Direct Conversion of CO₂to Aromatics over K-Zn-Fe/ZSM-5 Catalysts via a Fischer-Tropsch Synthesis Pathway

A series of Fe-Zn catalysts promoted by potassium were successfully prepared by a coprecipitation and incipient wetness impregnation method. The obtained K-Fe/Zn catalysts exhibited excellent performance for CO2 hydrogenation toward C2-C4 olefin formation with high selectivity. A series of efficient bifunctional K-Zn-Fe/ZSM-5 catalysts for CO2 hydrogenation were constructed by combining the K-Fe/Zn catalysts with H-ZSM-5 with different SiO2/Al2O3 ratios, which exhibited a superior aromatics selectivity especially when utilizing a zeolite with NaOH solution pretreatment. Meanwhile, the relationships between catalytic performance and the microenvironment of zeolite were systematically studied. Furthermore, the correlation between aromatic selectivity and H-ZSM-5 weight was also investigated in detail. Combined with experimental data and theoretical analysis, the alkenes produced from K-Fe/Zn could be effectively converted into aromatics via in situ dehydrogenation and cyclization on the acidic sites of H-ZSM-5. The bifunctional catalyst presented the highest aromatics selectivity of 45.2%, with a CO2 conversion of 42.6%.