Pyrolysis and Steam Reforming in Series of Footwear Waste to Hydrogen-Rich Syngas and Char for CO2 Adsorption

Footwear manufacturing generates large volumes of heterogeneous polymeric waste. In this context, thermochemical routes offer a pathway to convert this waste into hydrogen-rich syngas and value-added solid products (char). This study presents a proof-of-concept for the integrated valorization of mixed footwear waste via pyrolysis and steam reforming in series for hydrogen production and waste valorization. Footwear waste was pyrolyzed and the resulting volatiles were steam-reformed in a two-stage system, while reforming temperature (700, 800, and 900 °C) and steam-to-carbon ratio (2.5, 7, and 12) were assessed as quantitative factors; hydrogen (H2) yield was adopted as the primary response variable, while CO, CO2, CH4, and light hydrocarbons (C2–C4) were monitored as complementary responses to assess gas quality, and the solid char was characterized in terms of textural properties and CO2 uptake. The highest hydrogen yield, reaching 16.42 mmol g−1, was obtained at a reforming temperature of 900 °C combined with a steam-to-carbon ratio of 7, whereas char produced by pyrolysis at 600 °C exhibited a specific surface area (SBET) of reaching 86.47 m2 g−1 and a CO2 adsorption capacity of reaching 20.13 mg g−1. These findings indicate that pyrolysis coupled with steam reforming can convert footwear waste into a hydrogen-rich gas while simultaneously yielding a char with adsorptive potential, suggesting a feasible route to reduce the environmental impact.