Catalytic methane decomposition (CMD) is a promising method for producing clean hydrogen while simultaneously generating solid carbon, offering an environmentally friendly alternative to conventional hydrogen production by eliminating CO₂ emissions. This study explores the use of heat-treated woody biochar derived from poplar, red pine, and bark as a sustainable catalyst to replace conventional metal-based options, which often suffer from deactivation issues. Experiments were conducted at 600, 800, and 1000 °C to assess the effects of surface functional groups, acidity, and physicochemical characteristics on catalytic performance. Among the tested samples, heat-treated poplar biochar exhibited the highest methane conversion (~50%) at 1000 °C, despite its lowest surface area (215.1 m²/g), due to its superior surface acidity (0.38 mmol/g). The conversion trend followed: HT poplar > HT red pine > HT bark, with initial CH₄ conversion rates of approximately 50%, 35%, and 25%, respectively. These results highlight the dominant role of surface acidity over surface area in CMD performance. Additionally, the near-zero H:C and O:C ratios observed in both pre- and post-reaction biochar samples emphasize their carbon sequestration potential. The findings confirm the catalytic capability of biochar in CMD and suggest that further tuning of surface chemistry could enhance performance at lower temperatures, improving overall energy efficiency. Moreover, valorizing the carbon co-product in accordance with ASTM standards can support a circular, scalable, and climate-resilient hydrogen production system.
