(547b) Prediction of Multicomponent Gas Adsorption Equilibria and Heat of Adsorption from Pure Component Isotherms with Adsorption NRTL Model

In gas adsorption equilibria, successful engineering thermodynamic models should meet five criteria: (i) thermodynamic consistency, (ii) least numbers of physically significant adjustable parameters, (iii) applicability in both pure and multicomponent adsorption, (iv) predictivity of multicomponent adsorption equilibria from its pure component isotherms, and (v) predictivity of isosteric heat of adsorption for pure and multicomponent systems [1, 2]. Numerous researchers have proposed empirical and semi-empirical models such as Langmuir, Toth, and multisite Langmuir to represent pure and multicomponent gas adsorption equilibria [3-6]. However, to the best of our knowledge, none of the models fulfill all these requirements. To resolve this issue, recently we developed an adsorption non-random two liquid theory (aNRTL) activity coefficient model to account for specific adsorbate-adsorbent interactions in the adsorbate phase. In this work, we show the aNRTL model successfully represent pure component isotherms as well as isosteric heats of adsorption. We further show the estimated model parameters from pure component isotherms successfully predict the mixed-gas adsorption equilibria and the associated isosteric heats of adsorption. Meeting the five criteria for a successful engineering thermodynamic model for gas adsorption equilibria, the aNRTL model should serve well as a unifying thermodynamic framework to correlate and predict adsorption isotherms and to support modeling and simulation of adsorptive separation processes.

References

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