Intrapellet diffusivities from TAP pulse responses via moment-based analysis

Authors

  • A. H. J. Colaris,

    1. Eindhoven University of Technology, Laboratory of Chemical Reactor Engineering, 5600 MB Eindhoven, The Netherlands
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  • J. H. B. J. Hoebink,

    Corresponding author
    1. Eindhoven University of Technology, Laboratory of Chemical Reactor Engineering, 5600 MB Eindhoven, The Netherlands
    • Eindhoven University of Technology, Laboratory of Chemical Reactor Engineering, 5600 MB Eindhoven, The Netherlands
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  • M. H. J. M. de Croon,

    1. Eindhoven University of Technology, Laboratory of Chemical Reactor Engineering, 5600 MB Eindhoven, The Netherlands
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  • J. C. Schouten

    1. Eindhoven University of Technology, Laboratory of Chemical Reactor Engineering, 5600 MB Eindhoven, The Netherlands
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Abstract

Moment-based analysis was applied to determine successfully inter- and intrapellet diffusion coefficients from experimental TAP outlet pulse responses over a one-zone bed with porous particles. Different temperatures, gas molar masses, and pellet sieve fractions were used to validate the Knudsen diffusion relation for inert gases inside porous catalyst pellets. The zeroth to third moments of the outlet pulse response were analytically derived for rectangular, cylindrical and spherical pellets. The third moment provides a significantly more accurate access to the intrapellet diffusivity than the second moment does. The experimental window of the TAP reactor is explored for porous silica as catalyst support bed filling. The relevance of concentration gradients inside the pellet is illustrated with model simulations.

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