Efficient and selective valorization of biomass-derived furfural to cyclopentanone via synergistic acidic PdAg/carbon dots catalysis

The conversion of furfural (FF) to cyclopentanone (CPO) via selective hydrogenation-rearrangement represents a crucial route for sustainable, high-value valorization of renewable biomass feedstocks. In this study, carbon dots (CDs) were utilized as both a reducing and a dispersing agent for the one-pot green photoreduction synthesis of PdAg bimetallic catalysts supported on CDs (Pd x Ag y /CDs) in aqueous phase. Among the catalysts with varying Pd-to-Ag molar ratios, the Pd 0.5 Ag 1 /CDs catalyst demonstrated exceptional performance, achieving 100 % FF conversion and 93.3 % CPO selectivity within 4 h at 200 °C. The superior activity is attributed to a synergistic effect between the acid sites on the CDs and the PdAg alloy, which facilitates the rearrangement of the intermediate furfuryl alcohol (FA). Mechanistic studies, including calculations of the free energy barriers for elementary steps from FA to 4-hydroxy-2-cyclopentenone, revealed a ring-opening pathway for the furan methyl carbocation, which dramatically reduces the reaction energy barrier to 47.1 kJ/mol from 195.8 kJ/mol of the Piancatelli pathway. This work not only presents an efficient and green catalyst for FF upgrading but also highlights the promising application of CDs in advanced catalytic systems for circular economy-driven chemical production.