Surface Oxygenate Species on TiC Reinforce Cobalt-Catalyzed Fischer-Tropsch Synthesis

Carbide-supported metal catalysts attract extensive research interests owing to the special properties of metal carbide and the interactions between metals and the carbide supports. While surface oxide species are inevitable in carbide materials, their roles in metal-carbide interaction have not been thoroughly studied. Herein, TiC-SiC supported cobalt catalyst was investigated in Fischer-Tropsch synthesis to understand the metal-support interaction (MSI). Compared with the Co/SiC catalyst, the TiC-SiC supported catalyst presents superior intrinsic activity (TOF, 0.24 s(-1)). By using in situ NAP XPS and environmental STEM, the predominant presence of surface TiOx species and the subsequent formation of a Co-TiOx overlayer were observed. The results suggest that the MSI in the Co/TiC-SiC system is modulated by the Co-TiOx interaction, thus improving the catalytic activity. This work reveals the often overlooked but important role of surface oxides on carbides in metal-carbide interactions and paves the way for the future rational design of advanced catalysts.