Selective Lanthanide-Organic Catalyzed Depolymerization of Nylon-6 to ϵ-Caprolactam

Lukas Wursthorn; Kristen Beckett; Jacob O. Rothbaum; Robin M. Cywar; Clarissa Lincoln; Yosi Kratish; Tobin J. Marks

doi:10.1002/anie.202212543

Selective Lanthanide-Organic Catalyzed Depolymerization of Nylon-6 to ϵ-Caprolactam

Lukas Wursthorn, Kristen Beckett, Jacob O. Rothbaum, Robin M. Cywar, Clarissa Lincoln, Yosi Kratish^*, Tobin J. Marks^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

54 Scopus citations

Abstract

Nylon-6 is selectively depolymerized to the parent monomer ϵ-caprolactam by the readily accessible and commercially available lanthanide trisamido catalysts Ln(N(TMS)₂)₃ (Ln=lanthanide). The depolymerization process is solvent-free, near quantitative, highly selective, and operates at the lowest Nylon-6 to ϵ-caprolactam depolymerization temperature reported to date. The catalytic activity of the different lanthanide trisamides scales with the Ln³⁺ ionic radius, and this process is effective with post-consumer Nylon-6 as well as with Nylon-6+polyethylene, polypropylene or polyethylene terephthalate mixtures. Experimental kinetic data and theoretical (DFT) mechanistic analyses suggest initial deprotonation of a Nylon terminal amido N−H bond, which covalently binds the catalyst to the polymer, followed by a chain-end back-biting process in which ϵ-caprolactam units are sequentially extruded from the chain end.

Original language	English (US)
Article number	e202212543
Journal	Angewandte Chemie - International Edition
Volume	62
Issue number	4
DOIs	https://doi.org/10.1002/anie.202212543
State	Published - Jan 23 2023

Funding

Financial support by the Office of Basic Energy Sciences, U.S. Department of Energy (DE‐FG02‐03ER15457) to the Institute for Catalysis in Energy Processes (ICEP) at Northwestern University (Y.K.), the NSF CAT program under grant CHE‐1856619 (J.O.R.) and the RePLACE (Redesigning Polymers to Leverage A Circular Economy), funded by the Office of Science of the U.S. Department of Energy via award no. DE‐SC0022290 (T.J.M., L.W.; K.B.) are gratefully acknowledged. Purchase of the NMR instrumentation at IMSERC was supported by NSF (CHE‐1048773). This research was supported in part by the computational resources provided by the Quest High‐Performance Computing Facility at NU, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern U. Information Technology. L.W. gratefully acknowledges fellowship support by the Cusanuswerk‐ Bischöfliche Studienförderung. This work was authored in part (R.M.C. and C.L) by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE‐AC36‐08GO28308, and was performed as part of the BOTTLE Consortium. Funding was provided by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), Advanced Manufacturing Office (AMO), and Bioenergy Technologies Office (BETO). The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. Financial support by the Office of Basic Energy Sciences, U.S. Department of Energy (DE-FG02-03ER15457) to the Institute for Catalysis in Energy Processes (ICEP) at Northwestern University (Y.K.), the NSF CAT program under grant CHE-1856619 (J.O.R.) and the RePLACE (Redesigning Polymers to Leverage A Circular Economy), funded by the Office of Science of the U.S. Department of Energy via award no. DE-SC0022290 (T.J.M., L.W.; K.B.) are gratefully acknowledged. Purchase of the NMR instrumentation at IMSERC was supported by NSF (CHE-1048773). This research was supported in part by the computational resources provided by the Quest High-Performance Computing Facility at NU, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern U. Information Technology. L.W. gratefully acknowledges fellowship support by the Cusanuswerk- Bischöfliche Studienförderung. This work was authored in part (R.M.C. and C.L) by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308, and was performed as part of the BOTTLE Consortium. Funding was provided by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), Advanced Manufacturing Office (AMO), and Bioenergy Technologies Office (BETO). The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government.

Keywords

Chemical Recycling
Green Chemistry
Lanthanides
Nylon
Plastic

ASJC Scopus subject areas

Catalysis
General Chemistry

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1002/anie.202212543

Cite this

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title = "Selective Lanthanide-Organic Catalyzed Depolymerization of Nylon-6 to ϵ-Caprolactam",

abstract = "Nylon-6 is selectively depolymerized to the parent monomer ϵ-caprolactam by the readily accessible and commercially available lanthanide trisamido catalysts Ln(N(TMS)2)3 (Ln=lanthanide). The depolymerization process is solvent-free, near quantitative, highly selective, and operates at the lowest Nylon-6 to ϵ-caprolactam depolymerization temperature reported to date. The catalytic activity of the different lanthanide trisamides scales with the Ln3+ ionic radius, and this process is effective with post-consumer Nylon-6 as well as with Nylon-6+polyethylene, polypropylene or polyethylene terephthalate mixtures. Experimental kinetic data and theoretical (DFT) mechanistic analyses suggest initial deprotonation of a Nylon terminal amido N−H bond, which covalently binds the catalyst to the polymer, followed by a chain-end back-biting process in which ϵ-caprolactam units are sequentially extruded from the chain end.",

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AU - Kratish, Yosi

AU - Marks, Tobin J.

PY - 2023/1/23

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N2 - Nylon-6 is selectively depolymerized to the parent monomer ϵ-caprolactam by the readily accessible and commercially available lanthanide trisamido catalysts Ln(N(TMS)2)3 (Ln=lanthanide). The depolymerization process is solvent-free, near quantitative, highly selective, and operates at the lowest Nylon-6 to ϵ-caprolactam depolymerization temperature reported to date. The catalytic activity of the different lanthanide trisamides scales with the Ln3+ ionic radius, and this process is effective with post-consumer Nylon-6 as well as with Nylon-6+polyethylene, polypropylene or polyethylene terephthalate mixtures. Experimental kinetic data and theoretical (DFT) mechanistic analyses suggest initial deprotonation of a Nylon terminal amido N−H bond, which covalently binds the catalyst to the polymer, followed by a chain-end back-biting process in which ϵ-caprolactam units are sequentially extruded from the chain end.

AB - Nylon-6 is selectively depolymerized to the parent monomer ϵ-caprolactam by the readily accessible and commercially available lanthanide trisamido catalysts Ln(N(TMS)2)3 (Ln=lanthanide). The depolymerization process is solvent-free, near quantitative, highly selective, and operates at the lowest Nylon-6 to ϵ-caprolactam depolymerization temperature reported to date. The catalytic activity of the different lanthanide trisamides scales with the Ln3+ ionic radius, and this process is effective with post-consumer Nylon-6 as well as with Nylon-6+polyethylene, polypropylene or polyethylene terephthalate mixtures. Experimental kinetic data and theoretical (DFT) mechanistic analyses suggest initial deprotonation of a Nylon terminal amido N−H bond, which covalently binds the catalyst to the polymer, followed by a chain-end back-biting process in which ϵ-caprolactam units are sequentially extruded from the chain end.

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Selective Lanthanide-Organic Catalyzed Depolymerization of Nylon-6 to ϵ-Caprolactam

Abstract

Funding

Keywords

ASJC Scopus subject areas

UN SDGs

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CCDC 2191891: Experimental Crystal Structure Determination

Cite this

Selective Lanthanide-Organic Catalyzed Depolymerization of Nylon-6 to ϵ-Caprolactam

Abstract

Funding

Keywords

ASJC Scopus subject areas

UN SDGs

Access to Document

Other files and links

Fingerprint

Datasets

CCDC 2191891: Experimental Crystal Structure Determination

Cite this