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Tapered element oscillating microbalance (TEOM) studies of isobutane, n-butane and propane sorption in β- and Y-zeolites

Authors

  • Kening Gong,

    1. Center for Environmentally Beneficial Catalysis and Dept. of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS 66045
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  • Bala Subramaniam,

    Corresponding author
    1. Center for Environmentally Beneficial Catalysis and Dept. of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS 66045
    • Center for Environmentally Beneficial Catalysis and Dept. of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS 66045
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  • Palghat A. Ramachandran,

    1. Center for Environmentally Beneficial Catalysis and Dept. of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130
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  • Keith W. Hutchenson

    1. DuPont Co., Wilmington, DE 19880
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Abstract

A TEOM is used to elucidate the adsorption/desorption characteristics of alkylation reactants on USY- and β-zeolites. Equilibrium adsorption isotherms were obtained on USY- and β-zeolites using n-butane, isobutane and propane as proxy reactant molecules (T = 303–398 K, adsorbate partial pressure 0–1.2 bar). Analysis of the transient adsorption/desorption profiles of these molecules from either a bed of the zeolite or pelletized particles of the crystals (with mean size < 1 μm) demonstrate that diffusion in the secondary meso-/macroporous structure formed in the packing or the pellets controls the overall sorption rates. The experimental adsorption/desorption profiles from the pelletized zeolites were regressed with available mathematical models to obtain effective meso-/macropore diffusivities for reactant molecules, and nearly perfect fits of the experimental and the modeled profiles. Taking into account the dead volume in the system, a criterion for reliable measurements of either micropore or mesopore diffusivities by the TEOM technique is derived. © 2009 American Institute of Chemical Engineers AIChE J, 2010

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