Validation of the CO2/N2O Analogy Using Molecular Simulation

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• 作者：Qu Chen ; Sayee Prasaad Balaji ; Mahinder Ramdin ; Juan Jos茅 Guti茅rrez-Sevillano ; Andr茅 Bardow ; Earl Goetheer ; Thijs J. H. Vlugt
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2014
• 出版时间：November 19, 2014
• 年：2014
• 卷：53
• 期：46
• 页码：18081-18090
• 全文大小：338K
• ISSN：1520-5045

文摘

CO₂ readily reacts in aqueous amine solutions. The properties of free CO₂ in amine solutions are therefore difficult to obtain directly and are often predicted from the nonreacting molecule N₂O due to the similarities in mass and structure. This often-used empirical 鈥淐O₂/N₂O analogy鈥?is verified in this work using molecular simulation. Continuous fractional component Monte Carlo (CFCMC) simulations in the osmotic ensemble were used to compute the Henry coefficients of CO₂ and N₂O in the solvents water, ethanol, n-heptane, and a 30% aqueous MEA solution at a temperature of 303 K. Molecular dynamics (MD) simulations were performed to compute the self-diffusivities of CO₂ and N₂O in the aforementioned solvents at 303 K. Different force fields for CO₂ and water were used. The computed Henry coefficients and self-diffusivities of CO₂ and N₂O in the solvents are in good agreement with available experimental data. The simulation results indicate that the CO₂/N₂O analogy is valid for aqueous MEA solution at 303 K. The Henry coefficient and self-diffusivity ratios of CO₂ to N₂O in water and 30% MEA solution are approximately 0.77 and 1.1, respectively. Additional simulations where all the amines have reacted with CO₂ confirm that reactions have little impact on the physical absorption and diffusion properties of CO₂.