The decomposition of methane over Ni/Ca/carbon catalyst systems, to form hydrogen and carbon was examined at modest temperature range of 623-873K. The catalytic activity of these systems proceeded after pretreatment by air at 573K for 4h, and by H2 at 673K for 3h. In these systems, nickel was the major active component and the calcium acted as a promoter. The effect of carbon supports on the initial catalytic activity was found to be not so great, but a pronounced effect of these carbons on the

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... rate of reaction with time was observed and pyrolytic carbons prepared from organic monomers, such as cyclododecane, seemed favorable. Carbonaceous species formed by decomposition of methane was presumed to be mainly of those in a filament-like graphite phase.