Ni-SiO₂ and Ni-Fe-SiO₂ catalysts for methane decomposition to prepare hydrogen and carbon filaments

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• 作者：Wenhua Wang ; ^{Wangwenhua19860610@126.com} ; Heyi Wang ; Yong Yang ; Shubin Jiang
• 关键词：Methane decomposition ; Ni&ndash ; Fe&ndash ; SiO2 ; Carbon filament ; Hydrogen
• 刊名：International Journal of Hydrogen Energy
• 出版年：2012
• 期刊代码：42_03603199
• 类别：ch
• 出版时间：June, 2012
• 卷：37
• 期：11
• 页码：9058-9066
• 文件大小：1363 K

摘要

Active and stable Ni-Fe-SiO₂ catalysts prepared by sol-gel method were employed for direct decomposition of undiluted methane to produce hydrogen and carbon filaments at 823 K and 923 K. The results indicated that the lifetime of Ni-Fe-SiO₂ catalysts was much longer than Ni-SiO₂ catalyst at a higher reaction temperature such as 923 K, however, a reverse trend was shown when methane decomposition took place at a lower reaction temperature such as 823 K. XRD studies suggested that iron atoms had entered into the Ni lattice and Ni-Fe alloy was formed in Ni-Fe-SiO₂ catalysts. The structure of the carbon filaments generated over Ni-SiO₂ and Ni-Fe-SiO₂ was quite different. TEM studies showed that 鈥渕ulti-walled鈥?carbon filaments were formed over 75%Ni-25%SiO₂ catalyst, while 鈥渂amboo-shaped鈥?carbon filaments generated over 35%Ni-40%Fe-25%SiO₂ catalysts at 923 K. Raman spectra of the generated carbons demonstrated that the graphitic order of the 鈥渕ulti-walled鈥?carbon filaments was lower than that of the 鈥渂amboo-shaped鈥?carbon filaments.