Mathematical modeling of the homogeneous-heterogeneous non-oxidative CH4 conversion: the role of gas-phase H or CH3

Dynamics of the non-oxidative conversion of methane in a moving mixture of the catalyst nanoparticles and the reacting gas is under study using the methods of mathematical modeling. Considered compact mechanism of the reaction takes into account activation of methane both on the surface of the catalyst nanoparticles (NPs) and in the gas phase, with the production of C2Hn, n = 2, 4, 6, C6H6 and H2. At this, the desorption of H or CH3 increases the rates of the reactions in the gas phase. Under the parametric analysis of the kinetic model, we defined some values of the temperature, the energy of catalytic activation of methane and the concentration of the catalyst NPs at which both the methane conversion and the C2H6 and C2H4 selectivity increase. Within the non-isothermal model of the flow fluidized-like bed wall-less reactor we studied the influence of the mass and heat transfer of the conversion of methane and mole fractions of the products of the reaction. In results of the studies, we describe the case when due to the activation of methane the catalyst NPs are cooling, which lead to cooling of the gas via the convective heat transfer. We also simulate the case of the two-temperature regime (the catalyst NPs are colder than the gas phase), which allows maintaining a limited set of products of the reaction, namely, hydrogen, ethane and ethylene.