Study Of Simulation Calculation On Adsorption Of Usual Industrial Waste Gas Within SiO₂ Nanopore

Using the Sorption module of Materials Studio?MS?software,the molecular dynamics method is applied in this paper to simulate and thus explore the adsorption differences of seven usual industrial gases,CH₄,SO₂,CO₂,NO₂,HF,H₂S and CO,within SiO₂ materials with the different pores.One hand,one has been carried out to explore the adsorption differences of the studied gases in the single-state within the nano-SiO₂ with the different size by analyzing the effects of temperature and pore size factors,and so on.On the other hand,the changes in adsorption for the studied gases have been explored when the presence of some water molecules in the SiO₂ nanopores,as well the competitive adsorption between two types of gases,so as to study the mixed gases competitive adsorption differences in the considered pores when the water molecules exist.Here,the model of SiO₂ pore is constructed through the importing of the SiO₂-quartz crystal derived from MS software,and then a three-dimensional?3D?periodic configuration is completed by the supercell processing.Moreover,after the gained model of SiO₂ that has been deleted a number of atoms based on requirements of the different pores,its nano-hole was automatically hydrogenated to thus present the saturation state using Adjust Hydrogen,in which three inner diameters,such as 1,1.5,and 2 nm,were completed respectively.In order to make the constructed simulation systems more close to the real cases,the periodic boundary conditions were set at 10 nm×10 nm×5 nm.The molecular dynamics of the studied models have been carried out to obtain their equilibrium when the energy precision,force field,and ensemble were selected by FINE,COMPASS,and NVT,respectively.Through the mean square displacement?MSD?and radial distribution function?RDF?analysis of the corresponding equilibrium systems,the adsorption differences of seven types of gases in the SiO₂ material with the different pore diameters were explored.The findings:1.Among all considered gases,adsorption states of the CH₄ and CO gases within the SiO₂ nanopore are bound states,showing the strongest adsorption capacity.For the four adsorption systems with SO₂,HF,H₂S,and CO₂,the studied gas molecules are not only adsorbed on the pore wall of SiO₂?forming bound state?,but also appears a large number of the free-states.It is noted that the adsorption of NO₂ in the corresponding system shows a unilateral adsorption,which is different from the adsorption distribution of other researched systems.2.Temperature and pore size have great effects on the gas adsorption,especially NO₂ adsorption has varied side adsorption phenomena at the different temperatures,in which the adsorption region is not fixed regularly.For CH₄ system,the adsorption capacity of the gas decreases with the increasing of pore size,whereas the capacity increases for SO₂ system.3.The distribution of the adsorbed gas appears to some characteristic changes when the presence of water molecules.For example,for CH₄ and CO adsorption system,there is no bound state for adsorption of the gas molecules in the SiO₂ pore and rarely free state,in contrast,a large number of water molecules were adsorbed by bound state inside the hole wall,as well free state adsorption,which speculated that formation of hydrogen bonds between water molecules and hydroxyl in the hole.4.In the selected SiO₂ with 1 nm pore size,there are great adsorption differences between the two competitive gases and the single-component cases,such as no obvious unilateral adsorption phenomenon was found in both SO₂/NO₂ and NO₂/CO systems when comparing case of NO₂ single component.