Professor Kotohiro Nomura’s research group at Tokyo Metropolitan University has developed an efficient method for the exclusive depolymerization of PET (polyethylene terephthalate)*1, PET bottles and textile wastes, using alcohols and an inexpensive, readily available and earth-abundant iron catalyst. This method can provide a new possibility for the selective chemical conversion of polyesters, an important key technology for circular economy.
Plastic waste has been a serious environmental problem that needs to be resolved urgently. However, the current situation is that most of it is reused as fuel and the percentage of material reused is still low. Polyester*2, which is formed by repeated “ester bonds” created by the reaction of a carboxylic acid and an alcohol—particularly PET—has been a commodity plastic widely used for bottles, textiles, carpets, curtains, etc. PET bottles have been recycled mostly by material recycling (collection, sorting, reuse), but the quality of the recycle resin is generally inferior to the virgin resin. Therefore, the importance of developing a "chemical recycling*3" method that cuts the ester bonds and efficiently returns them to chemical raw materials has been recognized recently. However, the conventional methods require high temperatures and large amounts of acid and/or inorganic/organic base. Therefore, a simple, inexpensive, and environmentally friendly method has been desired.
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