Assessing the environmental benefits of textile waste valorization via methanolysis

The increase in textile production and disposal has contributed to the accumulation of textile waste in the environment. Identifying sustainable methods to valorize PET textile waste can help reduce the environmental impacts associated with this waste stream. Methanolysis is a chemical recycling method that enables the depolymerization of PET textiles into their constituent monomers, dimethyl terephthalate (DMT) and ethylene glycol (EG), which can then be used to produce PET again or for other applications. Assessing the environmental benefits of methanolysis over fossil-based production of these monomers is essential for deploying this technology. In this work, we propose a computational framework that integrates process modeling and life cycle assessment (LCA) to evaluate the benefits of producing PET monomers via methanolysis over their production from fossil sources. We analyze two methanolysis process variants (subcritical and vapor phase), considering a mass allocation scenario and a combined mass scenario, evaluating the climate change, energy or resource use, and water use metrics. Our results reveal that the subcritical and vapor phase processes can provide environmental benefits over the fossil-based production of DMT and EG, but the benefits vary depending on the scenario and the metric evaluated. Overall, both process variants can achieve lower or similar impacts to the fossil-based alternative when the combined mass scenario is considered. Our analysis also provides insights into which components of the methanolysis processes drive the total impacts.