Selective Degradation of Polyurethanes in Mixed Plastic Wastes via Ir-Catalyzed Hydrogenolysis

From ocean pollution to carbon emissions, mixed plastics are an environmental headache. The group of Yuto Yamada (The University of Tokyo), Professor Takanori Iwasaki (Kyushu University), Shinji Tanaka (National Institute of Advanced Industrial Science and Technology), and Professor Kyoko Nozaki (The University of Tokyo) has now developed a catalyst that selectively degrades polyurethane in mixed plastic waste while leaving coexisting polyester and polyamide intact. Using an iridium-based catalyst with a phenolate salt additive and hydrogen gas, the method was successfully tested on blended textiles and end-of-life car seats, offering a practical route to recycling complex plastic combinations long considered too difficult to separate.

Mixed plastic waste often contains polyurethane tangled together with polyester, polyamide, etc. and these materials normally have to be separated before recycling can happen. Using a new catalyst and hydrogen gas, the polyurethane is selectively broken down into small, reusable molecules, which were then easily separated from the intact polyester and nylon by simple filtration. 

Papers 
Journal: Angewandte Chemie International Edition 
Title: Selective Degradation of Polyurethanes in Mixed Plastic Wastes via Ir-Catalyzed Hydrogenolysis
Authors: Yuto Yamada, Takanori Iwasaki, Shinji Tanaka, and Kyoko Nozaki
DOI: 10.1002/anie.4288189

Reference

Kyusyu University: https://www.kyushu-u.ac.jp/en/researches/view/411