Adsorption And Separation Of CO₂/CH₄, CO₂/H₂ And CO₂/N₂ On Activated Carbon Beads With High Bet Specific Surface Area: Experiment And Modeling

Global warming is mainly attributed to the emission of CO2. Therefore, the carbon dioxide capture technologies (Carboon capture storage, CCS) are paied much attention. Among them, the physical adsorption method is regarded as one of the more promising technologies for its environmental advantages. In this work, the adsorption separation of CO2/CH4,CO2/H2 and CO2/N2 are discussed on the activated carbon beads(ACB-5) prepared by our group experimentally and theoretically. The main content can be summarized as follows:1. The adsorption isotherms of pure gases (CH4,CO2 and N2) and their mixtures are measured using the high-precision intelligent gravimetric analyzer. The results show that the adsorption amount of pure CO2,CH4 and N2 can reach up to 16.63,7.8 and 3.5mmol/g, with T=298K,P=1.3MPa, respectively, which indicates that theACBs are an good candidate for CH4 and CO2 storage.2. Based on the experimental data, the pure component are calculated by double Langmuir and DSLF (dual-site Langmuir-Freundlich equation) adsorption models combined with IAST(ideal adsorbed solution theory). The adsorption capacity and selectivity of the binary mixture of CH4/CO2 (XCH4: XCO2=70%:30%,XCH4:XCO2=85%:15%) are calculated. The result shows that the selectivity of CO2 over CH4 on ACBs can reach up to 5.28 with the mole fraction of XCH4:XCO2=70%:30%,T=298K and P=1.3MPa, which indicates that the ACBs is an excellent candidate for CO2 separation for CO2/ CH4 mixture.3.Grand canonical Monte Carlo(GCMC)method is adopted to calculated the selectivities of C02 over CH4(XCH4:XCO2=70%:30%,XCH4:XCO2=85%: 15%),N2(XN2:XCO2=50%:50%,XN2:XCO2=80%:20%) and H2/CO2 (XH2:XCO2=70%:30%,XCH2:XCO2=90%:10%),respectively.The selectivities of CO2 over CH4,N2 and H2 can reach up to 5.41,33 and 50 with the mole fraction of XCH4:XCO2=70%:30%,XN2:XCO2=50%:50% and XH2:XCO2=70%:30%,T=298K,P=1.3MPa and H=2.89nm,respectively.