Heterogeneous catalysis for the closed-loop chemical recycling and regeneration of flexible polyurethane foam materials

Flexible polyurethane foams (PUFs), widely used in long-lasting applications such as automotive seating, pose significant environmental challenges at the end of their life due to their complex chemical structure, which cannot be broken down by physical or mechanical recycling methods. These approaches afford low-value product with limited applications and may generate toxic by-products. In contrast, chemical recycling offers a promising route to recover polyurethane monomers through the depolymerization of urethane, ester, and ether linkages. Among the different chemical recycling methods, glycolysis has attracted particular attention because it combines industrial scalability with the ability to produce high yields of reusable polyols under mild conditions. In this study, a novel microwave (MW)-assisted glycolysis method is proposed as an alternative to conventional processes. Traditional glycolysis often requires elevated temperature and long reaction times. The novelty lies in the use of a heterogeneous catalyst in bead form, consisting of iron oxide supported on γ-alumina. This catalyst improves depolymerization efficiency and promotes the formation of high-purity polyols. Unlike homogeneous catalysts, it reduces the environmental impact. It also allows simple recovery and reuse, overcoming a key limitation of conventional glycolysis. In this work, heterogeneous catalysis enabled the efficient glycolysis of flexible PUFs at 200 °C and 20 bar, with 2% (by weight) catalyst dose and polyethylene glycol 400 (PEG 400) as the glycol. The glycolyzed product is comprehensively characterized to evaluate its chemical structure, functionality, and suitability for reuse in recycled PUF formulations. It has been subsequently employed in the preparation of flexible PUFs. The resulting foams exhibited viscoelastic properties closely resembled with reference foam, confirming the effectiveness and reliability of the proposed method. These results demonstrate that heterogeneous catalysis can serve as a sustainable recycling strategy, transforming end-of-life polyurethane foams into high-value, reusable feedstocks and supporting a circular lifecycle.