Synthesis of COx-free hydrogen via natural gas decomposition over titanium dioxide-supported bimetallic catalysts

Nickel and cobalt-based titania-supported bimetallic catalysts were synthesized using the co-precipitation technique. The total metal loading varied between 20 and 60 wt% while keeping nickel to cobalt ratio of unity. In comparison with low-loading catalysts i.e., 10 and 15 wt% each of nickel and cobalt supported over titania (10NCT and 15NCT), high-loading catalysts (20NCT, 25NCT, and 30NCT) have shown higher activity and stability performances. Among the high-loading catalysts, 25NCT catalyst outperformed the rest of the catalysts with the highest methane conversion and carbon yield. The higher specific surface area (115.1 m²/g), evaluated from physisorption, facilitates better metal particle dispersion; suitable metal-support interaction, and number of reducible species determined by temperature-programmed reduction, have played a vital role in enhanced activity of 25NCT. The morphological analysis revealed the formation of carbon nanotubes via following both tip-growth and base-growth mechanisms.