Earth-Abundant Iron Catalyst Enables Highly Efficient Chemical Recycling of PET and Textile Waste

Plastic waste remains a critical environmental challenge. While collection and reuse programs exist, most plastics are still downcycled or incinerated, and material recovery rates remain low. PET—a polyester widely used in bottles, textiles, carpets, and curtains—is traditionally recycled through mechanical methods, which often yield lower-quality resin. Chemical recycling, which breaks polyester’s ester bonds to recover high-value chemical feedstocks, is increasingly recognized as essential. However, conventional chemical recycling methods are typically costly, energy-intensive, and rely on large amounts of acids or bases.

Professor Nomura's team has addressed these limitations by developing a simple, acid- and base-free depolymerization method. Using iron(III) chloride (FeCl₃) with a trace amount of amine, PET waste can be converted into terephthalic acid diesters—such as dimethyl terephthalate (DMT), diethyl terephthalate (DET), and bis(hydroxyethyl) terephthalate (BHET)—with exceptional selectivity (99.7–99.9% yield), even at scale. The reaction occurs efficiently at mild temperatures of 120–180 °C and allows PET to be selectively depolymerized from mixed waste streams containing cotton and other plastics.

This method provides a highly efficient, environmentally friendly approach for converting PET waste into valuable chemical building blocks, offering new opportunities for sustainable plastic management and the realization of a circular economy.

The research was supported by the Japan Science and Technology Agency (JST) CREST program, under the Research Area “Precise Material Science for Degradation and Stability” and the Research Theme “Development of Bio-Based Advanced Polymers and their Depolymerization, Chemical Recycle.”

Reference:

Youshu Jiang, Kanticha Jaiyen, Mohamed Mehawed Abdellatif, and Kotohiro Nomura, “Quantitative Chemical Conversion of PET Waste Bottles, Textile Wastes by Exclusive Transesterification with Alcohols by FeCl₃–Amine Catalyst Systems,” ACS Sustainable Resource Management, Published online November 12, 2025. doi: 10.1021/acssusresmgt.5c00447