REACTION, AB INITIO CALCULATION, MOLYBDENUM OXIDE, TUNGSTEN OXIDE, SURFACES ADSORPTION