文献类型：会议论文

英文题名：Density functional theoretical study on dehydration process of MgCl₂?6H₂O

作者：Liu, GS; Song, XF; Yu, JG

机构：[1]Jiangxi Sci & Technol Normal Univ, Dept Chem, Nanchang 330013, Jiangxi Provinc, Peoples R China;[2]E China Univ Sci & Technol, LRUE, Shanghai 200237, Peoples R China

会议论文集：International Conference on Magnesium - Science, Technology and Applications

会议日期：SEP 20-24, 2004

会议地点：Beijing, PEOPLES R CHINA

语种：英文

外文关键词：density functional theory (DFT); dehydration; MgCl2 center dot 6H(2)O; bischofite

摘要：Anhydrous magnesium chloride (MgCl2), the dehydration product from bischofite (MgCl2 center dot 6H(2)O) and as industrial raw material for preparation of electrolytic magnesium,. is now the most advanced and perfect technological process. For long, the detailed dehydration process was not known due to its dehydration complexity and lack of appropriate experimental conditions. In this paper, quantum chemistry method based on density functional theory (DFT) was used to study the whole dehydration processes. The molecular geometries Of MgCl2 center dot 6H(2)O, MgCl2 center dot 4H(2)O, MgCl2 center dot 2H(2)O, MgCl2 center dot H2O and MgCl2 were all optimized at level of B3LYP/6-31G*, the optimized geometrical parameters and correspondent energies corrected by the second order Moller-Plesset perturbation theory (MP2) were thus obtained. Results show that the energy variations corresponding to the whole dehydration steps from MgCl2 center dot 6H(2)O via intermediates MgCl2 center dot 4H(2)O, MgCl2 center dot 2H(2)O and MgCl2 center dot H2O, to anhydrous product MgCl2 are 35.55, 41.30, 28.55, 31.08kcal/mol, respectively. For steps of 2H(2)O removal, the energy variation from MgCl2 center dot 2H(2)O to MgC12 is 59.63kcal/mol, bigger than the steps from MgCl2 center dot 6H(2)O to MgCl2 center dot 4H(2)O (35.55kcal/mol) and from MgCl2 center dot 4H(2)O to MgCl2 center dot 2H(2)O (41.30kcal/mol), which means the last two water molecules are the most difficult to be removed. All these results are significant for mechanism study of bischofite dehydration and are helpful for industrial production of anhydrous magnesium chloride.