Abstract NiFe2O4/H-ZSM-5 and NiFe2O4/SiO2 catalysts were prepared via co-precipitation method followed by physical mixing with a 1:1 loading ratio. Their catalytic performance for direct methane decomposition was evaluated under fixed temperature and gas flow rate conditions. The morphology, texture, and structural properties of the supported NiFe2O4 catalysts were investigated using Field emission-scanning electron microscope (FE-SEM), X-ray diffraction (XRD), N₂ adsorption–desorption (BET), and Hydrogen temperature-programmed reduction (H2-TPR) techniques. The results revealed that NiFe2O4 exhibited a spinel phase with a mesoporous structure and was uniformly distributed over both supports. H2-TPR analysis confirmed the formation of Ni and Ni–Fe metallic phases as active components in NiFe2O4/H-ZSM-5, whereas NiFe2O4/SiO2 was reduced predominantly to a Ni–Fe alloy. The NiFe2O4/H-ZSM-5 catalyst exhibited earlier catalytic activity, reaching a CH4 conversion of 40.6% after 120 min, while NiFe2O4/SiO2 demonstrated higher stability, achieving 40% CH4 conversion after 300 min. Filamentous carbon was formed as a by-product of methane decomposition and was uniformly deposited on the spent catalysts, as observed by FE-SEM images. The carbon content, evaluated by thermogravimetric analysis (TGA), was 23 wt% for NiFe2O4/SiO2 and 52 wt% for NiFe2O4/H-ZSM-5.
Abdulrahman I. Alharthi (Fri,) studied this question.