Nitrogen-doped carbon species: a promising nonmetallic promoter for the Co/SiO2 Fischer–Tropsch synthesis catalyst

A dicyandiamide (DCDA)-additive impregnation method was used to prepare SiO2 supported Co catalyst (i.e. Co/SiO2-CN). The addition of DCDA molecules could produce nitrogen-doped carbon species with predominant pyrrolic nitrogen atoms on the SiO2 support. The nitrogen-doped carbon species formed not only improved the reduction of Co3O4 particles, but also facilitated the electron transfer from the pyrrolic nitrogen atoms to neighboring metallic Co0 particles during reduction on the Co/SiO2-CN catalyst, in contrast to the conventional impregnation derived Co/SiO2-IWI sample. Such an effect ameliorated the electron-deficient state of metallic Co0 particles that existed on the Co/SiO2-IWI catalyst and was favorable to CO dissociation. As a result, the DCDA-additive method derived Co/SiO2 shows a higher turnover frequency value than the conventional Co/SiO2-IWI catalyst in the Fischer–Tropsch synthesis reaction.