Elucidating alkane adsorption in sodium-exchanged zeolites from molecular simulations to empirical equations

E. García-Pérez, I. M. Torréns, S. Lago, D. Dubbeldam, T. J.H. Vlugt, T. L.M. Maesen, B. Smit, R. Krishna, Sofia Calero

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)

Abstract

Configurational-bias Monte Carlo (CBMC) simulations provide adsorption isotherms, Henry coefficients and heats of adsorption of linear alkanes in sodium-exchanged MFI- and FAU-type zeolites. These simulations were carried out using our newly developed force field that reproduces experimental sodium positions in the dehydrated zeolites, and successfully predicts alkane adsorption properties over a wide range of sodium cation densities, temperatures, and pressures. We derived empirical expressions from the simulation data to describe the adsorption of linear alkanes in MFI- and FAU-type zeolites. These expressions afford a suitable substitute for complex CBMC simulations. In the low coverage regime we provide simple expressions that adequately describe the Henry coefficient and adsorption enthalpy of n-alkanes as a function of sodium density and temperature. The predicted Henry coefficients and heats of adsorption compare extremely well to available experimental data. In the high coverage regime we provide an expression for saturation capacities of linear alkanes in the zeolite. This expression, combined with the expression for the Henry coefficients, provides of the complete adsorption isotherms of pure adsorbents and mixtures, in good agreement with the adsorption isotherms obtained from CBMC.

Original languageEnglish
Pages (from-to)716-722
Number of pages7
JournalApplied Surface Science
Volume252
Issue number3
DOIs
Publication statusPublished - 31 Oct 2005
Externally publishedYes

Keywords

  • CBMC
  • Empirical equations
  • Molecular simulations

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