Fabrication of bimetallic RuCu/HAP catalysts for the selective synthesis of C₁₁ biofuel precursors from biomass-based 5-methylfurfural

The synthesis of bis(5-methylfuran)methane (BMFM) from biomass-based 5-methylfurfural (5-MF), a vital fuel precursor, is crucial for biomass refining. However, selective BMFM production from 5-MF needs to suppress side reactions such as hydrogenolysis and decarbonylation. Therefore, direct hydrogenation of 5-MF into BMFM is very challenging in sustainable biomass valorization. In this study, we developed a bimetallic RuCu/hydroxyapatite (HAP) catalyst for selective synthesis of BMFM from 5-MF. The RuCu/HAP catalyst delivered a BMFM yield of 75.6% under mild reaction conditions (<i>V</i> _water : <i>V</i> _cyclohexane = 1 : 1, 4 MPa H₂, 100 °C, 4 h), significantly surpassing its monometallic counterparts (Ru/HAP: 28.7%; Cu/HAP: 0%). Furthermore, a 79% yield of C₁₁ straight-chain alkanes was obtained from BMFM through the hydrodeoxygenation (HDO) process. The systematic characterization revealed that Ru mediates hydrogenation steps <i>via</i> C[double bond, length as m-dash]O activation, while Cu orchestrates acid sites essential for self-condensation of 5-MFA. The synergistic interplay between metallic Ru and acidic Cu sites thereby enables simultaneous optimization of conversion efficiency and BMFM selectivity. These findings provide a practical and efficient route for converting lignocellulosic derivatives into renewable biofuels, particularly for sustainable aviation fuel applications.