Plastic pyrolysis review: sustainable energy and hydrogen production from waste PE, PET, PP, PVC, and PS

The global annual production of waste plastics has reached approximately 370 million tons, while only 9% is recycled. Their slow natural decomposition makes plastic waste management a critical environmental challenge. Meanwhile, increasing industrialization and urbanization have intensified global fuel demand, highlighting the need for sustainable alternatives to fossil fuels. In this context, converting waste plastics into valuable energy products has emerged as a promising approach. Pyrolysis is a thermochemical process that converts waste plastics into liquid oil, gas, char, and wax, with liquid oil being the most commercially significant product. This review examines the potential of pyrolysis for energy recovery and hydrogen production, with hydrogen considered a clean and sustainable energy carrier. Competitive recycling methods are also discussed to provide a broader perspective on current waste plastic conversion technologies. Key aspects include process optimization, product characteristics and utilization, and the advantages and limitations of pyrolysis. Particular attention is given to factors influencing product distribution and hydrogen generation. By identifying major opportunities, challenges, and research gaps, this review provides directions for future research. Overall, plastic pyrolysis offers a promising route for effective waste management and sustainable energy production.