LAWS GOVERNING THE HIGH-TEMPERATURE PYROLYSIS OF METHANE ON A MOLYBDENUM CARBIDE SURFACE

We have investigated the kinetic laws governing the high-temperature interaction of methane (2-100 mm Hg, 1400-2200-degrees-C) with molybdenum wire. Kientic laws have been derived for the pyrolysis of methane on a molybdenum surface, and a P-T diagram has been constructed showing the possible kinetic regimes for pyrolysis and carbidization. It was found that at low pressures pyrolysis occurs in one or two stages and is described by a linear law. The temperature dependence of the rate of pyrolysis is given by the following expressions: v1 = v01 (P)exp[-(50,000 +/- 2000)/RT] for the phase Mo2C, and v2 = v02 (P)exp[-(66,000 +/- 2000)/RT] for the phase MoC. On raising the pressure the linear dependence changes into a parabolic one which at high pressures applies right from the beginning of the process.