硫化氢气体在金属有机骨架中吸附机理的分子模拟研究

Molecular simulation study on adsorption mechanism of hydrogen sulfide in metal⁃organic frameworks

研究硫化氢(H_(2)S)气体在金属有机骨架(Metal Organic Frameworks, MOFs)材料中的吸附机理,对应用MOFs材料控制城市地下有限空间内的H_(2)S气体具有重要意义。以不同类型的MOFs材料作为研究对象,基于Materials Studio软件建立了MOFs-H_(2)S吸附体系,应用巨正则蒙特卡洛(Rand Canonical Monte Carlo, GCMC)方法及分子动力学(Molecular Dynamics, MD)理论研究了相互作用能、吸附热、金属位点、官能团等的影响,在分子层面讨论了H_(2)S气体在MOFs中的吸附特性及机理。应用等温吸附试验验证了所使用分子模型及力场的可靠性。结果表明:不同金属位点对于吸附量有较大影响,对H_(2)S气体的吸附作用由强到弱依次为Mg^(2+)、Ni^(2+)、Co^(2+)、Mn^(2+)、Zn^(2+);亲水性官能团的引入利于H_(2)S气体的吸附捕捉;UiO-66-Cu因其团簇为网状结构更利于H_(2)S气体的捕捉与吸附。同时,该研究建立了吸附热方程,提供了MOFs吸附效果评判标准,为MOFs材料应用于城市地下有限空间吸附H_(2)S气体提供了理论依据。

MOFs material is a highly promising gas adsorbent.To find the factors that affect the adsorption of H_(2) S in MOFs,the effects of interaction energy,the heat of adsorption,metal sites,and functional groups were investigated by applying the Grand Canonical Monte Carlo(GCMC)method and Molecular Dynamics(MD)theory.This study focuses on the adsorption of H_(2) S by MOFs materials at ambient temperature and pressure.Different types of MOFs H_(2) S adsorption systems were established based on Materials Studio software.The adsorption properties and mechanism of H_(2) S gas in MOFs were discussed at the molecular level.The isothermal adsorption experiments were applied to verify the reliability of the used molecular models and force fields.MOF 303 is the most promising adsorbent in this research.The results show that the different metal sites have a great influence on the adsorption amount.For the adsorption of H_(2) S gas from strong to weak is Mg ^(2+),Ni ^(2+),Co ^(2+),Mn ^(2+),Zn ^(2+).We observed a jump in adsorption amount in the isothermal adsorption line of Mg MOF 74,which implies that it is more sensitive to pressure changes.UiO 66 Cu is obtained by modification of UiO 66,which is more favorable for the adsorption of H_(2) S gas because of its reticulated cluster structure.The adsorption capacity of H_(2) S is increased by 82%by the functional group modification method.In addition,the simulation results show that the introduction of hydrophilic functional groups is generally more effective.The established adsorption heat equation provides the criteria for judging the adsorption effect of MOFs and a theoretical basis for the application of MOFs materials for H_(2) S gas adsorption in urban underground confined spaces.The study of the adsorption mechanism of hydrogen sulfide(H_(2) S)gas in MOFs materials is important for the application of MOFs materials to control H_(2) S gas in the confined spaces of urban undergrounds.