Development of a Transferable Guest−Host Force Field for Adsorption of Hydrocarbons in Zeolites. II. Prediction of Alkenes Adsorption and Alkane/Alkene Selectivity in Silicalite

Abstract

Alkene pure components and alkane/alkene binary mixtures adsorption isotherms are computed by grand canonical Monte Carlo simulations. The anisotropic united atom potential optimized from experimental isotherms of butane in silicalite is used without further adjustement to predict the behavior of alkane and alkene molecules in silicalite. Simulated results are in good agreement with available experimental data. Selectivity of silicalite toward alkane/alkene mixtures is driven by enthalpic effects at low coverage and by entropic effects at saturation. An interesting reversal of ethane/ethene selectivity with temperature is predicted.

Molecular Simulations of Zeolites: Adsorption, Diffusion, and Shape Selectivity

“…90 The crossing of the lines gives the parameters for which both the Henry coefficient and heat of adsorption agree with the experimental results. For comparison, the stars are the parameters of the model proposed by Bezus et al, 74 Goodbody et al, 91 Hufton et al, 92 and Demontis et al 93,74,[91][92][93] The triangle gives the model of Dubbeldam et al 94 Pascual and co-workers 95,96 used an approach that relies less on the availability of accurate experimental data. This method relies on the assumption that alkane-zeolite interactions can be estimated from the Lorentz-Berthelot mixing rules for the anisotropic united-atom model:…”

Adsorption and Reaction in Confined Spaces

“…The gas phase adsorption of alkanes, alkenes and aromatics on faujasites in has been studied frequently [40][41][42][43][44][45][46][47][48][49][50][51][52][53]. Generally, alkenes and aromatics are more strongly adsorbed compared to the apolar alkanes because of their electrostatic interactions with the zeolite cations.…”

Computer Simulations of Shape Selectivity Effects

“…This procedure uniquely determined the adsorbent-adsorbate interaction parameters, and is very sensitive to the size parameter as the inflection points in the isotherms are often related to a subtle interplay between different adsorption sites. Several alternative force fields have been developed that also provide an accurate description of the experimental adsorption isotherms [104,105].…”