Study of Co/γ-Al2O3 and Fe/γ-Al2O3 materials for catalytic methane pyrolysis to CO2-free hydrogen
Eleni Pachatouridou, Elpida Zeza, Angelos A. Lappas, Eleni F. Iliopoulou
Abstract
Cobalt and iron (5 wt%) supported on γ-alumina catalysts are evaluated for CH 4 pyrolysis reaction. The effect of synthesis method (Wet Impregnation, WI vs. Spray Impregnation, SI) and of catalyst promotion with 0.5 wt% Pd are investigated. All catalysts are pre-reduced and fully characterized. Undoped Co/γ-Al 2 O 3 catalysts present poorer performance (∼6% CH 4 conversion at 700 °C) than Fe/γ-Al 2 O 3 (∼20% conversion at 850 °C) after 30min of reaction. In all cases SI method enhances catalyst activity. Although Pd addition affects inconsiderably the Fe catalysts, presenting similar activity to the unpromoted catalyst, it significantly enhances Co catalysts performance increasing and stabilizing CH 4 conversion at 70% for 30 min. Spray Impregnated Pd–Co catalyst is tested for 8 h of reaction and a gradually diminishing, but still encouraging methane conversion to 29% is observed. Besides the importance of CH 4 pyrolysis as a suggested method for clean H 2 production, the co-produced carbon structures are also worth studying. Thus, the results obtained from XRD , SEM and TEM indicated formation of carbon nanofibers (CNFs) of various dimensions.