化工学报2025，Vol.76Issue(5)：2313-2326,14.DOI:10.11949/0438-1157.20241314
双金属Co/Zn-ZIFs中C3H6和C3H8吸附和扩散行为分子模拟研究
Molecular simulation study on adsorption and diffusion of C3H6 and C3H8 on Co/Zn-ZIFs
摘要
Abstract
Based on first-principles calculations,11 bimetallic organic framework Co/Zn-ZIFs molecular models(1#,2#,3#,etc.)were constructed.Each model has the same window structure.The adsorption properties of C3 H6 and C3 H8 on Co/Zn-ZIFs were studied by the Grand Canonical Monte Carlo method.The adsorption mechanisms of C3 H6 and C3 H8 on Co/Zn-ZIFs were analyzed by adsorption heat distribution,adsorption sites,weak interactions,electrostatic potential and differential charge density.Molecular dynamics was used to calculate the diffusion characteristics of C3 H6 and C3 H8 at the windows of Co/Zn-ZIFs.The results indicated that the adsorption of C3 H6 and C3 H8 on Co/Zn-ZIFs mainly occurs near the imidazole ring and methyl group of the ligands.Within a certain range,increasing the temperature and decreasing the pressure were both beneficial for achieving preferential adsorption of C3 H8.At an ambient temperature of 323 K and a pressure of 0.5 bar,the ideal adsorption selectivity of C3 H8 to C3 H6 for 3#Co/Zn ZIFs is the highest,at 1.25.The diffusion free energy difference between C3 H6 and C3 H8 is the largest at the 6#Co/Zn-ZIFs windows,which is 14.60 kJ/mol.The self-diffusion coefficients of C3 H6 and C3 H8 are 3.910×10-10 and 1.445×10-12,respectively.The ideal diffusion selectivity of C3 H6/C3 H8 was the highest,as high as 270.59.For different Co/Zn-ZIFs molecular models with the same metal ratio have similar C3 H6 adsorption capacities and C3 H8 adsorption capacities.When the metal atoms with a small proportion are distributed alternately,the diffusion free energy of C3 H6 and C3 H8 is the highest,and the difference in diffusion free energy between C3 H8 and C3 H6 increases,thereby improving the separation selectivity of C3 H6/C3 H8.For Co/Zn-ZIFs molecular models with different metal ratios,they have similar C3 H6 adsorption capacities and C3 H8 adsorption capacities.As the Co/Zn ratio increases,the diffusion free energies of C3 H6 and C3 H8 molecules gradually increases,which increases the diffusion resistance of C3 H6 and C3 H8.These results provided valuable theoretical basis for analyzing the separation of C3 H6/C3 H8 mixtures by Co/Zn-ZIFs.关键词
分子模拟/Co/Zn-ZIFs/C3H6/C3H8/吸附/扩散Key words
molecular simulation/Co/Zn-ZIFs/C3 H6/C3 H8/adsorption/diffusion分类
化学化工引用本文复制引用
齐昊,王玉杰,李申辉,邹琦,刘轶群,赵之平..双金属Co/Zn-ZIFs中C3H6和C3H8吸附和扩散行为分子模拟研究[J].化工学报,2025,76(5):2313-2326,14.基金项目
中国石化科技项目(224117) （224117）
