Chloride and Hydride Transfer as Keys to Catalytic Upcycling of Polyethylene into Liquid Alkanes
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- Institute for Integrated Catalysis Pacific Northwest National Laboratory (PNNL) Richland Washington 99354 USA, Department of Chemistry and Catalysis Research Center Technical University of Munich (TUM) Lichtenbergstrasse 4 85747 Garching Germany
- Department of Chemistry and Catalysis Research Center Technical University of Munich (TUM) Lichtenbergstrasse 4 85747 Garching Germany
- Institute for Integrated Catalysis Pacific Northwest National Laboratory (PNNL) Richland Washington 99354 USA
- Institute for Integrated Catalysis Pacific Northwest National Laboratory (PNNL) Richland Washington 99354 USA, The Gene and Linda Voiland School of Chemical Engineering and Bioengineering Washington State University Pullman Washington 99164 USA
- Department of Chemical and Biological Engineering Princeton University Princeton New Jersey 08544 USA
- Department of Chemical Engineering Columbia University New York 10027 USA
Abstract Transforming polyolefin waste into liquid alkanes through tandem cracking‐alkylation reactions catalyzed by Lewis‐acid chlorides offers an efficient route for single‐step plastic upcycling. Lewis acids in dichloromethane establish a polar environment that stabilizes carbenium ion intermediates and catalyzes hydride transfer, enabling breaking of polyethylene C−C bonds and forming C−C bonds in alkylation. Here, we show that efficient and selective deconstruction of low‐density polyethylene (LDPE) to liquid alkanes is achieved with anhydrous aluminum chloride (AlCl 3 ) and gallium chloride (GaCl 3 ). Already at 60 °C, complete LDPE conversion was achieved, while maintaining the selectivity for gasoline‐range liquid alkanes over 70 %. AlCl 3 showed an exceptional conversion rate of 5000 , surpassing other Lewis acid catalysts by two orders of magnitude. Through kinetic and mechanistic studies, we show that the rates of LDPE conversion do not correlate directly with the intrinsic strength of the Lewis acids or steric constraints that may limit the polymer to access the Lewis acid sites. Instead, the rates for the tandem processes of cracking and alkylation are primarily governed by the rates of initiation of carbenium ions and the subsequent intermolecular hydride transfer. Both jointly control the relative rates of cracking and alkylation, thereby determining the overall conversion and selectivity.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 2324680
- Alternate ID(s):
- OSTI ID: 2324681
- Journal Information:
- Angewandte Chemie, Journal Name: Angewandte Chemie Journal Issue: 17 Vol. 136; ISSN 0044-8249
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- Germany
- Language:
- English
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