Adsorption And Separation Process Of CO₂ By Molecular Simulation

The increase of CO2 concentration in the atmosphere is generally considered to be one of the most important reasons for global warming. How to reduce CO2 emissions to reduce the CO2 concentration in the atmosphere is a challenging problem the whole world faced. In order to develop new effective CO2 adsorption and separation methods, it is valuable and meaningful to study the adsorption properties of CO2 and mixtures in different adsorbents.In this paper, zeolites and organic frameworks were used as two different effective adsorbents, while CO2, CH4, N2 were used as adsorbates. The adsorption behaviors of pure CO2, CH4, N2 and their mixtures in MFI zeolites and organic frameworks were studied using Grand Canonical Monte Carlo method (GCMC). Conclusions were gained through caculation and analysis:(1)The adsorption isotherms of pure CO2, CH4, N2 all belong to Lamuir type, the adsorption amounts of pure component are higher at low pressure, while the adsorption amounts of CO2 was highter than CH4 and N2.(2)The mixtures of CO2, CH4, N2 presented evident competitive adsorption behaviors in MFI zeolites, the adsorption amounts of CO2 was highter than CH4 and N2, MFI zeolites had great adsorption selectivity to CO2.(3)According to Lowenstein principles, the all-silica MFI zeolite was modified by Na+, the presence of Na+ enhanced the adsorption ability and selectivity of CO2, Na+ had no influence to the adsorption propertities of CH4 and N2.(4)Mass clouds distributions shows, the mass clouds in all-silica zeolites were well-distributed, while the mass clouds in Na+ modified MFI zeolites were different, the adsorption sites around Na+ were enhanced and CO2 was first adsorbed in these high sites at low pressures.(5)Adsorption amounts of pure CO2, CH4, N2 in metal-organic framework MOF-14 and covalent-organic framework were higher than MFI zeolites, while the adsorption amounts of CH4 was highter than CO2 and N2.(6)The mixtures of CO2, CH4, N2 also presented evident competitive adsorption behaviors in COF-108 and MOF-14 frameworks, the adsorption amounts of CO2 and CH4 were highter than N2, while their selectivity of CO2, CH4 was weaker than MFI zeolites.(7)The adsorption sites of CO2, CH4, N2in MOF-14 lied in central channels and side channels, while the adsorption sites of CO2, CH4, N2 in COF-108 lied in the whole frameworks...