Dopamine sacrificial coating strategy driving formation of highly active surface-exposed Ru sites on Ru/TiO2 catalysts in Fischer–Tropsch synthesis

Abstract

Generally, strong metal–support interactions of reducible metal oxides supports will cause encapsulation of suboxides on metal catalysts. It inevitably brings the formation of metal–support interfacial sites, and decreases surface-exposed metal sites. Herein, we synthesize Ru/TiO2 catalysts through a dopamine sacrificial coating strategy, which significantly increases the number of surface-exposed Ru sites with the high dispersion. The as-synthesized Ru/TiO2-500-H catalyst exhibits the high Fischer–Tropsch synthesis performance and catalytic stability. We discover that the TOF of surface-exposed Ru sites is 5.3-fold that of interfacial ones in our catalyst system. Moreover, surface-exposed Ru sites could thermal-stably adsorb CO, stimulate the chain growth and promote the C5+ selectivity by strengthening the bond between CHx intermediates and metal sites, as evidenced by in situ characterizations operated under real operating conditions. Our findings provide comprehensive understandings of rationally designing highly efficient metal catalysts, which can be potentially applied in other related catalysis systems.