Adsorption of CH4-CF4 mixtures in silicalite: Simulation, experiment, and theory

Matthias Heuchel*, Randall Q. Snurr, Eckhard Buss

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

122 Scopus citations

Abstract

Grand canonical Monte Carlo (GCMC) simulations of binary Lennard-Jones mixtures in the zeolite silicalite have been used to predict the adsorption of CFU and CF4 mixtures as a function of gas phase composition, total pressure, and temperature. For single components and mixtures, predictions of adsorption isotherms and isosteric heats are in good agreement with experiment at room temperature. Within the experimental pressure range of 0 to 17 bar, the mixtures are well described by the ideal adsorbed solution (IAS) theory. For very high loading, deviations from IAS theory appear. The configurations generated in the simulation were used to calculate sorbate-zeolite interaction energy distributions for different types of siting locations within the zeolite pores. These distributions display a pore shape related energetic heterogeneity in different regions of silicalite. Near saturation at a total loading of 12 molecules per unit cell, the shape of the observed energy distribution is relatively independent of the composition in the pore. Nevertheless, the energetic heterogeneity is responsible for a mild segregation in the adsorbed mixtures, with methane adsorbed preferentially in the silicalite zigzag channels and CF4 preferentially in the straight channels.

Original languageEnglish (US)
Pages (from-to)6795-6804
Number of pages10
JournalLangmuir
Volume13
Issue number25
DOIs
StatePublished - Dec 10 1997

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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