Low-temperature oxidation of corn straw hydrolysate to sugar acids catalyzed by amine-functionalized biochar supported palladium: Kinetics, thermodynamics, and DFT insights

The development of efficient catalytic systems for the low-temperature oxidation of biomass-derived sugars to value-added acids remains a key challenge in sustainable biorefining. In this study, a palladium catalyst supported on amine-functionalized biochar (Pd/BC-NH 2 ) derived from corn straw for the oxidation of corn straw hydrolysate. The catalyst achieved an exceptional total sugar acid yield of 88.2% under mild conditions at 323 K with NaHCO 3 weak base. Comprehensive characterization confirmed successful amine functionalization and Pd immobilization. Kinetic and thermodynamic analyses determined an activation energy of 41.88 kJ·mol −1 and revealed endothermic, non-spontaneous reaction characteristics. DFT calculations elucidated the mechanism, identifying hydroxide ion-assisted aldehyde C − H cleavage as the rate-determining step with an energy barrier of 56.92 kJ·mol −1 . The superior performance is attributed to a synergistic mechanism where NH 2 groups enrich surface OH − concentration and electronically modulate Pd sites. The catalyst maintained excellent stability over 10 cycles. This study provides a sustainable “waste-to-wealth” strategy for biomass valorization using a straw-derived catalytic system, supported by comprehensive mechanistic insights.