Catalytic Pyrolysis of Polyethylene with Microporous and Mesoporous Materials: Assessing Performance and Mechanistic Understanding

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Abstract

Testing the catalytic performance for the catalytic pyrolysis of plastic waste is hampered by mass transfer limitations induced by a size mismatch between the catalyst′s pores and the bulky polymer molecules. To investigate this aspect, the catalytic behaviour of a series of microporous and mesoporous materials was assessed in the catalytic pyrolysis of polyethylene (PE). More specifically, a mesoporous material, namely sulfated zirconia (Zr(SO4)2) on SBA-15, was synthesized to increase the pore accessibility, which reduces mass transfer limitations and thereby enables to better assess the effect of active site density on catalyst activity. To demonstrate the potential of this approach, the mesoporous SBA-15 catalysts were compared to a series of microporous zeolite Y catalysts. Using the degradation temperature during thermogravimetric analysis (TGA) as a measure of activity, no correlation between acidity and activity was observed for microporous zeolite Y. However, depending on the Mw of PE, the reactivity of the mesoporous catalysts increased with increasing Zr(SO4)2 weight loading, showing that utilizing a mesoporous catalyst can overcome the accessibility limitations at least partially, which was further confirmed by polymer melt infiltration and in situ X–ray diffraction. Detailed product analysis revealed that more aromatics and coke deposits were produced with the more acidic zeolite Y materials. The mesoporous material remained active and structurally intact over multiple cycles and catalyses PE degradation via acid- and radical-based pathways.

Original languageEnglish
Article numbere202401141
JournalChemSusChem
DOIs
Publication statusE-pub ahead of print - 10 Sept 2024

Bibliographical note

Publisher Copyright:
© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.

Funding

The authors acknowledge Angela Melcherts (Utrecht University, UU) for performing the HAADF\u2010STEM(EDX) measurements, while Jelle Bos (UU), En Chen (UU), Joyce Kromwijk (UU), Nicolette Maaskant (UU), Sebastian Rejman (UU) and Chunning Sun (UU) are acknowledged for the N\u2010physisorption measurements. This work was supported by TNO/Brightsite and the Netherlands Organization for Scientific Research (NWO) in the frame of a Gravitation Program, MCEC (Netherlands Center for Multiscale Catalytic Energy Conversion). B.M.W and I.V. are supported by the Advanced Research Center (ARC) Chemical Buildings Blocks Consortium (CBBC), a public\u2010private research consortium in The Netherlands (arc\u2010cbbc.nl). I.V. also acknowledges a Veni grant from NWO (VI.Veni.202.191). 2

FundersFunder number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek
Brightsite
MCEC
Netherlands Center for Multiscale Catalytic Energy ConversionVI.Veni.202.191

    Keywords

    • acidity
    • catalytic pyrolysis
    • chemical recycling of plastics
    • porosity
    • zeolites

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