Thermal coupling of methane, experimental investigations on coke deposits Original Research Article

We have studied the formation of coke during the thermal coupling of an equimolecular methanehydrogen mixture at 1230 °C and under a one-atmosphere pressure. Coke samples are recovered in rectangular boats placed along the pyrolysis reactor. The deposits show a non-homogeneousness of coke along the reactor in terms of deposition rate and in terms of structure. We observed at least two kinds of coke that settle at different rates along the pyrolysis reactor: (a) a silver-grey, uniform film and (b) a black powder. Transmission electron microscopy and oxidative pyroanalysis showed that the former is a well crystallized graphite-type coke with a highly refractory character, while the latter corresponds to amorphous powder carbon.