CO_2和H_2合成甲醇的量子化学模拟

Quantum chemical simulation on the reaction of methanol synthesis from CO_2 and H_2

利用分子模拟软件模拟CO2和H2合成甲醇的反应机理。首先,应用密度泛函理论(DFT)在B3LYP/6-311G++**水平上优化反应过程中各驻点(反应物、中间体、过渡态和产物)的几何构型,在优化基础上再计算频率来确定反应的过渡态;然后在CCSD/6-311G++**水平上计算各物种的单点能。结果显示:在两条反应通道中,生成中间体CO释放出的能量比生成甲酸的大,反应的最优途径是先生成HOCO自由基,继续加氢生成CO,然后再生成甲醛,最后生成甲醇。从构型参数看,模拟结果与文献值较接近,表明计算结果是可靠的。

The reaction mechanism of synthesis of methanol from CO2 and H2 was simulated by using the molecular simulation software.Density functional theory（DFT） was used to optimized the geometries of various stationary points,such as reactants,transition states,intermediates and products at B3LYP/6-311＋＋＊＊ level.Based on the optimized geometries,the frequencies of all species were calculated out to determine the transition states.The single energies of stationary points along the pathway were also calculated at CCSD/6-311G＋＋＊＊ level.The results showed that there were two pathways in the reaction,and the main reaction was as follow： CO2→CO→H2CO →CH3OH.As to the configuration of classic molecules,the calculated results were in good agreement with the values in literature,which indicated that the results should be reliable.