What to do with polyurethane waste? The environmental potential of chemically recycling polyurethane rigid foam†

Abstract

Chemical recycling of plastics has gathered momentum to manage plastic waste and replace fossil-based feedstocks. However, chemical recycling of complex polymers, such as polyurethane (PU) rigid foam, can yield a variety of intermediates. But which intermediates reduce environmental impacts the most when produced from PU is currently unclear. In this work, we assess the potential of chemical recycling of PU rigid foam waste to reduce environmental impacts compared to state-of-the-art treatment options, such as incineration and landfilling. For this purpose, we extend the environmental potential methodology to account for any possible recycling product. We then calculate the environmental potential for six ideal closed-loop recycling options and one experimentally demonstrated recycling option based on a patent. All analyzed chemical recycling options for PU rigid foam to various intermediates are shown to offer a substantial environmental potential to reduce multiple environmental impacts. The best performing option recovers both polyol and isocyanate and can decrease climate change impacts by 3.8–5.6 kg_CO2eq. per kg PU treated. However, PU rigid foam recycling to low-value intermediates, such as benzene, does not seem promising due to burden shifting actually increasing half of the analyzed environmental impacts. We further determine the minimal conversion rates required to reduce environmental impacts by chemical recycling of PU rigid foam. Our environmental potential analysis assists the decision-making process for product prioritization in recycling and identifies (side-)products whose recovery is worth investigating from an environmental perspective.