有机物在超临界CO_2中无限稀释扩散系数的分子动力学模拟

MOLECULAR DYNAMICS SIMULATION FOR INFINITE DILUTE DIFFUSION COEFFICIENTS OF ORGANIC COMPOUNDS IN SUPERCRITICAL CARBON DIOXIDE

根据物质的实验临界常数或与物质最基本分子结构相关的Joback或Lydersen临界常数估算法得到物质的临界常数,结合Lennard-Joned流体的对比状态方程,按照对应态原理得到了38种有机物分子的新的Lennard-Jones位能参数.由这些位能参数结合简单的组合规则,首次对一些高附加值的复杂实用有机物在313.15 K、16 MPa的超临界CO_2中的无限稀释扩散系数采用分子动力学模拟的方法进行了研究.模拟结果表明,采用这种新思路可以有效地预测超临界体系的扩散性质,满足超临界萃取工艺开发和设计的需要.

Lennard-Jones potential parameters of thirty-eight organic compounds were evaluated by combining critical constants experimentally determined or estimated by Joback/Lydersen methods with the reduced equation of state of Lennard-Jones fluid according to corresponding state principle. Molecular dynamics simulations of solute infinite dilute diffusion coefficients of practical organic compounds in supercritical carbon dioxide (313.15 K, 16 MPa) were then performed by using the potential parameters and simple Lorentz-Berthelot combining rules. It was shown that the simulation results predicted by molecular dynamics simulation were accurate enough for preliminary process design.