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

Abstract

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 adsorptio...