Co ⁰ /O _v -Co Synergy in Co–Al Metal–Metal Oxide Catalysts by Atomic Ratio Control for the Efficient Fatty Acid Hydrogenation to Fatty Alcohol

Selective hydrogenation of carboxylic acids to alcohols remains a challenge due to the requirement of synergistic multiple active sites for H2 activation, reactant adsorption, and selective C–O bond scission. Here, we construct a series of Co–Al metal–metal oxide (MMO) catalysts via the hydrogen-induced reduction of layered double hydroxide (LDH) precursors with tunable Co/Al ratios. The optimal Co4Al1-MMO catalyst exhibits highly dispersed Co0 nanoparticles alongside abundant oxygen vacancies (Ov-Co). The Co0/Ov-Co dual sites synergistically promote H2 dissociation and carbonyl oxygen C=O bond activation, while moderate lattice oxygen stabilizes the metastable structure. Under mild conditions (180 °C, 2 MPa of H2, 3 h), the catalyst achieves 100% conversion of octanoic acid with 99% alcohol selectivity, outperforming state-of-the-art noble-metal systems. This work provides a general strategy for engineering cooperative metallic/defective sites in nonprecious MMO catalysts for selective hydrogenation reactions.