Technology Molecular recycling Understanding material-to-material methanolysis “Molecular (or chemical) recycling isn’t ready for commercial operation” – or so many people believe. With methanolysis, a specific type of molecular recycling technology, this common misperception couldn’t be further from the truth. Eastman Kodak Company (a forerunner of today’s Eastman) used methanolysis commercially for three decades to recycle photographic and X-ray film. The technology was capable of recycling much more, but until the last few years, the demand for recycled content was missing. Now that the market is alive and growing, methanolysis has an important role to play in shaping a more sustainable materials industry – if stakeholders across the value chains work in tandem to create a robust recycling ecosystem. Renewing polyester waste for high-value uses Polyester products that can’t be mechanically recycled are destined to wind up in a landfill or incinerator (or, worst of all, out in the environment). Those end-of-life options abruptly end the potentially infinite useful life of the polyester molecules. Enter methanolysis – a molecular recycling technology that makes new materials out of polyester plastic waste that has been diverted from landfills and incinerators. Mechanical recycling chops and shreds plastic; only altering its physical form and causing some quality degradation. Methanolysis, on the other hand, uses a process called depolymerization. By heating the polyester waste plastic and treating it with methanol, it unzips the polyesters and converts them back to their molecular building blocks, dimethyl terephthalate (DMT) and ethylene glycol (EG). Colours and additives are removed in the process. The molecules that result from methanolysis are indistinguishable from materials made with virgin content. Eastman uses those pure DMT and EG molecules to make new materials – not fuel or energy. They are ideal for making specialty copolyesters that go into packaging and durable medical, beauty, and electronic applications, among others. Eastman also sees the potential for using molecular recycled content in food-grade PET packaging. Methanolysis feedstock: big challenge, bigger opportunity Mechanical recycling processes are limited to certain types of plastic that can be used in a limited number of end-use applications. Methanolysis processes polyester materials that pose a challenge to mechanical recycling, such as coloured plastic bottles, carpet fibres, films, and even polyesterbased clothing. Eastman ensures that its methanolysis recycling technology does not compete against mechanical recycling for polyester feedstock, but rather complements it. The company follows a three-part feedstock acquisition strategy: 1. Purchase low-value materials, like used PET strapping and rejected plastic waste from conventional mechanical recycling facilities. 2. Forge innovative partnerships to collect and transport hard-to-recycle plastic waste, like carpet and textiles that would not go into the mechanical stream. 3. Create completely new feedstock streams for items such as coloured bottles and thermoform clamshell food packaging that cannot be processed mechanically. Eastman’s single greatest challenge in scaling up methanolysis is accessing enough feedstock when the recycling infrastructure does not yet exist. Material makers like Eastman, consumer packaged goods brands, waste companies, and other stakeholders are partnering to build a supply pipeline to make sure the polyester plastic waste can reach methanolysis recycling facilities. The opportunity is worth the challenge. While mechanical recycling delays the landfilling of plastic, methanolysis enables Eastman to recycle polyester waste over and over again without degradation, keeping those materials out of the landfill and in the value chain. And it does so with a lower carbon footprint compared to virgin, nonrecycled plastic production. The life cycle perspective of methanolysis Recycling technologies that reduce waste yet release more carbon emissions than virgin production are not an acceptable solution. True solutions must operate at the intersection of the plastic waste crisis, climate change, and population growth. Eastman is committed to advancing technologies that reduce environmental impacts and enable a lower-carbon future. To ensure they are making good on that commitment in the realm of molecular recycling, Eastman commissioned a third-party verified life cycle assessment (LCA) of its methanolysis process. The LCA (assessable on Eastman’s website), which was published in early 2022, compares the global warming potential and other environmental indicators of DMT produced via methanolysis (using recycled feedstock) to DMT made using conventional processes (and virgin fossil feedstock). For this cradle-to-gate LCA, the cradle begins at raw material extraction; in the case of plastic waste feeds, this begins at the end of the previous life of the material when it is deemed to be waste. The gate is internal to Eastman at the point where rDMT and rEG (intermediates) are manufactured. Between these two points, the LCA includes raw material acquisition, upstream operations, energy supply and all relevant processing at Eastman. The study used the state-of-the-art Environmental Footprint (EF) impact assessment methodology developed by the European Commission. 68 bioplastics MAGAZINE [04/22] Vol. 17
By: Jason Pierce Senior Technical Leader of Circular Economy Eastman Kingsport, Tennessee, USA Technology The study shows that DMT from methanolysis has significantly lower impacts than conventional DMT in 13 out of the 14 environmental impact categories studied. Most notably, the climate change impact for DMT from methanolysis is 29 % lower. This was calculated by using global warming potential (GWP) characterization factors for all greenhouse gas emissions and expressing the results on the basis of kilograms of carbon dioxide equivalents emitted to the atmosphere. Roughly 73 % less fossil fuel natural resources are used in methanolysis vs. conventional DMT production, and methanolysis also ranks significantly better in terms of water and human health-related impacts. For the sake of conservatism, the study only takes the function of material production into account; if the functional unit of the study were extended to also include avoided plastic waste disposal, the carbon footprint of methanolysis would compare even more favourably due to receiving credit for the avoided landfilling or incineration of plastic waste inputs. As is, the study results clearly demonstrate that recycling polyesters via methanolysis tackles more than the plastic waste crisis – it also addresses climate change. Mechanical recycling remains the least energy-intensive recycling technology, and it is important that clean, clear polyesters that can be mechanically recycled continue to be recycled in this fashion. It is equally important to send difficult-to-recycle polyester waste to methanolysis facilities that can make a substantial difference in the plastic industry’s overall carbon footprint – which is predicted to keep growing even as the world desperately needs to shift to a low-carbon economy. It takes an ecosystem Mechanical recycling and molecular recycling via methanolysis certainly aren’t the only two solutions for tackling the plastic waste crisis and climate change. The world needs an all of the above approach to material-to-material recycling technologies to truly make a difference in these two interconnected issues. Jason Pierce, senior technical leader for Circular Economy and Life Cycle Assessment at Eastman, says, “I see this as an ecosystem of infrastructure and complementary technologies that will be optimized over time”. The ecosystem encompasses the complementary roles of mechanical and molecular recycling, as well as recycling’s relationship to other waste reduction and climate solutions, such as bioplastics. Pierce is also quick to point out that the ecosystem includes much more than the technologies themselves. Collaboration across the value chain and with policymakers is just as important for a robust, future-ready waste reduction ecosystem. It takes brands willing to purchase different types of recycled materials for their products – and then launching take-back programs to get that material back to a recycling facility. It takes partners building new feedstock streams and infrastructure. As a materials manufacturer, Eastman is actively participating in increasing demand and building up supply. The company is currently running pilot methanolysis plants while building two new state-of-the-art methanolysis facilities in the United States and France. The US facility, located at Eastman headquarters in Kingsport, Tennessee, will have a capacity to process more than 100,000 tonnes of polyester plastic waste annually. By as early as 2025, the USD 1 billion plant in France is expected to be capable of processing up to 160,000 tonnes of plastic per year. The facility will include equipment to break mixed-plastic bales and prepare material for processing, a methanolysis unit to break down polyester waste plastic into DMT and EG, and a unit to purify and repolymerize the chemicals into Eastman’s branded polymers for use in packaging, textiles, and other products. www.eastman.com Understanding mass balance Molecular recycled and virgin materials are indistinguishable. Mass balance is an accounting system used to track the recycled content through complex manufacturing processes. This vetted and standardized system is used in a variety of industries. It is analogous to how power companies account for the sale of renewable energy to consumers using an electric grid. It’s also how some brands certify the amount of sustainably sourced cocoa in their products. bioplastics MAGAZINE [04/22] Vol. 17 69
