Facile modification of cobalt ferrite by SiO 2 and H‐ZSM‐5 support for hydrogen and filamentous carbon production from methane decomposition

In this work, new catalyst composed of cobalt ferrite CoFe2O4 supported on amorphous silica (SiO2) and zeolite (H-ZSM-5) were prepared using impregnation method with loading ratio 1:1. The catalytic activity of the new 50 wt% CoFe2O4/SiO2 and 50 wt% CoFe2O4/H-ZSM-5 catalysts were evaluated for direct methane decomposition to hydrogen production at fixed operating temperature of 800°C. The physiochemical properties of the fresh and spent catalysts were characterized by several techniques such as scanning electron microscope (SEM), X-ray diffractometer (XRD), Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy (XPS), thermogravimetric (TGA), and Raman spectroscopy. The CoFe2O4/H-ZSM-5 catalyst exhibited higher activity and stability than CoFe2O4/SiO2 catalyst. Maximum methane conversion reached 37.35% and hydrogen formation rate of 76.48 × 10−5 mol H2 g−1 min−1 at time on stream (TOS) of 300 min for CoFe2O4/H-ZSM-5, while its 5.80% with 15.82 × 10−5 mol H2 g−1 min−1 at TOS of 30 min. The XRD, Raman, and XPS results confirm the presence of CoFe2O4 particles on the CoFe2O4/H-ZSM-5 catalyst surface, while the CoFe2O4 particles partially shield with SiO2 in CoFe2O4/SiO2 catalyst. SEM images of spent catalysts elucidated the formation of filamentous carbon which indirectly confirm the higher distribution of CoFe2O4 in CoFe2O4/H-ZSM-5 than that of CoFe2O4/SiO2. The deposited carbon on spent CoFe2O4/H-ZSM-5 catalyst was evaluated using TGA, which was found to be ca. 50 wt%. Highlights CoFe2O4/SiO2 and CoFe2O4/H-ZSM-5 catalysts synthesized and characterized by various techniques. H-ZSM-5 and SiO2 support material were found strongly affects the physiochemical properties and the methane decomposition activity of CoFe2O4 catalyst. CoFe2O4/H-ZSM-5 catalyst performance reached 37.4% and the hydrogen formation rate was 76.5 × 10−5 mol H2 g−1 min−1. CoFe2O4/SiO2 catalyst demonstrated a negligible activity toward methane cracking and producing hydrogen. The estimated deposited carbon on the spent catalysts were 1 wt% and 50 wt% for CoFe2O4/SiO2 and CoFe2O4/H-ZSM-5, respectively.