Vapor-Phase Dicarboxylic Acids and Anhydrides Drive Depolymerization of Polyurethanes.

Area of Science:

• Materials Science
• Chemical Engineering
• Green Chemistry

Background:

• Polyurethane (PU) is a widely used plastic, but its thermoset nature poses recycling challenges.
• Chemical recycling, specifically acidolysis, offers a pathway to recover valuable polyol monomers from PU waste.
• Existing acidolysis methods require high temperatures and result in complex separations and byproducts.

Purpose of the Study:

• To develop a more efficient and environmentally friendly method for chemical recycling of postconsumer polyurethane waste.
• To investigate the use of dicarboxylic acid (DCA) in vapor phase for selective polyurethane acidolysis.
• To overcome limitations of traditional high-temperature liquid-phase acidolysis.

Main Methods:

• Selective acidolysis of polyurethane using dicarboxylic acid (DCA) in vapor form.
• Conducting reactions at temperatures below the melting points of DCAs (<150 °C).
• Application of the methodology to commercial polyurethane foam (PUF) postconsumer waste.

Main Results:

• Successful recovery of polyol from PU waste using DCA vapor at reduced temperatures.
• Demonstrated adherence to green chemistry principles, minimizing unwanted byproducts.
• Prevention of polyol esterification, eliminating the need for additional hydrolysis steps.

Conclusions:

• Vapor-phase acidolysis with DCA is a viable and greener alternative for polyurethane recycling.
• The method offers improved efficiency, lower energy consumption, and simplified product separation.
• This approach facilitates closed-loop recycling of postconsumer polyurethane materials.