(721a) Hydrogen and Carbon Nanomaterials Production By Catalytic Decomposition of Methane over Fe and Co Based Catalysts Supported on CeO2-ZrO2

Catalytic Decomposition of Methane (CDM) to produce high purity hydrogen has drawn interest of many researchers in recent decades. Ni is the most commonly used catalyst while the best proven supports are SiO₂ and Al₂O₃. Recently, studies on CDM have been extended to investigate the role of different support materials like CeO₂, La₂O₃, and TiO₂. In this work, catalytic decomposition of methane was performed over Fe and Co based catalysts supported on a mixed metal oxide (CeO₂-ZrO₂) at 700 ^oC to produce CO_x-free hydrogen and carbon nanostructures (CNS). Monometallic catalysts were prepared by impregnation and bimetallic catalysts were prepared by co-impregnation technique. For 15% Fe/CeO₂-ZrO₂ the initial H₂ yield was ~85% and it dropped to ~30% after 120 min of reaction. Varying Fe concentration in Fe/CeO₂-ZrO₂ catalysts doesn’t significantly affect the catalytic activity and hydrogen yield. In case of 15% Co/CeO₂-ZrO₂, though the H­₂ yield dropped from 95% to 55% in the first 70 min reaction, it then increased to stabilized around 95% after 200 min of reaction. Further, Fe-Co/CeO₂-ZrO₂ with different Fe and Co loadings to enhance the performance of Fe were also investigated. For 15% Fe-10% Co/ CeO₂-ZrO2, the H₂ yield was ~95% after 200 min of reaction. Fe-Co bimetallic catalyst loaded on CeO₂-ZrO₂ exhibited better H₂ yield when compared to other supports reported in literature (30% Fe-15%Co/Al­₂O₃ exhibited 73% H₂ yield after 180 min of reaction). All the fresh and spent catalysts were subjected to BET, SEM, TEM and XRD. Degree of reducibility of fresh catalysts and amount of carbon (including coke) formed on the spent catalysts were studied by TPR and TPO studies respectively. XRD confirmed the presence of both Fe₃C and metallic Fe phases in the spent Fe/CeO₂-ZrO₂ catalyst while elemental Co and CoFe alloy were formed in Co/CeO₂-ZrO₂ and Fe-Co/CeO₂-ZrO₂ spent catalysts, respectively. The SEM and TEM analysis revealed the presence of carbon nanostructures in the spent catalyst and the properties of CNS formed on different catalysts were discussed in detail.