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

Abstract

In this work, new catalyst composed of cobalt ferrite CoFe 2 O 4 supported on amorphous silica (SiO 2 ) and zeolite (H-ZSM-5) were prepared using impregnation method with loading ratio 1:1. The catalytic activity of the new 50 wt% CoFe 2 O 4 /SiO 2 and 50 wt% CoFe 2 O 4 /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 CoFe 2 O 4 /H-ZSM-5 catalyst exhibited higher activity and stability than CoFe 2 O 4 /SiO 2 catalyst. Maximum methane conversion reached 37.35% and hydrogen formation rate of 76.48 Â 10 À5 mol H 2 g À1 min À1 at time on stream (TOS) of 300 min for CoFe 2 O 4 /H-ZSM-5, while its 5.80% with 15.82 Â 10 À5 mol H 2 g À1 min À1 at TOS of 30 min. The XRD, Raman, and XPS results confirm the presence of CoFe 2 O 4 particles on the CoFe 2 O 4 /H-ZSM-5 catalyst surface, while the CoFe 2 O 4 particles partially shield with SiO 2 in CoFe 2 O 4 /SiO 2 catalyst. SEM images of spent catalysts elucidated the formation of filamentous carbon which indirectly confirm the higher distribution of CoFe 2 O 4 in CoFe 2 O 4 /H-ZSM-5 than that of CoFe 2 O 4 /SiO 2 . The deposited carbon on spent CoFe 2 O 4 /H-ZSM-5 catalyst was evaluated using TGA, which was found to be ca. 50 wt%. Highlights • CoFe 2 O 4 /SiO 2 and CoFe 2 O 4 /H-ZSM-5 catalysts synthesized and characterized by various techniques. • H-ZSM-5 and SiO 2 support material were found strongly affects the physiochemical properties and the methane decomposition activity of CoFe 2 O 4 catalyst. • CoFe 2 O 4 /H-ZSM-5 catalyst performance reached 37.4% and the hydrogen formation rate was 76.5 Â 10 À5 mol H 2 g À1 min À1 .

Hydrogen Production via Methane Decomposition over Alumina Doped with Titanium Oxide‐Supported Iron Catalyst for Various Calcination Temperatures

“…The Fe/Al 2 O 3 catalysts showed two peaks appearing at approximately 350–470 °C (maximum at 400 °C) and 650–750 °C (maximum at 700 °C); the first peak is attributed to the reduction of Fe 2 O 3 to Fe 3 O 4 . In contrast, the second peak represents the transformation of Fe 3 O 4 to Fe [33] . Figure 3 also depicts the impact of TiO 2 on the reducibility and the degree of metal support interaction of the freshly calcined Al 2 O 3 ‐supported Fe catalysts.…”

“…In contrast, the second peak represents the transformation of Fe 3 O 4 to Fe. [33] Figure 3 also depicts the impact of TiO 2 on the reducibility and the degree of metal support interaction of the freshly calcined Al 2 O 3 ‐supported Fe catalysts. The H 2 ‐TPR profiles of Fe/(TiO 2 ‐ Al 2 O 3 ) catalysts calcined at (300, 500, and 800 °C) showed only one distinct reduction peak ranging approximately from 370 to 500 °C, which was assigned to the reduction of Fe 2 O 3 →Fe 3 O 4 .…”

“…In contrast, the second peak represents the transformation of Fe 3 O 4 to Fe. [33] Figure 3 also depicts the impact of TiO 2 on the reducibility and the degree of support. [25] Table 3 presents the degree of reduction (DR) for each catalyst to analyze the observation further.…”

“…To enhance the activity and stability of the Fe‐based catalyst, various promoters, supports, synthesis processes, reactor types, and operating conditions have been investigated to promote a longer catalyst lifetime; these investigations aim at enhancing the surface area of the catalyst, the active metal dispersion on the support, and the metal‘s electronic states while decreasing catalyst sintering. [ 30 , 31 , 32 ] Single oxide materials, such as CeO 2 , [8] SiO 2 , [33] Al 2 O 3 , [34] MgO, [35] and ZrO 2 , [25] are widely utilized as supports for Fe‐based catalysts in the CDM process. For example, Al 2 O 3 has been extensively investigated as support for Fe‐based catalysts because of forming a strong metal–support interaction, which can enhance the reactivity by facilitating the CH 4 dissociation over the metallic Fe active site.…”

Scalable Synthesis of Oxygen Vacancy-Rich Unsupported Iron Oxide for Efficient Thermocatalytic Conversion of Methane to Hydrogen and Carbon Nanomaterials

“…The available evidence indicates that electricity can be efficiently obtained from hydrogen-based sources without any environmental pollution [1][2][3][4]. However, at present, hydrogen is typically attained through methane steam reforming (MSR) and partial natural gas oxidation, resulting in considerable CO 2 emissions [5][6][7]. Thus, greener methane decomposition strategies are urgently required, as methane is superior to all other hydrocarbons in terms of the hydrogen/carbon ratio.…”