Transforming Plastic Waste into Hydrogen and Nanocarbon: A Sustainable Path to Clean Energy and a Circular Economy

Plastic waste production, coupled with inadequate recycling rates, has reached alarming levels and presents a significant environmental challenge, prompting the need for sustainable strategies to mitigate its adverse impact. Thermochemical transformation of carbon-rich waste materials, like plastics, emerges as a promising option and a viable avenue to extract resources in contrast to conventional waste management methods like incineration and landfilling. Considerable research has been done to explore the production of fuels and chemicals through catalytic pyrolysis of waste plastic. However, pyrolysis under inert conditions, pyrolysis-dry reforming, pyrolysis-steam reforming, and pyrolysis-oxidative steam reforming to produce hydrogen from plastic waste have received comparatively little attention. Hydrogen production is intricately linked to the feed chosen and the selection and optimization of catalysts, reactor design, and process conditions to enhance yield and selectivity. Similarly, the type of metal, the support utilized for catalyst synthesis, and their interaction significantly influence carbon deposition over the catalyst surface upon hydrocarbon degradation. This review underscores the dual benefits of addressing plastic waste treatment and advancing the hydrogen economy while simultaneously producing high-value nanocarbon materials. By integrating insights from recent studies, this work provides a comprehensive understanding of the catalytic thermochemical pathways for plastic waste valorization, offering guidance for future research and industrial applications. By summarizing current advancements in this area and considering the growing concerns related to waste management and climate change, the prospect of utilizing waste to sustainably produce clean energy is compelling and calls for further in-depth research.