Chemical Catalysis for Plastics Recycling and Upcycling

This manuscript demonstrates a single-step electrified approach using rapid joule heating over an H-ZSM-5 catalyst for effective deconstruction of polyolefin plastic waste into light olefins (C2–C4) in milliseconds.

Chemical recycling of polyester wastes is of great significance for sustainable development. Here the authors report a Ru and Mo dual-atom catalyst for reconstructing polyester wastes into diols in water under mild conditions.

To solve the serious problem of white plastic pollution many degradation routes are being investigated. Here the authors show a H₂-free low-cost Cu/SiO₂ catalyzed process to quantitatively convert polyethylene terephthalate into p-xylene and ethylene glycol in one pot with methanol as both the solvent and hydrogen source at 210 °C.

Polyolefins are a major fraction of plastic waste, yet their catalytic recycling is challenging due to their inert hydrocarbon structures. Here a well-defined supported organozirconium catalyst is shown to mediate the rapid hydrogenolytic cleavage diverse polyolefins under very mild conditions.

Alternating copolymerization of cyclic anhydrides and epoxides is an interesting platform for the synthesis of polyesters from renewable resources, but the near irreversibility of the copolymerization makes it challenging to develop chemically recyclable polyesters with easy-to-tune structure. Here, the authors develop a recyclable polyester library from alternating copolymerization of aldehyde and cyclic anhydride.

Chemical recycling of plastic wastes is of great significance for sustainable development, which also represents challenges and opportunities for synthesis of value-added chemicals. Here, the authors report a general strategy to degrade polyesters via directly breaking the C-O bond by nucleophilic substitution of halide anion of ionic liquids.

The catalytic conversion of polyolefins into gasoline-range alkanes requires a comprehensive understanding of the catalytically active species and their corresponding performance. Here the authors tackle this need by examining the nuclearity of the chloroaluminate ions and their interactions with reaction intermediates.

Although depolymerization methods for various commodity plastics and several engineering plastics have been developed, such methods for robust super engineering plastics that have very high heat and chemical resistance are nearly unexplored. Here, the authors report the catalytic depolymerization-like chemical decomposition of oxyphenylene-based super engineering plastics such as polyetheretherketone, polysulfone, and polyetherimide using thiols via selective carbon–oxygen main chain cleavage to form monomer-type molecules, namely electron-deficient arenes with sulfur functional groups and bisphenols.

Polyetheretherketone (PEEK) is an important super engineering plastic utilized in industries owing to its thermal stability and mechanical strength, however, its robustness hinders chemical recycling. Here, the authors report the depolymerization of insoluble PEEK using sulfur nucleophiles via carbon–oxygen bond cleavage and then treatment with organic halides to form various dithiofunctionalized benzophenones and hydroquinone monomers.

Plastic upcycling to value-added products is of great interests. Here the authors investigate a nickel-cobalt phosphide electrocatalyst for electroreforming of polyethylene terephthalate plastic toward valuable potassium diformate, terephthalic acid, and H₂ fuel.

The development of robust catalysts that could work under industrial-scale current densities bring promise but also a challenge for hydrogen production. Here, the authors report an in situ activation method to produce ferromagnetic ruthenium clusters that can catalyze the hydrogen evolution reaction at high current densities.

The increasing production of lithium-ion batteries and plastics presents significant challenges to resource sustainability and ecosystem integrity. This study highlights the utilization of spent lithium cobalt oxide cathodes as photothermal catalysts to transform various waste polyesters into valuable monomers.

Chemical recycling of plastic enables renewed production of pristine materials, but generally comes at a high energy cost. This review focuses on light-driven approaches for chemically recycling and upcycling plastic waste, with emphasis on reduced energy consumption and selective transformations of challenging to recycle backbone structures.

Sustainable recycling of waste plastics is of highly strategic significance. Here, the authors report a photothermal recycling system for transforming polyolefin plastics into high-selectivity liquid fuels through the synergistic utilization of ultraviolet, visible, and near-infrared irradiation.

There is a real need to create materials capable of plastic recycling and upcycling. Here, the authors report a heterogeneous carbon nitride photocatalyst which efficiently converts polystyrene plastics into aromatic oxygenates, such as benzoic acid.