【Frontiers in HaiChuan Chemical Technology】Peking University scientists solve the challenge of high-value recycling of mixed plastic waste

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Chinese scientists solve the challenge of high-value recycling of mixed plastic waste. June 27, 2025. Shared. Peking University announced that a team led by Professor Martin and Associate Researcher Wang Meng from the School of Chemistry and Molecular Engineering at Peking University has developed an orthogonal transformation strategy for real mixed plastic waste using nuclear magnetic resonance, enabling the efficient conversion of such waste into high-value chemicals. The research findings were published on June 26 in the journal Nature. The widespread use and massive disposal of plastics also make it one of the global environmental management challenges. Every year, the world produces over 400 million tons of new plastic products. These materials have advantages such as high strength and good stability, but once discarded, their durability and resistance to degradation cause them to remain in the natural environment for long periods, resulting in serious \"white pollution\". Currently, plastic waste recycling technologies mainly include physical recycling, thermal energy recovery, and chemical conversion recycling. Among these, chemical conversion recycling does possess great potential for recovering all chemical elements from waste plastics and turning them into high-value products, but most of the chemical recycling methods currently under development are only suitable for specific plastic structures. When the chemical conversion and recycling process is applied to real mixed plastic waste, it is often constrained by the complex composition and significant differences in properties of such waste; as a result, there are no universally applicable and controllable conversion methods, and to date, recycling and conversion have only been achieved for a few types of plastic products. This research achievement utilizes two-dimensional solid-state nuclear magnetic resonance technology to accurately identify the distribution of key functional groups in mixed plastics, such as ester bonds, aromatic rings, chloroalkanes, and alkyl chains. Based on this information, orthogonal chemical reaction pathways are designed; through the organic integration of multiple steps including solvent extraction, photocatalytic oxidation, catalytic amination, saponification, dehydrocoupling, and hydrocracking, the components are separated and transformed step by step, ultimately yielding various high-value chemicals. Starting from the model framework, the research team designed a comprehensive identification and transformation pathway. Subsequently, using a 20-gram sample of real mixed plastic waste from human life as an example, various plastics such as polystyrene, polylactic acid, polyurethane, polycarbonate, polyvinyl chloride, PET, and polyolefins were successfully orthogonally transformed to yield a variety of high-value chemicals including benzoic acid, phthalates, alanine, lactic acid, aromatic amine salts, bisphenol A, terephthalic acid, and C3-6 alkanes. This method is highly versatile and suitable for various real waste samples. Further research shows that this strategy is also applicable to various complex and real plastic waste samples from different sources, such as daily life, petrochemical industries, automobile repair, and the textile industry, which contain impurities such as printing pigments, dyes, plasticizers, and biomass. This study overcomes the technical barriers that have long hindered the high-value recycling of mixed plastic waste, by proposing an integrated approach that combines functional group identification, targeted formation of desired products, and the design of orthogonal reaction pathways, thus offering a new paradigm for the recycling of complex plastic waste.