Evaluating mixture adsorption models using molecular simulation

Abstract

The design of adsorption-based separation processes using novel adsorbents requires reliable data for the adsorption of fluid mixtures on candidate adsorbents. Due to the difficulty of generating sufficient data across possible operating conditions, process designs generally rely on interpolation of pure-component data using a model, most commonly ideal adsorbed solution theory (IAST), and related theories. There are many cases where IAST fails to provide an adequate description of mixture adsorption, usually due to the fact that practical adsorbents do not have uniform surfaces. We have evaluated the use of a segregated version of IAST, where competition is assumed to occur at isolated adsorption sites. This simple modification can provide the correct description of adsorption across a large range of pressures using ideal isotherm models. We also demonstrate the importance of identifying multiple sites even for weakly adsorbing components to provide the correct behavior at high pressure.

Competitive adsorption and selectivity of benzene and water vapor on the microporous metal organic frameworks (HKUST-1)

“…In our previous work, we used this theory to estimate the adsorption selectivity of CO 2 /N 2 in the ZIF-8 and matched very well with the results obtained from Henry's constants [42]. Recently, this method is now being adopted by many research groups to investigate the behavior of the mixture competitive adsorption [43,44].…”

Large-Scale Screening of Zeolite Structures for CO2 Membrane Separations

“…The mixture isotherms were obtained from the computed pure isotherm data using the IAST, which has been demonstrated to be generally applicable to make good predictions about mixture behaviors for various porous materials. 28 It is important, however, to note that some particular cases may need some variant theories of IAST, 36 which is regarded to be out of the scope for this current work.…”

Modeling of molecular gas adsorption isotherms on porous materials with hybrid PC-SAFT–DFT

“…Meanwhile, the process of enhanced coal-bed methane or shale gas production also relates to the gas adsorption on nano-porous materials. Although a lot of experimental measurements have been carried out, the prediction of gas adsorption with modeling is still a challenging task [6][7][8].…”