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 Co-0 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 Co-0 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.