A comparison of co-current and counter-current modes for Fischer-Tropsch synthesis in two consecutive reactors of oxidative coupling of methane and Fischer-Tropsch

The results of three cases of two consecutive reactors are studied in two types of co-current and counter-current flow in second reactor where two consecutive reactors are oxidative coupling of methane (OCM) and Fischer-Tropsch (FT) reactors. FT reactor can be fixed bed or membrane fixed bed reactor with a hydrogen perm-selective membrane. Effect of CH4/O2 ratio, contact time, inlet temperature, and amount of N2 in OCM feed on C2 to C5+ hydrocarbons produced in FT reactor were studied. Results show that use of counter-current hydrogen-perm selective membrane FT reactor that sequenced after OCM reactor improves the C5+ yield as a desirable product and reduces the amount of CH4 and CO2 as byproducts of FT reactor in comparison to co-current and conventional reactor. This phenomenon can be explained with more H2 diffusion through the membrane and more CO conversion and more hydrocarbons productions, briefly. As compared to the conventional reactor, in co-current and counter-current reactors, yield of C5+ has increased almost 3% and 4% alternatively when using these systems.