Catalytic pyrolysis of plastic waste for hydrogen and carbon nanoparticle production: A pathway to sustainable biofuels and circular economy

• Mixed plastic waste converted into hydrogen and carbon nanoparticles via pyrolysis. • Key parameters: reaction time (30–50 mins), temperature (400–500 °C), catalyst type. • Higher temperatures (600–800 °C) boosted hydrogen yield; longer times raised efficiency. • Ni/SiO 2 catalyst excelled, achieving 43.2 % hydrogen efficiency and 34.7 g nanoparticles. • Hybrid catalysts surpassed non-catalysts, aiding waste management and clean energy. This study explores a sustainable solution to waste plastics and environmental pollution by converting such waste plastics of various kinds (mixed plastic waste) into hydrogen (H 2 ) to produce clean energy and carbon nanoparticles for various applications. Mixed plastic waste, such as milk pouches, crushed plastic bottles, and used wrappers, was processed through pyrolysis followed by gasification at high temperatures. The significant pyrolysis process parameters such as reaction time (30 min, 40 min, and 50 min), temperature (400 °C, 450 °C, and 500 °C), and catalyst type (Ni/SiO 2 , Co/SiO 2 , and Ni/Mg) were considered to optimize yield of H 2 and carbon nanoparticles production. Results showed that raising the temperature from 400 °C, to 500 °C °C significantly increased H 2 yield, while longer reaction times increased methane (CH 4 ) and hydrogen (H 2 ) concentrations, reducing carbon monoxide (CO) and carbon dioxide (CO 2 ). The Ni/SiO 2 catalyst delivered the best results, achieving the highest H 2 conversion efficiency of 43.2 % and maximum nanoparticle production (34.7 g). Hybrid catalysts consistently outperformed non-catalyst conditions, yielding more H 2 and nanoparticles. This approach not only manages plastic waste but also contributes to clean energy and carbon materials, showcasing a practical, eco-friendly path for addressing environmental challenges.