Japanese Researchers Develop Process to Convert Polyesters Into New Products

Oct. 10, 2023
Team says process is less wasteful and more cost effective than traditional recycling methods.

Tokyo Metropolitan University researchers have developed a new chemical process that converts polyesters to morpholine amide, a building block for synthesizing various compounds. 

Recycling polyesters, including polyethylene terephthalate (PET) in plastic bottles, often requires power to get the required chemical reactions hot enough, or strong alkaline conditions, which generate chemical waste. The process creates intermediate compounds that are used to make the same products they came from, the research team says. This process is wasteful and costly, the research team says.

Scientists at Tokyo Metropolitan University have been working to break this “closed loop” and create compounds from plastic waste.

The team, led by Associate Professor Yohei Ogiwara and Professor Kotohiro Nomura from Tokyo Metropolitan University, used a inexpensive solvent called morpholine and a small amount of a titanium-based catalyst to turn polyesters into morpholine amides. They can be converted into intermediate compounds for making more polyester, and can be reacted to make ketones, aldehydes and amines to produce additional compounds.

The new process doesn’t require expensive reagents or harsh conditions and is nearly free of chemical waste. The researchers also say it results in high yields, and any unreacted solvent can be easily collected. The team also found that only a small amount of catalyst was required to drive the reaction at a sensible speed, while all that is needed to separate the product is simple filtration. The main reaction occurs at normal pressure, meaning no special reaction vessels or devices are required, enabling scalability. The team demonstrated this by taking 50g of PET material taken from an actual PET beverage bottle and reacting it with morpholine, getting more than 70 grams of morpholine amide, a yield of 90%.

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