Diffusion of n-butane/iso-butane mixtures in silicalite-1 investigated using infrared (IR) microscopy

  • chair:

    Chmelik, C. / Heinke, L. / van Baten, J. / Krishna, R. (2009)

  • place:

    Microporous and Mesoporous Materials 125 (2009), 1–2, 11–16

  • Date: 2009
  • Chmelik, C. / Heinke, L. / van Baten, J. / Krishna, R. (2009): „Diffusion of n-butane/iso-butane mixtures in silicalite-1 investigated using infrared (IR) microscopy“. In: Microporous and Mesoporous Materials 125 (2009), 1–2, 11–16

Abstract

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Adsorption and diffusion of n-butane/iso-butane mixtures in individual silicalite-1 crystals has been investigated using infrared (IR) microscopy. The equilibrium sorption isotherm for an equimolar gas phase mixture is calculated using Configurational Bias Monte-Carlo simulations. The comparison between simulation results and the experimental data enabled the determination of absolute values of concentration in the IR experiments.

n-Butane uptake under presence of iso-butane and, vice versa, iso-butane uptake under presence of n-butane have been studied experimentally. It is shown that the n-butane counter-uptake is not limited by the n-butane diffusivity, but by the availability of free sites, which is, in turn, determined by the mobility of iso-butane. A site-percolation threshold, given by the number of iso-butane molecules blocking the ‘traffic junctions’ of the channel network, has been employed for explaining the occurrence of network regions which are initially inaccessible for n-butane in the counter-uptake process.