Catalytic Upcycling of Waste Plastics by Induction Heating

The development of plastics over the past half century has led to rapid technological advances; however, the long-term negative environmental impacts of these materials compel new depolymerization and upcycling strategies. Plastics are indispensable due to their unique physical and chemical properties and affordability, leading to a significant increase in production rates. However, their recycling rates lag far behind their production rates. Polyolefins like LDPE and HDPE, which are common plastics, decompose very slowly in the environment. Converting these plastics into useful products often requires high-temperature pyrolysis, resulting in undesired distributions of products.\nTo address this challenge, this study focuses on converting plastic waste into useful monomers and oligomers using specially designed catalysts suitable for Radio Frequency (RF)-based heating reactions. Currently, most studies in plastic recycling employ the use of conventional thermal heating. RF-IH depolymerization offers several benefits over traditional thermal catalysis, in particular, a large interface/bulk temperature gradient and the inhibition of some secondary reactions.\nInitial experiments used various catalysts such as metal oxides, zeolite-supported Pt/Ni, and an RF susceptor (Fe3O4) in batch reactors to depolymerize polyolefins. Results demonstrated up to 95% conversion of LDPE with minimal formation of aromatics, coke, or methane that are typically observed with thermal heating. Moreover, integrating RF-IH heating with zeolite-based catalysts in a continuous reactor setup shows promise for long-term catalyst effectiveness in polyolefin depolymerization. This approach underscores the critical role of catalyst selection and operational parameters in enhancing efficiency and product quality associated with plastic recycling.