Tandem Heterogeneous Catalysis for Polyethylene Depolymerization via an Olefin-Intermediate Process

Lucas Ellis, Sara Orski, Grace Kenlaw, Andrew Norman, Kathryn Beers, Yuriy Román-Leshkov, Gregg Beckham

Research output: Contribution to journalArticlepeer-review

79 Scopus Citations

Abstract

The accumulation of plastic waste in the environment has prompted the development of new chemical recycling technologies. A recently reported approach employed homogeneous organometallic catalysts for tandem dehydrogenation and olefin cross metathesis to depolymerize polyethylene (PE) feedstocks to a mixture of alkane products. Here, we build on that prior work by developing a fully heterogeneous catalyst system using a physical mixture of SnPt/γ-Al2O3 and Re2O7/γ-Al2O3. This heterogeneous catalyst system produces a distribution of linear alkane products from a model, linear C20 alkane, n-eicosane, and from a linear PE substrate (which is representative of high-density polyethylene), both in an n-pentane solvent. For the PE substrate, a molecular weight decrease of 73% was observed at 200 °C in 15 h. This type of tandem chemistry is an example of an olefin-intermediate process, in which poorly reactive aliphatic substrates are first activated through dehydrogenation and then functionalized or cleaved by a highly-active olefin catalyst. Olefin-intermediate processes like that examined here offer both a selective and versatile means to depolymerize polyolefins at lower severity than traditional pyrolysis or cracking conditions.

Original languageAmerican English
Pages (from-to)623-628
Number of pages6
JournalACS Sustainable Chemistry and Engineering
Volume9
Issue number2
DOIs
StatePublished - 18 Jan 2021

Bibliographical note

Publisher Copyright:
© 2021 American Chemical Society.

NREL Publication Number

  • NREL/JA-2A00-78168

Keywords

  • Dehydrogenation
  • Olefin cross metathesis
  • Olefin-intermediate process
  • Plastics upcycling
  • Polyethylene

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