Tailored Mesoporosity Development in Zeolite Crystals by Partial Detemplation and Desilication

Authors

  • Javier Pérez-Ramírez,

    Corresponding author
    1. Institute of Chemical Research of Catalonia (ICIQ) Avinguda Països Catalans 16, Tarragona, 43007 (Spain)
    2. Catalan Institution for Research and Advanced Studies (ICREA) Passeig Lluís Companys 23, Barcelona, 08010 (Spain)
    • Institute of Chemical Research of Catalonia (ICIQ) Avinguda Països Catalans 16, Tarragona, 43007 (Spain).
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  • Sònia Abelló,

    1. Institute of Chemical Research of Catalonia (ICIQ) Avinguda Països Catalans 16, Tarragona, 43007 (Spain)
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  • Adriana Bonilla,

    1. Institute of Chemical Research of Catalonia (ICIQ) Avinguda Països Catalans 16, Tarragona, 43007 (Spain)
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  • Johan C. Groen

    1. Delft Solids Solutions B.V. Rotterdamseweg 183c, 2629 HD Delft (The Netherlands)
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Abstract

Partial detemplation of zeolites followed by desilication in alkaline medium is demonstrated as a powerful and elegant approach to design hierarchical zeolites with tailored degree of mesoporosity. This achievement, illustrated for large beta crystals, is based on the fact that the template-containing zeolite is virtually inert to Si leaching upon treatment in aqueous NaOH solutions. Partial removal of the structure-directing agent creates regions in the crystal susceptible to mesopore formation by subsequent desilication, while template-containing regions are protected from silicon extraction. Variation of the calcination temperature in the range 230–550 °C determines the amount of template removed and enables control of the extent of mesopore formation in the zeolite (20–230 m2 g−1) upon alkaline treatment. The functionality of the introduced mesoporosity in the hierarchical beta crystals is demonstrated by the improved performance in the catalytic pyrolysis of low-density polyethylene. The partial detemplation–desilication treatment enhances the tuning options of this demetallation method.

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