Iron and copper nanoparticles inside and outside carbon nanotubes: Nanoconfinement, migration, interaction and catalytic performance in Fischer-Tropsch synthesis

•Mobility of metal species in bimetallic carbon nanotube supported catalysts.•No migration of metal species in the monometallic catalysts.•Higher turnover frequency over iron sites in proximity with copper.•Mobility enhances interaction of iron with the promoter.•Fragility of carbon nanotubes on impregnation and precursor decomposition.