Highly Efficient Assembly-Line Production of Long-Chain Hydrocarbons via Fischer–Tropsch Synthesis over Ru/TiO2 Catalysts

The assembly-line strategy serves as an effective way for optimizing tandem steps in the fields of enzyme catalysis and homogeneous catalysis. Herein, we rationally construct efficient Ru/TiO₂ catalysts for an important industrial heterogeneous reaction of Fischer-Tropsch synthesis (FTS), involving CO dissociation, hydrogenation, and C-C coupling complex processes. These catalysts feature an "assembly-line" structure composed of oxygen vacancies (O_v), interfacial Ru (Ru_I^δ+ at Ru_I^δ+-O_v-Ti³⁺), and exposed Ru (Ru_E⁰) sites. Both experimental and theoretical results demonstrate that Ru_I^δ+ sites with the assistance of O_v primarily contribute to CO dissociation and hydrogenation to C1 monomers (workshop 1), while Ru_E⁰ sites predominantly drive the above intermediates to C-C coupling for carbon chain growth (workshop 2). We interestingly discover that besides the performance of the two workshops themselves, their efficient coordination is key to improve the activity and long-chain hydrocarbon selectivity in FTS. Optimizing this trisite catalytic system via tuning the prereduction time of the TiO₂ support robustly achieves an ultrahigh FTS activity (180.8 mol_CO mol_Ru^-1 h^-1) while maintaining an impressive C₅₊ selectivity (90.1%), outperforming the vast majority of state-of-the-art Ru-based FTS catalysts. This work not only clearly clarifies the synergistic mechanisms of multiple active sites but also offers valuable guidance for the application of the assembly-line strategy in complex heterogeneous catalysis reactions.