A Circulating Fluidized Bed CH₄ Reformer: Performance of Supported Ni Catalysts

A methane reformer using a circulating fluidized bed is proposed for the production of hydrogen and synthesis gas (syngas). A catalyst is circulated between two reactors for the catalytic decomposition of methane to hydrogen and carbon and for the gasification of the carbon deposited on the catalyst. Of the metals Cu, Fe, Ni, and W, only Ni showed catalytic activity for the decomposition of methane at 873-1023 K. While studying the structure of the catalyst, it was found that the form of nickel was circulated between oxide and metal through reduction with methane and oxidation with carbon dioxide. X-ray diffraction (XRD) and scanning electron microscopy (SEM) suggested that filamentous carbon having a graphitic structure was gasified with carbon dioxide and that carbon having a mosslike morphology was hardly gasified and caused deactivation of the catalyst. The reactivity of the carbon which was able to be gasified was not altered with cycles of methane decomposition and carbon dioxide gasification.