摘要
采用分子模拟法分别研究了MgZn-MOF-74和MgCu-MOF-74对CO_(2)/CH_(4)混合物吸附分离。首先使用Dmol3模块计算原子电荷和Forcite模块优化掺入不同比例金属离子的骨架结构;接着使用Sorption模块分别模拟吸附单组分CO_(2)和CO_(2)/CH_(4)混合体系的吸附等温线,然后计算混合体系的选择性系数;最后使用Forcite分析金属离子与气体分子的径向分布函数。通过模拟得到的吸附单组分CO_(2)的吸附等温线可以发现,压力小于200 kPa时Mg5Zn5-MOF-74的吸附能力最强,173 kPa时吸附量为6.3 mmol/g。压力大于1500 kPa时,Mg9Zn1-MOF-74的吸附量比其他MOFs高,最高达23.9 mmol/g,吸附量从大到小排序为:Mg9Zn1-MOF-74>Mg7Zn3-MOF-74>Mg5Zn5-MOF-74>Mg-MOF-74>Zn-MOF-74。对于Cu掺入的Mg-MOF-74,吸附量比原始的Mg-MOF-74要低。在CO_(2)/CH_(4)混合体系中,小于500 kPa的压力环境下,Mg5Zn5-MOF-74对CO_(2)的选择能力最强,选择系数最高可达到42。随着压力逐渐增大,选择系数逐渐下降直至被原始Mg-MOF-74超过。混入不同比例Cu的Mg-MOF-74的选择系数不理想。同时还通过径向分布函数图来分析CO_(2)和CH_(4)客气分子在MOF-74中的位置和客体分子与骨架之间的亲和力大小。
The adsorption and separation of CO_(2)/CH_(4) mixture by MgZn-MOF-74 and MgCu-MOF-74 were studied by molecular simulation.Firstly,the Dmol3 module is used to calculate the atomic charge and the Forcite module is used to optimize the skeleton structure with different ratios of metal ions.Then the sorption module was used to simulate the adsorption isotherms of single-component CO_(2) and CO_(2)/CH_(4) mixture system respectively,and then the selectivity coefficient of the mixture system was calculated.Finally,Forcite was used to analyze the radial distribution function of metal ions and gas molecules.By simulated the adsorption of the single group of CO_(2),the adsorption capacity of the Mg5Zn5-MOF-74 was less than 200 kPa while the adsorption capacity of the Mg5Zn5-MOF-74 was the strongest,and the adsorption amount was 6.3 mmol/g.When the pressure exceeded 1500 kPa,the amount of adsorption of the Mg9Zn1-MOF-74 was the largest,and the largest amount was 23.9 mmol/g.The amount of adsorption from large to small is Mg9Zn1-MOF-74>Mg7Zn3-MOF-74>Mg5Zn5-MOF-74>Mg-MOF-74>Zn-MOF-74.However,for Mg-MOF-74 incorporated with different proportions of Cu^(2+),the adsorption amount is lower than that of the original Mg-MOF-74.In the CO_(2)/CH_(4) hybrid system,Mg5Zn5-MOF-74 has the strongest ability to select CO_(2) under pressure environments of less than 500 kPa,with a maximum selection coefficient of 42.However,as the pressure gradually increased,the selectivity gradually decreased until it was surpassed by the original Mg-MOF-74.The selection coefficient of Mg-MOF-74 mixed with different proportions of Cu^(2+)is not ideal.At the same time,the position of CO_(2) and CH_(4) molecules in MOF-74 and the affinity between the gas molecule and the skeleton were also analyzed by the radial distribution function.
作者
梁友善
张冠华
陆威
LIANG You-shan;ZHANG Guan-hua;LU We(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China)
出处
《广州化学》
CAS
2023年第3期12-19,共8页
Guangzhou Chemistry
基金
国家自然科学基金项目(51976126)
上海市自然科学基金项目(22ZR144270)。
