Direct conversion of CO2 to aromatics with high yield via a modified Fischer-Tropsch synthesis pathway

Abstract

The direct conversion of CO2 to aromatics not only reduces carbon emissions but also provides an alternative way for value-added chemicals synthesis. Even though the hydrogenation of CO2 to aromatics has been realized via a methanol-mediated pathway or a modified Fischer-Tropsch synthesis route, low yield of aromatics is still the bottleneck of this strategy. Here, we develop a multifunctional catalyst composed of Na modified Fe-based catalyst and hollow acidic zeolite H-ZSM-5 to catalyze the hydrogenation of CO2 to aromatics by single pass. Na modified Fe-based catalyst prepared by pyrolysis of Fe-based metal-organic frameworks (Fe-MOFs) can boost the formation of alkenes intermediates because of its high active sites accessibility and precisely tailored catalytic interfaces. Thereafter, the produced alkenes can be converted to aromatics via the dehydrogenation and cyclization reactions when they diffuse to the acid sites of H-ZSM-5. The hollow H-ZSM-5 with short diffusional channels, appropriate density and strength of acid sites guaranteed the high yield of aromatics (203.8 gCH2 kgcat−1 h−1). Furthermore, the driving force in the tandem process can be attributed to the cooperative interplay between the multifunctional catalysts. The CO2 adsorbed on Fe-based catalyst can be employed as acceptors for H species produced from the dehydrogenation and cyclization reactions, thereby increasing the yield of aromatics by shifting the chemical thermodynamic equilibrium.