چكيده به لاتين
Three types of carbon structures were designed in this study.Through GCMC simulations at 300K and 0.1-10 bar, we investigated the adsorption of pure CO2, CH4, and N2 and CO2/CH4 and CO2/N2 binary gas mixtures with 5/95 and 20/80 molar percentages, respectively. In the first type of designed structures, carbon nanotube bundles (CNTs) were used as carriers of four kinds of ionic liquids (ILs): methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][TF2N]), 1-Butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), methylimidazolium thiocyanate ([BMIM][SCN]) and methylimidazolium methyl sulfate ([BMIM][MeSO4]). The adsorption and separation of CO2 were investigated in this section using CNTs bundles with different types of anion and the number of pairs of ionic liquid molecules. There was an increase in separation as the number of ILs molecules in the composites increased. Also, thermodynamic quantities and isosteric heat of adsorption indicate a strong tendency for composites with ILs to adsorb CO2. In the second type of designed structures, pristine CNT and functionalized CNT (F-CNT) with -NH2 and -COOH functional groups were used as fillers in the cellulose acetate butyrate (CAB) structure. CNTs and F-CNTs provide selective CO2 adsorption between CH4 and N2, according to adsorption isotherms, selectivity, and isosteric heat calculations. Additionally, thermodynamic parameters and Henry's constant (KH) were calculated, showing that CH4 and N2 have lower KH than CO2 and have a weaker affinity for composite surfaces. The Gibbs free energy changes and surface potential of CO2 are higher than those of CH4 and N2, indicating that CO2 adsorption is more favorable and spontaneous on composites. Furthermore, the higher entropy change of CO2 adsorption indicates that CO2 molecules form a much more stable rearrangement than CH4 and N2. Ten carbon molecular sieves (CMS) with different densities were obtained in the third designed structure by pyrolyzing cellulose. The highest amount of CO2 adsorption was found in CMS, with a density of 0.351 g/cm3. CH4 and N2 had smaller Henry's constants than CO2, and their affinity for CMS surfaces was weaker than that of CO2. With increasing CMS density, CH4 and N2 adsorption decreased according to thermodynamic quantities. As CO2 has a higher Gibbs free energy and surface potential than CH4 and N2, its adsorption on CMSs is more favorable and spontaneous. According to the higher entropy change of CO2 adsorption of pure gases and binary gas mixtures, CO2 molecules form a much more stable rearrangement than CH4 and N2. Based on what was said, CNTs can be used to make structures with high CO2 adsorption capabilities by utilizing their excellent properties in gas separation. It is also possible to achieve an effective and economical adsorption structure by pyrolyzing cellulose, a cheap and readily available material.
