The reaction mechanism of SiCl4 with H2 has been studied theoretically using Gaussian 98 program at B3LYP/6-311G^＊ level. Three different reaction paths （a, b, c） in the gas phase were obtained. The geometries, vib...The reaction mechanism of SiCl4 with H2 has been studied theoretically using Gaussian 98 program at B3LYP/6-311G^＊ level. Three different reaction paths （a, b, c） in the gas phase were obtained. The geometries, vibrational frequencies and energies of every stagnation point in the reaction channel were calculated and the mechanisms have been confirmed. The results show that path a has an activation energy of 79.12 kcal/mol, which was considered as the main reaction path. Comparably, paths b and c have the energy barriers of 125.07 and 136.25 kcal/mol, respectively. The reaction rate constant was calculated by TST method over a wide temperature range of 900～1600 K, which further confirmed that path a was the main reaction channel展开更多
文摘有机液体储氢技术作为一种新兴的氢能储运手段,因其在常温常压下具有高安全性、易于运输和重复利用的优势,有望成为实现氢能大规模、低成本、远距离输运的重要技术路径。本文基于密度泛函理论(Density Functional Theory,DFT)计算,研究了FeTi^(+)双金属阳离子催化甲基环己烷(Methylcyclohexane,MCH)脱氢反应的作用机理。计算中采用PBE0泛函,并引入DFT-D3色散校正,以提高计算精度。在双重态和六重态势能面上分别确定了中间体和过渡态的几何构型,并计算了相应的能量变化。研究结果表明,FeTi^(+)催化MCH脱氢反应在2种自旋态下呈现出不同的反应路径和能量特征:在双重态路径中,第2个氢分子的脱除为反应的决速步骤,反应整体呈放热特征(−1.77 kcal/mol);而在六重态路径中,最后1个氢分子的脱除为决速步,整体反应略微吸热(+0.16 kcal/mol)。此外,借助波函数分析方法,对反应中涉及的化合物开展了态密度(Density of States,DOS)与自然电荷(Natural Population Analysis,NPA)分析,结合轨道贡献与电荷转移分析,揭示了反应的内在机理。本研究为理解过渡金属双原子催化剂在有机液体储氢体系中的作用机理提供了理论依据,并为后续催化剂设计提供了一定的参考。
基金This work was supported by the Foundation of Education Committee of Liaoning Province (No.990321076)
文摘The reaction mechanism of SiCl4 with H2 has been studied theoretically using Gaussian 98 program at B3LYP/6-311G^＊ level. Three different reaction paths （a, b, c） in the gas phase were obtained. The geometries, vibrational frequencies and energies of every stagnation point in the reaction channel were calculated and the mechanisms have been confirmed. The results show that path a has an activation energy of 79.12 kcal/mol, which was considered as the main reaction path. Comparably, paths b and c have the energy barriers of 125.07 and 136.25 kcal/mol, respectively. The reaction rate constant was calculated by TST method over a wide temperature range of 900～1600 K, which further confirmed that path a was the main reaction channel
