Thermal decomposition and cobalt species transformation of carbon nanotubes supported cobalt catalys

The effect of calcination condition on the cobalt species and Fischer-Tropsch synthesis (FTS) was studied.It was found that higher calcination temperature resulted in decreased FTS activities because CNTs were consumed by oxidation in air at temperature higher than 230 ℃.Cobalt species went through transformation from Co3O4 to metallic Co in Ar by autoreduction at temperature over 500 ℃.The autoreduction route might be Co3O4→CoO→Co or Co3O4→Co2C→Co.Reduction at temperature higher than 500 ℃ also resulted in decreased FTS activities due to the methanation of CNTs in hydrogen.