Adsorption of Cyclohexane in Pure Silica Zeolites: High‐Throughput Computational Screening Validated by Experimental Data

Abstract

Adsorption of cyclohexane in pure silica zeolites was studied experimentally and by molecular simulations. Based on the adsorption isobars obtained from the quasi‐equilibrated temperature adsorption and desorption (QE‐TPDA) measurements and reported adsorption isotherms for high‐silica zeolites Y, ZSM‐5, and ZSM‐11 we refined Lennard‐Jones parameters for guest‐host interactions available in the literature. Adsorption of cyclohexane from equimolar mixture of twisted‐boat and chair conformations has been screened in 171 pure silica zeolitic structures using grand canonical Monte Carlo simulations. Almost 20 frameworks showing extraordinary preference for adsorption of the chair conformation over the twisted boat one or vice versa were found. This selectivity was attributed to the geometry of channels and cavities present in the pore structures, as all t‐boat selective structures possess channels or cavities of 8.3–9.1 Å. We also differentiated ways of chair‐selectivity depending on the size and shape of the channels or cavities and also on the arrangement of the guest molecules in the pores.

Adsorption of Alkanes in Zeolites LTA and FAU: Quasi-Equilibrated Thermodesorption Supported by Molecular Simulations

“…Nonaveraged QE-TPDA profiles recorded for nC5, nC8, and nC10 are collated in Figure S3 of the Supporting Information. Similar differences between the first and the following maxima were also observed for adsorption of bulky moleculessuch as 2,2-dimethylbutane (22DMB) or cyclohexanein zeolite MFI, 39,71 which may be related to diffusion limitations. As initial adsorption takes place at RT, the structure is not fully "opened" to the guest molecules.…”

Recent advances in the continuous fractional component Monte Carlo methodology

“…Due to the increase in computational power, the CFCMC method can be applied to complex systems, for instance simulation of adsorption of different species in nanoporous materials in the grand-canonical ensemble and osmotic ensemble and computation of thermodynamic properties of components in confinement [63,121,122,187,[190][191][192][193]. In these simulations, a single fractional molecule per component type can be used to facilitate molecule exchanges between the ideal gas reservoir and the nanoporous structure.…”

Kinetic Molecular Sieving of Cyclopentane/Neohexane Mixtures by the MFI Zeolite with Intersecting 10-Ring Channels

“…The interactions of adsorbates–adsorbates and adsorbates-adsorbents were described by the Lennard-Jones (LJ) potentials. The LJ parameters for the atoms in silicalite-1 and neohexane were taken from studies by Dubbeldam et al The LJ parameters of CH 2 in cyclopentane for the interactions between the guest molecules are 50.37 K for ε k B –1 and 3.93 Å for σ . For the interactions between CH 2 in cyclopentane and O atoms in silicalite-1, ε k B –1 [K] is 73 and σ [Å] is 3.35.…”

“…The LJ parameters for the atoms in silicalite-1 and neohexane were taken from studies by Dubbeldam et al 26 The LJ parameters of CH 2 in cyclopentane for the interactions between the guest molecules are 50.37 K for εk B −1 and 3.93 Å for σ. 27 For the interactions between CH 2 in cyclopentane and O atoms in silicalite-1, εk B −1 [K] is 73 and σ [Å] is 3.35. The cutoff distance was set as 12 Å for van der Waals interactions.…”