Lanthanide photocatalysts for polymer upcycling

Once called "the material of a thousand uses owing to its durability and versatility, the chemical properties of plastic that enable it to withstand degradation cause its disposal to be challenging. Among the various known types of plastic, polyvinyl chloride (PVC) and polystyrene (PS) are found everywhere from packaging to electronics. PVC is the second-largest manufactured resin in the world contributing to ~12% of the total demand for plastics. That equates to 55 million tons of PVC produced in 2013, and a predicted annual production of up to 59.72 million tons by 2030. With most PVC products now reaching the end of their usable life, PVC degradation represents a timely environmental challenge. In addition, many PVC-based products contain various additives such as plasticizers, which pose a risk to humans and the environment due to their hormone-like activity. Polystyrene (PS) is primarily employed for consumer product protection, CD cases, and food packaging. Despite its widespread use, the recycling rate for PS is less than 10%. Traditional PS recycling methods involve mechanical or chemical processes that downgrade the material. Currently, thermal processes like pyrolysis represent the most frequently used approach to convert PS into high-value chemicals. However, thermal processes are energy intensive. Hence, new, less energy intensive ways are urgently required to convert PVC and PS into materials with added value allowing the upcycled material to be used indefinitely. In the present project, we use special catalysts made from cheap, non-toxic rare-earth metals to harvest light energy, as part of a process called photocatalysis, for energetically less intensive upcycling of PVC and PS. Instead of degrading PVC, we aim to chemically modify the polymer making it less toxic and therefore genuinely upcycled. Since harsher chemical conditions are generally required to upcycle PS rendering PS upcycling using currently available rare-earth catalysts challenging, we will focus on the development of new more stable photocatalysts that withstand the generally harsher conditions of PS upcycling. This project is groundbreaking because it is the first time anyone has attempted to use these specific catalysts for this purpose. The insights gained during this project could revolutionize plastics recycling and improve our understanding of how rare earth metals can be used in photocatalysis.