Sustainable chemical recycling of low-density polyethylene into light olefins over nano-sized SSZ-13

Abstract

As the demand for sustainable resource utilization increases, chemical recycling of plastic waste is emerging as a promising solution. In this study, we aimed to enhance the yield of light olefins (ethylene, propylene, and butene) from the catalytic decomposition of low-density polyethylene (LDPE) using nano-sized SSZ-13 zeolite. SSZ-13 nanoparticles were synthesized via the dry gel conversion method to increase the surface area and catalytic activity. Compared to commercially available SSZ-13, the synthesized nano-SSZ-13 exhibited a significant improvement in decomposition activity and light olefin yield. The light olefin yield over the nano-sized SSZ-13 was ca. 40%, which is higher than that over commercially available ZSM-5. Surface-specific ion exchange treatments clarified the role of Brønsted acid sites located on the external surface. The catalyst maintained high performance over three consecutive reaction cycles without regeneration, despite the reused catalyst containing coke inside micropores, indicating that the primary active sites are located on the external surface. This study proposes a novel design strategy for controlling product distribution in polyolefin catalytic cracking by tuning the particle size and surface acidity of zeolites.