岳晓宁.四氯化硅催化氢化合成三氯氢硅机理研究[J].分子催化编辑部,2013,(3):279-286
四氯化硅催化氢化合成三氯氢硅机理研究
First Principles Study on the Reaction Mechanism of Catalytic Hydrogenation Process of Silicon Tetrachloride
投稿时间:2013-03-05  修订日期:2013-05-02
DOI:
中文关键词:  四氯化硅,催化加氢,第一性原理,自由基,氯化钡
英文关键词:silicon tetrachloride, catalytic hydrogenation, the first principle, radical, barium chloride
基金项目:国家自然科学基金面上项目
作者单位E-mail
岳晓宁 四川大学化学工程学院 yorich@qq.com 
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中文摘要:
      针对四氯化硅催化氢化过程采用第一性原理对其机理对其进行模拟研究,结果表明:没有催化剂时,SiCl4与H2反应能垒为464.45 kJ/mol,反应能量为74.94 kJ/mol,与热力学计算结果71.85 kJ/mol一致。氯化钡可催化四氯化硅氢化反应,其最具催化活性表面为(111)面;H2在BaCl2(111)面上表现排斥性;SiCl4表现为吸附性,可在BaCl2(111)表面稳定吸附并生成?SiCl3自由基,过程吸附能为448.33 kJ/mol;在催化剂BaCl2存在条件下,SiCl4与H2反应为自由基反应,反应步骤能垒为400.23 kJ/mol;氢化过程能垒降为184.97 kJ/mol;催化氢化反应过程所需能量为64.20 kJ/mol。催化氢化过程反应条件相对无催化剂过程更为温和。
英文摘要:
      The treatment of silicon tetrachloride is the key problem for the development of polysilicon industries. Catalytic hydrogenation process is a promising alternative technology for current industrial process. However, the reaction mechanism of this process is not clear yet. In this research, hydrogenation process of silicon tetrachloride with and without catalyst was studied to determine the reaction mechanism with the first principle calculation. The calculation demonstrates that the thermo-hydrogenation without catalyst is a molecular reaction. The reaction energy of thermo-hydrogenation reaction of SiCl4 is 74.94 kJ/mol and the energy barrier is 464.45 kJ/mol, which is agreement with the results of thermo dynamic calculation. After employing barium chloride as catalyst, the hydrogenation process transfers into radical reactions. The best active crystal plane of BaCl2 is surface (111). Hydrogen molecular is repulsed by surface (111), meanwhile SiCl4 molecular can be adsorbed steadily to generate silicon trichloride free radical,?SiCl3, and adsorbed chloride. Then, the free radical ?SiCl3 reacts with H2 to produce trichlorosilane and free hydrogen atom. The latter combines with the adsorbed chloride atom to yield hydrochloride and desorb from surface (111). The adsorption energy of SiCl4 on the surface (111) is about -450 kJ/mol. The reaction energy of hydrogenation process of SiCl4 decreases to 184.97 kJ/mol and the energy barrier lowers to 400.23 kJ/mol. The employment of catalyst which betters and milders the reaction conditions significantly.
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