甲醇与金属离子相互作用的DFT研究

Interaction Between CH_3OH and Matel Ions:Theorital Studies

采用量子化学的DFT理论,在B3LYP水平上模拟了光催化H2O还原CO2的目标产物CH3OH与几种金属离子在基态时的相互作用,研究发现相对高价的金属离子在基态低配位数时会使甲醇分子离解,而高配位且电荷被大部分中和后则不会使其离解,中间价态的离子配位数达到4(含)以上则不会使其离解,低价离子不会使其离解。在实际的反应过程中,由于羟基和大量水分子的存在,金属离子几乎没有机会以高价态和低配位数与产率很低的甲醇接触,因而使其离解的几率极小,所以负载在TiO2上的金属离子不会影响目标产物甲醇的脱附。

The interaction between several kinds of metal ions loaded on TiO2 and the target product CH3OH in the photoreduction of CO2 with H2O has been calculated with DFT at B3LYP level.The results revealed that metal ions at the ground state and low coordinate number dissociated CH3OH by seized its hydroxyl radicals,while metal ions at hyper coordinate number and the most part of charge neutralized affected the geometry structure of CH3OH little.Low valence metal ions and intermediate valence metal ions which coordinate number is 4 or upwards have no much effect to CH3OH.In the practical reaction,there is almost no opportunity for hyper valence and low coordinate number metal ions to touch low yield CH3OH,therefore the probability for dissociation of CH3OH is minimal and metal ions loaded on TiO2 have no resistance to the desorption of CH3OH.