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

Abstract

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.