Microwave Catalytic Co-Upcycling of Polyethylene and Polystyrene

Abstract

Microwave-assisted catalytic upcycling plastic wastes into valuable chemicals is a promising technology to treat plastic wastes. In this study, the catalytic upcycling of low-density polyethylene (LDPE), polystyrene (PS), and their mixture under microwave (MW) irradiation was explored. In comparison to conventional thermal conditions, MW heating produced significantly more BTX and achieved better conversion due to the “hotspots” formation over a catalyst. MW irradiation also lowered the activation energy for the catalytic pyrolysis of pure and mixed plastics. For mixed plastics, the E a was reduced to 20.3 kJ/mol at MW conditions compared to 38.3 kJ/mol in conventional thermal heating. The synergistic mechanism between LDPE and PS for BTX production was proposed, in which aromatization occurred within the HZSM-5 channel and the presence of LDPE inhibited coking while PS provided the backbone for BTX formation.