Hydrogen production via thermocatalytic decomposition of methane using carbon-based catalysts

Abstract

Thermocatalytic decomposition (TCD) of methane is one of the most effective methods for pure hydrogen production. Catalysts were selected for TCD of methane in this study to utilize biochar as a catalyst. Among these catalysts, two catalysts (named activated biochar (AB) and heat-treated biochar (HB)) were prepared from Douglas fir, whereas the other four were prepared using commercial activated carbon and zeolite with and without doping ruthenium metal. The catalysts were characterized using XRD, SEM imaging, TEM, H₂-TPR, and BET specific surface area and pore size analysis. The Ru doped commercial activated carbon catalyst (Ru–AC) was deactivated continuously during a 60 h reaction run, whereas AB exhibited comparatively stable methane conversion up to 60 h. The methane conversion was 21% for Ru–AC and 51% for AB after 60 h of reaction time at 800 °C. The very high surface area of AB (∼3250 m² g⁻¹) and its microporosity compared to other catalysts could have resulted in resistance against rapid deactivation. Furthermore, carbon nanotube by-products were observed in TEM images of solid residues that could form due to the presence of alkali metals in the biochar. Carbon nanotube formation could contribute significantly to the extended life of AB.