FAU型沸石吸附CO_2的蒙特卡罗模拟研究

使用巨正则系综的蒙特卡罗(GCMC)方法计算了CO2在NaY沸石上的吸附等温线,通过拟合实验数据进行力场参数的优化。对NaY沸石吸附CO2的模拟结果进行分析发现:CO2在NaY沸石上的吸附首先发生在八面沸石超笼的孔口区域,当压力增加时,CO2分子向超笼中心方向扩散。SII是第一优先吸附位,其次是SIII位。随着吸附量的增加,SII位Na+与CO2之间的距离越来越短,但是在Na+离子附近CO2与Na+之间的作用均呈现近似直线的构型。基于优化力场参数计算了NaX沸石的CO2吸附等温线并与实验值进行比较,结果表明计算和实验值比较吻合,说明优化力场适合不同硅铝比的FAU型沸石。

Monte Carlo simulation of CO2 adsorption in FAU zeolites

Adsorption of CO2 in zeolite NaY was investigated with grand canonical Monte Carlo method(GCMC).The optimized force field parameters were obtained by adjusting force field parameters of Na+ in zeolite NaY and O in CO2 molecule to fit the experimental data.The results showed that CO2 adsorption firstly occurred in the pore entrances,and then diffused into the centre of the supercage when the pressure increased.Site SII was the preferred adsorption site,and site SIII was the second one.With the increase of adsorbed CO2,the distances between Na+ and CO2 became shorter,while the angles of CO2 molecules interacting with Na+ almost kept linear geometry.Adsorption data of CO2 on NaX zeolite was calculated using optimized force field and compared with experimental data.The good agreement between simulated and experimental data indicates that the optimized force field is suitable for FAU zeolites with different silicon aluminium ratios.