Modulating Cu+/Cu0 Sites on Cu Nanoparticles via Halogen Modification for Controllable Hydrogenation of Furfuryl Alcohol to Cyclopentanone and Cyclopentanol

Cascade catalytic upgrading of biomass-derived furanic compounds to high-value cyclopentanone (CPO) and cyclopentanol (CPL) over metal–acid bifunctional catalysts has attracted considerable attention in sustainable chemistry. However, conventional bifunctional catalysts exhibit insufficient synergistic effects, primarily due to the lack of flexibility in tuning the ratio of acidic to hydrogenative active sites. Herein, we demonstrate that halogen (Br and Cl) modification of supported Cu catalysts significantly enhances both activity and selectivity in the aqueous-phase hydrogenative rearrangement of furfuryl alcohol (FOL), achieving a CPO yield of 94.4% and a CPL yield of 94.6%, respectively. Extensive characterizations reveal that the electronegative Br and Cl adatoms effectively modulate the electronic state of Cu nanoparticles, facilitating the formation of Lewis acidic Cu + sites on the catalyst surface. Mechanistic investigations disclose that Cu + sites mediate the rearrangement of FOL to 4-hydroxy-2-cyclopentenone (4-HCP), while adjacent Cu 0 sites catalyze the hydrogenation of 4-HCP to CPO, followed by its subsequent hydrogenation to CPL. Different binding strengths between Cu and halogens (I > Br > Cl) allow the regulation of the Cu + /Cu 0 ratio on the Cu surface, which in turn provides an effective way to control the reaction pathway. The developed halogen modification strategy not only offers great potential for the upgrading of biomass-derived furanics to cyclopentane derivatives but also presents a versatile strategy for regulating the surface Lewis acidity of metal catalysts, which is crucial for metal–acid bifunctional catalysis.