The Theoretical Reserch Of Adsorption Behavior About Acid Dioxide Gas In Cu-BTC

Cu-BTC is a kind of periodic framework meterials which composed of the framework unit of dimeric copper,1,3,5-benzene tricarboxylatle. This paper used monte carlo methed to stimulate adsorption amount,sites and energy distribution of three kind of diaoxide gas at room temperture in Cu-BTC with the gas fugacity increase. And finally use the density functional theory to explain the adsorption mechanism of different sites of gas molecule which exists in Cu-BTC’s framework unite,the research shows the results as follows:for pure component SO₂ is preferentially absorbed of the three kinds of gas, and can occupy the high activity sites,this can make SO₂ have higher adsorption energy.In adsorption sites of view, CO₂’s adsorption sites mainly centralized at tetrahedral pore canal,and have the existing of tendency of dissipation towards the main pore canal,according to the adsorption energy distribution,CO₂ have obvious advantage of two kinds of adsorption sites kurtosis（tetrahedral pore canal kurtosis and main pore canal kurtosis）, among which the tetrahedral pore canal kurtosis is more obvious.The adsorption amount of NO₂ is always lower,It dissociate on the surface of Cu-BTC.For competitive adsorption（SO₂:CO₂:NO₂=1:1:1）, SO₂ have preferable intermolecular force.Thus other gas molecular have less advantage of adsorption.Thus they are extruded out of the pore canal. According to this three adsorption energy distribution,it also shows that,because of high activity the SO₂ is,CO₂ no longer have the advantages of the two kinds of kurtosis.During the process of adsorption of this three kinds of gas moleculars.The main pore cannals and tetrahedral pore cannals corresponding to the framework unite of Cu-BTC.Because of the difference of angle,shows the difference of charge density.It shows that the tetrahedral pore canal with compact structure have higher van der waals force for gas moleculars.among this gas moleculars,SO₂ have the largest charge density contour distribution range and the highest adsorption energy.It shows that there are close combination between SO₂ molecular and Cu-BTC framework unite.Because of the highest advantage of adsorption for SO₂,among this three kinds of gas,SO₂ have the molecular sieving effect in Cu-BTC.The using of GCMC/DFT method can analysis effectively form many perspective for MOFs,which is expected to be a measure of type selection and modification for polymer complex structure.