New catalyst-free process turns waste plastic into useful diacids with water and oxygen, cutting carbon emissions

Researchers from Zhejiang University, the University of Tokyo, and Cardiff University have developed a catalyst-free method to convert hard-to-recycle plastics like polyethylene, rubber, and dirty mixed waste into valuable diacids such as succinic acid. The process uses only water, oxygen, and heat at around 125 degrees Celsius, with reactions occurring on the surface of tiny water microdroplets. A life-cycle assessment shows the method achieves a net reduction of about 0.30 kg of CO₂ per kilogram of plastic, comparable to mechanical recycling but without the need for clean, sorted waste. The process works on common plastics, old tires, and metal-lined packaging, and has been scaled up to 300 grams in a 5-liter reactor. A techno-economic analysis suggests a medium-sized plant costing about $144 million could earn roughly $72 million annually and pay for itself in three years without subsidies. The method avoids catalyst poisoning issues that plague other chemical recycling approaches, making it practical for mixed and contaminated waste streams that are normally landfilled or incinerated.