Laboratory of Engineering Thermodynamics, Erwin-Schrödinger-straße 44, University of Kaiserslautern, 67663 Kaiserslautern, Germany.
Phys Chem Chem Phys. 2013 Oct 28;15(40):17374-82. doi: 10.1039/c3cp52910j.
We have measured experimental adsorption isotherms of water in zeolite LTA4A, and studied the regeneration process by performing subsequent adsorption cycles after degassing at different temperatures. We observed incomplete desorption at low temperatures, and cation rearrangement at successive adsorption cycles. We also developed a new molecular simulation force field able to reproduce experimental adsorption isotherms in the range of temperatures between 273 K and 374 K. Small deviations observed at high pressures are attributed to the change in the water dipole moment at high loadings. The force field correctly describes the preferential adsorption sites of water at different pressures. We tested the influence of the zeolite structure, framework flexibility, and cation mobility when considering adsorption and diffusion of water. Finally, we performed checks on force field transferability between different hydrophilic zeolite types, concluding that classical, non-polarizable water force fields are not transferable.
我们已经测量了水在 LTA4A 沸石中的实验吸附等温线，并通过在不同温度下脱气来进行后续吸附循环，研究了再生过程。我们观察到在低温下不完全解吸，以及在连续吸附循环中阳离子重排。我们还开发了一种新的分子模拟力场，能够在 273 K 至 374 K 的温度范围内再现实验吸附等温线。在高压下观察到的小偏差归因于高负荷下水偶极矩的变化。该力场正确描述了在不同压力下水的优先吸附位置。我们测试了沸石结构、骨架柔性和阳离子迁移率在考虑水吸附和扩散时的影响。最后，我们对不同亲水沸石类型之间的力场可转移性进行了检查，得出结论，经典的非极化水力场不可转移。
