Steam reforming of glycerol for co-producing hydrogen and carbon nanotubes over nanoscale Ni-based catalysts: Insights into support effect and carbon deposition

Glycerol, a major byproduct of biodiesel production, is commonly used as an inexpensive feedstock for hydrogen (H₂) production through catalytic reforming. Developing efficient Ni-based catalysts with appropriate supports remains a challenge. In this study, three Ni-based catalysts, each containing 10 wt% Ni with different supports: carbon nanofibers (Ni@CNF), activated carbon (Ni/AC), and alumina (Ni/γ-Al₂O₃), were comparatively evaluated for their effectiveness in the catalytic steam reforming of glycerol. The results show that both the catalyst support and the reforming temperature influence the co-production of H₂ and carbon nanotubes. All three catalysts exhibit good catalytic performance of H₂ production at 700 °C for 1 h. The corresponding H₂ yields, based on a steam-glycerol molar ratio of 11.9 and a flow rate of 0.2 mL/min, are 86.5%, 81.3%, and 69.2% for Ni@CNF, Ni/AC, and Ni/Al₂O₃, respectively. Ni@CNF demonstrates high H₂ production and good catalytic stability, whereas Ni/Al₂O₃ generates high-yield carbon nanotubes.