Effect of acid catalysts on yield and selectivity of plastics waste pyrolysis from municipal solid waste in Samui Island, Thailand

• Pyrolysis is performed to convert plastic waste into liquid fuel using catalytic reactions. • Temperatures were set at 425 °C, 450 °C, and 475 °C, different amounts of catalyst loading (0, 1, 3, 5 wt.%), and different types of catalysts (HY zeolite, NaY zeolite, spent fluid catalytic cracking (FCC). • The pyrolysis at 450 °C with 3 wt.% of spent FCC catalyst provided the highest amount of liquid product. • The pyrolysis of polystyrene (PS) produced the most liquid product (91.44 wt.%), while the liquid products from the pyrolysis of polyethylene (PE) exhibited the highest percentage of diesel (36.60 wt.%). Due to concerns about plastic waste affecting solid waste management, pyrolysis has emerged as an intriguing technology that enhances sustainability potential by reducing harmful plastic waste in ecosystems and natural resource usage as well as generating profits from its products as an alternative fuel for engines. In this study, Samui Island plastic waste was used as feedstock for pyrolysis. The process was carried out at different temperatures (425 °C, 450 °C, and 475 °C), different amounts of catalyst loading (0, 1, 3, 5 wt.%), and different types of catalysts (HY zeolite, NaY zeolite, spent fluid catalytic cracking (FCC), and Fe/Al 2 O 3 ). The results showed that the pyrolysis at 450 °C with 3 wt.% of spent FCC catalyst provided the highest amount of liquid product. In addition, the pyrolysis of polystyrene (PS) produced the most liquid product (91.44 wt.%), while the liquid products from the pyrolysis of polyethylene (PE) exhibited the highest percentage of diesel (36.60 wt.%). After improving product yield from a mixture of PE/polypropylene (PP)/PS (80:15:5), a representative sample of plastic waste from Samui Island, the results demonstrated that the pyro-diesel was comparable to commercial diesel, with a low operating cost (0.33 USD/L) and improved pyrolysis oil quality (0.65 USD/L).