【Frontiers in HaiChuan Chemical Technology】The Institute of Physics and Chemistry, Chinese Academy of Sciences proposes using photo-reforming of waste PET plastic to produce formamide

Thread Content

Polyethylene terephthalate (PET), as an important thermoplastic polyester, has an annual global production volume of over 70 million tons, and is widely used in areas such as everyday food packaging and textiles. However, behind such large production volumes, about 80% of the discarded PET is dumped or landfilled carelessly, causing severe environmental pollution and leading to a significant waste of carbon resources. How to achieve the recycling of waste PET has become a key challenge that needs to be addressed urgently for global sustainable development. Among existing recycling technologies, photo-reforming technology has attracted considerable attention due to its green and mild properties. This technology uses clean and pollution-free solar energy as a driving force to generate active redox species in situ under normal temperature and pressure, thereby facilitating the conversion of waste plastics and their upgrading into higher-value products. However, at present, photo-reforming products are mostly limited to simple oxygen-containing compounds such as formic acid and glycolic acid. Recently, a team led by Researcher Chen Yong from the Center for Photochemical Conversion and Synthesis at the Institute of Physical Chemistry, Chinese Academy of Sciences, proposed the use of waste PET and ammonia as carbon and nitrogen sources, respectively, to prepare formamide through photocatalytic C-N coupling reactions. To this end, the researchers designed a Pt1Au/TiO2 photocatalyst in which single-atom Pt sites can selectively capture photogenerated electrons, while Au nanoparticles capture photogenerated holes, thereby significantly improving the separation and transfer efficiency of electron-hole pairs and enhancing the photocatalytic activity; the formamide generation rate reached ~7.1 mmol gcat-1 h-1. Experiments such as in-situ infrared and electron paramagnetic resonance have revealed a radical-mediated reaction pathway: photo-generated holes oxidize both ethylene glycol and ammonia to produce aldehyde intermediates and amino radicals (·NH2), which undergo C-N coupling to ultimately yield formamide. This work not only opens up new avenues for the high-value conversion of waste plastics and expands the range of PET-derived upgraded products, but also provides more green, economical, and promising synthetic strategies for the production of important nitrogen-containing compounds such as those used in pharmaceuticals and pesticides. The relevant research findings were published in the journal Angew. Chem. Int. Ed under the title \"Photocatalytic Formamide Synthesis from Plastic Waste and Ammonia via C-N Bond Construction Under Mild Conditions\". The first author of the article is Associate Researcher Liu Fuli from the Institute of Physical Chemistry, while the corresponding authors are Associate Researcher Liu Fuli and Researcher Chen Yong. The research was supported by grants from the **National Natural Science Foundation of China, the China Academy of Sciences-Hong Kong University Joint Laboratory for New Materials, and other funding programs.