Pd–Cu/SiO2 catalyzed efficient hydrogen transfer of cyclohexanol and furfural platforms into cyclohexanone and furfuryl alcohol

High–performance and cost–effective designing of bimetallic catalysts is crucial for the efficient biomass–derived cyclic platforms conversion into fuel additives. To improve the hydrogen transfer efficiency between cyclohexanol and furfural, a Pd–Cu/SiO2 composite with self–synthesized mesoporous SiO2 support was developed and characterized. The state of Pd-Cu metal and catalyst surface were investigated through XRD, TEM, XPS, IR, H2–TPR and NH3–TPD. The transfer hydrogenation of furfural into furfuryl alcohol through cyclohexanol dehydrogenation in the liquid phase was investigated and completed in hydrogen acceptor to donor molar ratios of 1:6–1:1.5, with significantly improved furfural hydrogenation capacity, achieving 84.6 % of furfuryl alcohol species molar yield with 97.7 % selectivity at 195 °C, 10 h, in 1:3 M ratio. The reaction was promoted in a molar ratio of 1:1 unprecedentedly without hydrogen wasted, and the reactant and product platforms were further investigated for the condensation synthesis of C11 fuel additives. Reaction mechanism was investigated using 1,4–cyclohexanediol as model reactant at 240 and 280 °C, confirming the high selectivity of products originated from the non–planar adsorption state of reactant on the metal catalyst. This simple and active Pd–Cu bimetallic catalytic system may offer a cutting–edge liquid biofuel production pathway with potential industrial application due to its excellent stability and reproducibility.