ADSORPTION STUDY OF WATER IN METALLIC ION CONTAINED MCM-41 BY MD SIMULATIONS

摘要

Molecular dynamics simulations were carried out to investigate the local average density distribution of some water molecules confined in mesoporous MCM-41 whose pore size was tailored to be 2.5nm. Pure-silica MCM-41 as well as those containing some metallic ions such as Al~(3+), Cu~(2+), and La~(3+) was simulated. The unit cells were modeled as planar slitlike pore formed with 3D structured walls. With the temperatures rising from 273K to 373K step by step, the local average density distributions of water molecules showed different performance in each kind of MCM-41. The Al-containing and La-containing MCM-41 performed better than the other two owing to their higher adsoiption amount and lower desorption temperature. On the other hand, the slight structural difference of the two sides of the walls leaded to the dissymmetry of density distribution in the neighborhoods of each wall. The increased polarity, the active sites introduced on the surface, the structure changes, and so on, may be the reasons for the improvement.