Directional synthesis of high-density aviation fuel through CO2 hydrogenation coupling with naphthalene alkylation over ZnZrOx/Hβ catalyst

Hydrogenation of CO₂ and green H₂ into sustainable high-density aviation fuels is a crucial route to satisfy the high-performance fuel demands of advanced aircrafts and facilitate carbon neutrality in the aviation industry, whereas existing technologies mainly produce low-energy-density components. Herein, coupling CO₂ hydrogenation with polyaromatic alkylation is proposed to synthesize alkylated polycyclic hydrocarbons with high energy density and superior low-temperature property. The effect of electronic interactions in the ZnZrO_x/Hβ catalysts prepared utilizing oxalate-mediated precipitation strategy on the coupling reaction of CO₂ hydrogenation and naphthalene alkylation was proverbially investigated. Appropriate Zn incorporation is beneficial to boost the electronic action within ZnZrO_x solid solutions and generate abundant electron-rich Zn species and oxygen defects, thereby promoting the production of more methoxy intermediate derived from CO₂ hydrogenation for the alkylation with naphthalene. The ZnZrO_x/Hβ catalyst with molar ratio of 1:8 showed the optimal space time yield of 5.9 μmol·g-1 oxide·s⁻¹ and selectivity of 86.4 % for alkylnaphthalene at 360 °C under 4 MPa. Moreover, it also presented exceptional long-term catalytic stability over a 100 h on stream, exhibiting outstanding industrial application prospects. In situ DRIFTS and DFT simulations showed that CO₂ preferentially formed *H₃CO by formate route in ZnZrO_x and then diffused to Hβ zeolite for alkylation, establishing a coupled transformation pathway for the preparation of alkylnaphthalene. After blending with JP-10, the high-density aviation fuel with superb density of 0.949 g·mL⁻¹ was obtained, which also illustrated higher oxidation onset temperature of 219.6 °C and shorter ignition delay time of 2276 ms, providing a novel pathway and theoretical foundation for the directional synthesis of sustainable high-density aviation fuels.