Chemical Recycling of Waste Polyurethane Foams: Efficient Acidolysis under the Catalysis of Zinc Acetate

Acidolysis is an efficient chemical degradation method that could completely depolymerize thermosetting polyurethanes into reusable monomers. However, energy consumption control and the quality improvement of recycled products remain significant challenges. Herein, zinc acetate is discovered as a high-performance catalyst, which promotes the rapid and efficient acidolysis of polyurethane foams (PUFs) and also helps realize a solvent-free reaction and significantly improves the quality of repolymerizable recovered polyols (RPs). In acidolysis, zinc ions could attract the oxygen on the carbonyl group from urea and carbamate bonds. Meanwhile, acetate activates the acidolysis agent and promotes faster and more thorough degradation of PUFs, with a high degradation degree (97%) and fast rate (3 h at 200 °C). The recycled polyols could be used as a partial substitute for virgin polyol (up to 40 wt %) in the reproduction of flexible PUFs (RPUFs), with mechanical properties of RPUFs still meeting the commercial requirements. This research presents an efficient acidolysis with a high-performance catalyst, which promoted the development of the technology for PUF degradation and recycling, realizing a green, energy-saving reaction, high-value utilization of RP, and providing theoretical support for industrialization.