Production of hydrogen-rich syngas and multiwalled carbon nanotubes by biogas decomposition over zirconia supported iron catalysts

A set of Fe/ZrO 2 catalysts were successfully synthesized by a facile urea-assisted solid-state combustion method, and their catalytic test was evaluated for the thermal decomposition of undiluted-biogas into hydrogen-rich syngas and multiwalled carbon nanotubes (MWCNTs). The as-prepared catalysts were characterized by X-Ray diffraction (XRD), Scanning and Transmission electron microscopy (SEM and TEM), Nitrogen-physisorption, X-ray photoelectron spectroscopy and Temperature programmed reduction analyses. The iron was found in the form of hematite and metallic-iron in the fresh and reduced catalysts respectively. A suitable metal-support interaction due to the fine surface dispersion of iron species on ZrO 2 was observed in the catalysts. The N 2 -physisorption analysis indicated the reduced surface area of the catalysts after iron loading. However, it does not influence the catalytic efficiency since the metal amount and metal-support interaction was determined to play the main role. The Fe/ZrO 2 catalysts exhibited improved catalytic efficiency. With increasing the amount of iron and increasing the reaction temperature, the CH 4 and CO 2 conversions were increased significantly. A highest CH 4 and CO 2 conversions of 92% and 89% respectively, with an H 2 /CO ratio of ∼2.25 were obtained for the 50%Fe/ZrO 2 catalyst at 900   °C. The enhanced catalytic performance could be attributed to the fine-surface dispersion of iron-nanocrystals on ZrO 2 . Moreover, the MWCNTs were characterized by XRD, SEM, TEM and Raman analyses for their structural properties.