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Competitive Adsorption of CO2 over N2 in Asphaltene Slit Nanopores Studied by Molecular Simulation

Sun, Haoyang, Zhao, Hui, Qi, Na, Zhang, Kai, Wang, Qiaozhi, Li, Ying
Energy & fuels 2017 v.31 no.12 pp. 13979-13984
adsorption, asphaltenes, carbon dioxide, cost effectiveness, energy, flue gas, fuels, greenhouse effect, heat, molecular dynamics, nanopores, nitrogen, sorbents, temperature
CO₂ capture and sequestration (CCS) is recognized as one of the most promising alternatives to weaken the greenhouse effect, and nanoporous materials are regarded as the promising candidates; therefore, developing a new cost-effective sorbent to achieve CCS is crucial. In this study, asphaltene-based slit nanopores were used to simulate capturing of CO₂ from flue gas. The grand canonical Monte Carlo and molecular dynamics simulation methods were employed to examine the microscopic behaviors of CO₂ and N₂ in asphaltene slit nanopores. The isosteric heat of CO₂ and N₂ molecules adsorbed in asphaltene slit nanopores, the adsorption energy of a single molecule of CO₂ and N₂ adsorbed on the surface of asphaltene fragments, and the self-diffusion of CO₂ and N₂ molecules adsorbed in asphaltene slit nanopores were examined. Strong competitive adsorption of CO₂ over N₂ is found in a broad range of temperatures and pressures, and it was found that the temperature plays an important role on the competitive adsorption. This work demonstrates how the competitive adsorption of CO₂ over N₂ happened in asphaltene slit nanopores, which not only enriches the theoretical knowledge about gas behavior in asphaltenes but also gives the feasibility that the asphaltenes or asphaltene-based materials might be an interesting candidate for capturing CO₂ from flue gas.