Poulet G, Tuel A, Sautet P
Laboratoire de Chimie, UMR 5182 CNRS, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France.
J Phys Chem B. 2005 Dec 8;109(48):22939-46. doi: 10.1021/jp050670x.
Water adsorption in the microporous aluminophosphate AlPO4-18 is studied by a combination of solid-state NMR, X-ray diffraction, and density functional theory calculations. The change of the framework structure upon hydration is moderate, and NMR gives local information on the environment of Al and P atoms. The structural distribution of water molecules in the channels has been explored by a combination of first-principle molecular dynamics simulations and of static geometry optimizations. Two starting points have been considered for the calculations. If the structure of the dehydrated aluminophosphate is used, the simulation result is not satisfactory with an incomplete hydration and no agreement with NMR results. Starting from a partial refinement of the aluminophosphate framework for the hydrated system, a structure with six tetrahedral and six octahedral Al atoms in the unit cell is obtained, involving twelve water molecules coordinated to Al atoms and twelve others in the channels, and in good agreement with experimental data.
通过固态核磁共振、X射线衍射和密度泛函理论计算相结合的方法，对微孔磷酸铝AlPO4 - 18中的水吸附进行了研究。水合作用下骨架结构的变化较为温和，核磁共振提供了铝和磷原子环境的局部信息。通过第一性原理分子动力学模拟和静态几何优化相结合的方法，探索了水分子在通道中的结构分布。计算考虑了两个起始点。如果使用脱水磷酸铝的结构，模拟结果不理想，水合不完全且与核磁共振结果不一致。从水合体系的磷酸铝骨架的部分细化开始，得到了一个晶胞中有六个四面体铝原子和六个八面体铝原子的结构，其中十二个水分子与铝原子配位，另外十二个在通道中，与实验数据吻合良好。
