In-line NMR Guides Orthogonal Transformation of Real-life Plastics
Researchers reported a advance in the indentification, separation, and catalytic transformation of real-life plastic waste mixtures.
The global accumulation of plastic waste poses a serious threat to wildlife and ecosystems. Catalytic processes that convert plastic waste into valuable chemicals and fuels offer a promising solution. However, the recycling of real-life plastic waste mixtures remains a challenge due to their highly diverse composition and structural complexity. Accurate identification of the components within plastic waste mixtures is a prerequisite for their effective separation and recycling.Solid-state nuclear magnetic resonance (NMR) spectroscopy, which has the advantage of directly analyzing insoluble samples, provides detailed information into local atomic structure, molecular motion, interactions, and chemical environment—making it a powerful tool for studying complex polymer systems.In a study published in Nature, Prof. XU Shutao from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with the team of Prof. WANG Meng and Prof. MA Ding from Peking University, reported a advance in the indentification, separation, and catalytic transformation of real-life plastic waste mixtures.The researchers utilized an innovative solid-state NMR method—1H-13C Frequency Switched Lee Goldburg Heteronuclear Correlation (FSLG-HETCOR) NMR. By optimizing key parameters such as spinning rate, contact time, and homonuclear decoupling field strength, and using 13C-labeled tyrosine hydrochloride as a reference, the researchers obtained high-resolution “fingerprint” spectra of individual plastic components from an eight-plastic mixture containing PS (polystyrene), PLA (polylactic acid), PU (polyurethane), PC (polycarbonate), PVC (polyvinyl chloride), PET (polyethylene terephthalate), PE (polyethylene), and PP (polypropylene).The method obtained spectra with high signal intensity and good resolution in the indirect dimension, allowing for precise identification of various functional groups in the plastic mixture and enabling real-time tracking of their chemical evolution.Furthermore, the researchers demonstrated the feasibility, effectiveness, and universality of this method by monitoring the full catalytic separation and transformation of real-life plastic waste mixtures. Their NMR-based analysis enabled the mapping of each step in the conversion process—from complex mixtures to multiple high-value chemicals products.By identifying characteristic functional group signals in plastic waste mixtures, the researchers laid a solid foundation for their effective separation and transformation. This work paves the way for integrating existing transformation processes into a unified framework, providing technical support for scalable industrial solutions to global plastic pollution."Solid-state NMR provides a powerful way to identify individual components in plastic waste mixtures. It acts as a 'guiding eye' for the separation and catalytic transformation processes, laying the technological foundation for real-life solutions to plastic pollution," said Prof. XU.