用修正的简化局部密度理论模拟超临界流体系统的吸附特性

Adsorption properties simulation for supercritical fluid systems using revised simplified local density theory

清洁能源储存和超临界流体萃取工艺中经常涉及到超临界流体(supercritical fluid,SCF)的吸附现象,然而其理论模型研究并不广泛.局部密度简化(simplified local density,SLD)理论作为工程简化模型,已经成功应用于SCF在活性炭上的吸附.在此介绍了不同学者对SLD模型的状态方程、吸附相体积等方面的改进和发展.SLD模型关联高压过剩吸附量的数据误差较大,已有的研究主要是对状态方程修正.文章采用SLD-ESD方程,通过增加可调参数对吸附相体积修正,计算5种气体在活性炭上的高压吸附数据,结果表明模型能够应用在较宽的压力范围.使用LJ12-6势能模型替代10-4势能模型,关联拟合了超临界流体在活性炭和硅胶上的吸附数据,扩展了SLD理论的应用范围.

Supercritical fluid（SCF） adsorption occurs in clean energy storage and supercritical fluid extraction process,but lacks theoretical model.A simple model for engineering,simplified local density（SLD）,has been used for SCF adsorption on active carbon successfully.This paper introduces the research and development of SLD model involved equation of state and adsorbed phase volume.SLD model makes error when fitting high pressure excess adsorption,while previous researches mainly focused on the density of adsorbed phase to improve equation of states.This study used SLD-ESD equation to fit the adsorbed phase volume by adding adjustable parameters,and then calculated the five gases＇ data of pressurized adsorption on active carbon by fitting excess adsorption isotherm.The results indicate that equation can fit data exactly,including high pressure.Using LJ12-6 potential model to displace 10-4 potential model,new SLD equation can be used in the supercritical fluid adsorption on active carbon and silica gel,and extends the field of SLD theory.