Selective production of jet-range hydrocarbons via CO₂ hydrogenation over Fe-based and Pt/zeolite tandem catalysts

Direct hydrogenation of CO₂ into long-chain hydrocarbons is a promising method for producing sustainable aviation fuels (SAFs). However, achieving high selectivity toward C₈–C₁₆ n-paraffins and isoparaffins, which are crucial components of jet fuel, remains a major challenge owing to the complex reaction pathways and broad product distributions of Fe-based Fischer-Tropsch synthesis (FTS). In this study, a tandem catalytic system comprising a Fe-based FTS catalyst (Na-FeAl, NFA) and a Pt-loaded zeolite (Pt/HZSM-5, Pt/HZSM-22) was developed to enhance the selectivity for paraffins within the jet fuel range. The composition of the NFA catalyst was optimized to facilitate CO₂ activation and C-C coupling to produce olefin-rich intermediates, while the Pt/zeolite catalyst promoted the hydroisomerization and hydrogenation of the intermediate olefins to n- and isoparaffins. A systematic investigation of the zeolite framework type, Si/Al ratio, Pt loading, and spatial configuration revealed substantial effects on chain growth and product distribution. Under the optimized reaction conditions (320 °C, 3.0 MPa, H₂/CO₂ = 3:1), the tandem catalyst in dual bed configuration (NFA||Pt/HZSM-22) achieved a high CO₂ conversion of 40.7 %, and it significantly enhanced the paraffin selectivity within the C₈–C₁₆ range, reaching up to 64.7 %. These findings provide key insights into the design of integrated catalytic systems for CO₂ valorization and contribute to the advancement of carbon-neutral aviation fuel technologies.