Hydrogen production from plastics: A comprehensive review of thermochemical pathways, process optimization and sustainability insights

Plastic waste accumulation has become a major environmental challenge, prompting interest in advanced recycling technologies that can recover value from non-recyclable streams. Among these, thermochemical processes for hydrogen production offer a compelling route for both waste management of heavily contaminated streams and clean energy generation. This review provides a comprehensive overview of hydrogen production from plastic waste through catalytic gasification, pyrolysis-reforming, and pyrolysis-chemical vapor deposition. Following an overview of these thermochemical routes, the review examines how process parameters - such as plastic feedstock, catalyst type, reactor configuration, temperature, and oxidant input- affect hydrogen yield and co-product formation. Further, environmental and techno-economic assessments are discussed to evaluate the feasibility and scalability of each approach. By consolidating current advances and identifying key research gaps, this work aims to guide future developments toward viable and sustainable hydrogen production from plastic waste.