Mathematical modeling of continuous production of carbon nanofibers from methane in a reactor with a moving bed of a nickel-containing catalyst

The continuous production of carbon nanofibers from methane on a Ni/Al2O3 catalyst (90 wt % Ni) in a plug-flow reactor with countercurrent or cocurrent flows of the phases is considered. The methane conversion, specific carbon content, and relative catalyst activity in the reactor are calculated as functions of the longitudinal coordinate, temperature, and specific gas and catalyst flow rates. It is shown that, at a fixed specific methane flow rate, there is an optimal specific catalyst flow rate at which the specific yield of carbon nanofibers is maximal, with this yield in the cocurrent reactor being higher than that the countercurrent reactor. At certain parameter values, the reactor may contain a region with a virtually deactivated catalyst, which is indicative of inefficiency of use of the reactor space.