Hydrophobic fluorinated superacid resins for water‐tolerant C‐C coupling to high‐density bio‐jet fuels

Abstract Upgrading biomass to high‐performance fuel offers an effective solution to energy crisis and carbon neutrality goals, however, most value‐added reaction suffers from byproduct water‐induced deactivation of acid catalysts and consequent side reactions. Herein, novel hydrophobic oleophilic mesoporous fluorinated sulfonic acid resins with exceptional thermostability, superacidity, and tunable acid density were facilely synthesized via free‐radical copolymerization and subsequent ion exchange. The optimal FSA‐2 achieves a record bicyclic product yield of 76.7% in self‐aldol condensation of cyclohexanone and a high tricyclic yield of 74.5% in alkylation of 2‐methylfuran with cyclohexanone, significantly outperforming commercial Amberlyst‐15, Nafion‐212, and zeolite catalysts. Its superior activity arises from superacid sites, suitable acid density, and excellent hydrophobicity‐oleophilicity, enabling FSA‐2 to be recycled steadily for four consecutive runs. Subsequent hydrodeoxygenation affords three high‐energy‐density bio‐jet fuels with densities of 0.825, 0.881, and 0.887 g/mL, respectively. This work provides a scalable solid acid platform for bio‐jet fuel production from lignocellulose‐derived compounds.