Synthesis of Flower-like Alumina Microspheres Assisted via a Surfactant for Catalytic Transfer Hydrogenation of Furfural

Furfural is a prominent biomass-derived platform compound. Catalytic transfer hydrogenation enables the hydrogenation of furfural without external hydrogen. In this regard, alumina microspheres combining unsaturated aluminum sites, surface acid–base sites, and hierarchical pore structure represent potential catalysts for this process. Herein, hierarchically structured flower-like alumina microspheres (FAMS) with precisely modulated surface properties were synthesized via a surfactant-directed strategy. A comparative study of microspheres synthesized with structurally different surfactants revealed that flower-like alumina microspheres prepared using the double-hydrophobic tail surfactant AOT exhibited expanded mesopores, an enriched penta-coordinated aluminum (Al V ), and superior acidic site density. Meanwhile, the linear cationic CTAB can generate more basic sites on FAMS. In the CTH of furfural to furfuryl alcohol, FAMS-AOT achieved a maximum overall reaction rate and complete furfural conversion to furfuryl alcohol within 2 h at 150 ° C. Comparisons with other surfactant-derived FAMS indicate that a higher absolute Al V relative content drives the macroscopic reaction rate, while the surface basic sites prompted acid–base synergy to improve TOF. This work provides a facile and promising pathway for the surface modulation of alumina microspheres toward the conversion of furfural into furfuryl alcohol.