Aqueous selective hydroxyl targeting in 2-hydroxyadipic acid for high-selectivity biobased adipic acid

Green synthesis of biobased adipic acid (AA) from hydroxyacid feedstocks is challenging due to competing reactivity of hydroxyl and carboxyl groups. Here, we report an aqueous strategy that enables selective removal of the hydroxyl group in 2-hydroxyadipic acid (2-HAA) using a MoO x -Pd/TiO 2 catalyst with in situ -generated Mo–O–H sites. The catalyst achieves 97.3% selectivity to AA. Kinetic analyses, CO and H 2 pulse titration experiments, in situ X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations show that Mo–O–H sites preferentially interact with the hydroxyl group and promote C–O bond cleavage while suppressing side reactions. This study provides mechanistic guidance for rational catalyst design in upgrading biomass-derived hydroxyacids to value-added diacids.