Effect of TiO₂ Surface Engineering on the Performance of Cobalt-Based Catalysts for Fischer–Tropsch Synthesis

A series of surface-modified TiO2 samples (Al-TiO2, Si-TiO2, and C-TiO2) with similar physical properties were synthesized. Comparison of the profound effect of different interfaces of the Co catalyst on the activity and stability in Fischer–Tropsch synthesis was investigated. Al2O3 or SiO2 nanoshell-modified TiO2 enhances the cobalt dispersion (Co/Al-TiO2) or reducibility (Co/Si-TiO2), which results in an increased cobalt-time-yield (CTY) of the catalysts. Hydrothermal carbon (HTC) shell modified TiO2 can simultaneously promote cobalt nanoparticle dispersion and reducibility. Accordingly, compared with the reference Co/TiO2 catalyst, the CTY and C5+ selectivity of Co/C-TiO2 is remarkably improved. Furthermore, the Co/C-TiO2 catalyst shows more stabilized activity under harsh FTS reaction conditions (230 °C, 1.0 MPa, CO conversion over 60%). This stable catalysis is attributed to the interfacial site (Co-TiO2), with the strength of the metal–support interaction resulting from the autoconsumption of the HTC layer during the reduction and reaction processes