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本文用原子簇模型(CM)的从头计算方法,计算了银表面甲醇氧化反应中的静态吸附物种的优化几何构型及吸附性质.计算表明在清洁银表面甲醇、甲醛只存在物理吸附;当表面存在吸附氧原子时,甲醇可在银表面形成两种分子态吸附;甲醛与表面羟基OH_(a)或氢原子H_(a)共存时在银表面能够形成化学吸附,且CH_2O_(a)极易与O_(a)反应生成深度氧化中间体η~2-甲二氧基;中间产物甲氧基在无氧的银表面能够形成稳定吸附,在富氧银表面极易进一步氧化脱氢生成产物甲醛.通过计算与实验结果的对照,我们对反应机理作了初步讨论.
In this paper, the ab initio method of atomic cluster model (CM) was used to calculate the optimized geometrical configuration and adsorption properties of static adsorbed species on the surface of methanol. The results showed that there was only physical adsorption of methanol and formaldehyde on silver surface, In the presence of oxygen atoms, methanol can form two molecular states on silver surface. Formaldehyde can form chemisorption on the surface of silver when it coexists with surface hydroxyl group OH_ (a) or hydrogen atom H_ (a), and CH_2O_ (a) The reaction of O_ (a) with O_ (a) resulted in the formation of a deep oxidation intermediate η ~ 2-methyldioxy. The methoxy group of the intermediate could form stable adsorption on the anaerobic silver surface and could be easily further oxidized and dehydrogenated on the surface of oxygen- Through the comparison between calculation and experimental results, we have discussed the reaction mechanism first.