Abstract
The mechanism and the rate-determining step of the carbon deposition reaction on iron in CH4- H2 mixtures at 1273K have been studied. X-ray diffraction and chemical analysis show that filmy carbon has a well developed crystalline character with crystallite height and interlayer spacing, and that iron is included in it. The growth rate of filmy carbon is controlled by the outward diffusion of iron in the film, while the deposition rate of filamentous carbon is determined by the following overall reaction at the gas-iron interface;
CH4(g)→C(s)+2H2(g).
