超临界CO_2在有机液体中的分散

Dispersion of Supercritical CO_2 in Organic Liquid

针对近临界、超临界CO2如何使有机液体及石油体积膨胀、与有机液体及石油混相和如何萃取等问题,从分子结构和分子间作用力层面简要介绍了CO2在有机液体中的分散。近期研究结果表明,在(CO2+有机液体)体系中,近临界、超临界CO2并不是简单地溶解在有机液体中,而是形成了CO2-CO2分子聚集体、有机液体-有机液体分子聚集体和CO2-有机液体分子聚集体共存的分散体系。随着压力的增加,由于这些分子聚集体的聚集度、尺寸或聚集体之间距离(空间)的增加,导致有机液体宏观体积增加,并进一步发展形成混相。在相同温度、压力下,有机液体的分子越小,分子间作用力越弱,CO2越易于分散在其中,且溶解度更大,体积膨胀更明显,也更易于混相。同理,CO2更易于萃取相对分子质量较小的物质。对CO2与有机液体或石油混相机理和CO2对某些物质萃取原理提出了更科学的解释。

To investigate the mechanism o{ near-supercritical and supercritical CO2 making expansion of organic liquid and crude oil, being miscible with them, and extracting them, a brief summery about the dispersion of near-supercritical and supercritical CO2 in organic liquid based on microstructure of molecule and intermolecular forces was given. The research on the subject in recent years demonstrated that near-supercritical and supercritical CO2 were not dissolved in organic liquid only, but formed CO2-CO2 molecule aggregate, organic liquid-organic liquid molecule aggregate and CO2-organic liquid molecule aggregate in CO2 ＋organic liquid system. Due to increase of the size and aggregate degree of these molecule aggregates and the distance or space between the aggregates as pressure increased, the volume of the organic liquid was expanded, and became miscible with CO2. When temperature and pressure were fixed, the smaller the organic liquid molecule, and the weaker the intermolecular force between the organic liquid molecules, the easier the CO2 molecule to be dispersed into the organic liquid. Therefore, the solubility of CO2 in the liquid was higher, and the liquid expensed more and was easier to be miscible with CO2. For the same reasons, the substance with smaller molecule was easier extracted by CO2. The scientific explanation was given to the miscible mechanism of CO2 with organic liquid or crude oil, and to the principle of CO2 extraction.