Unraveling synergy at the CuCo oxide interface for direct dehydrogenation of lactic acid to pyruvic acid

The direct dehydrogenation of lactic acid (LA) to pyruvic acid (PyA) presents a sustainable and atom-economical route for biomass valorization, yet it demands high-performance catalysts to achieve satisfactory activity and selectivity. While bimetallic catalysts often show enhanced performance, a deep understanding of the interfacial synergy remains a challenge. Herein, we report a series of CuCo bimetallic oxide catalysts that exhibit remarkable performance in the direct dehydrogenation of LA to PyA, significantly outperforming their monometallic counterparts. A combination of detailed catalyst characterization and kinetic analyses unravels the critical role of the CuCo oxide interface. It is demonstrated that the Co sites at the interface are primarily responsible for the activation and cleavage of the α-C-H and α-O-H bond in lactate, while the adjacent Cu species facilitate the stabilization of the reaction intermediate and the recombination and desorption of hydrogen. This synergistic cooperation at the interface not only promotes the reaction rate but also effectively suppresses undesired side reactions, such as decarbonylation and dehydration, thereby ensuring high selectivity to PyA. The optimized catalyst with a Cu/Co molar ratio of 3:2 demonstrated enhanced performance, delivering 73.4% LA conversion and 78.1% PyA selectivity at 300 °C, which surpasses the results obtained over the CuO 1-x /SiO₂-H400 benchmark under identical conditions. This work provides fundamental insights into the bifunctional mechanism of bimetallic oxides in direct dehydrogenation reactions, offering a strategic guideline for the rational design of efficient and selective catalytic systems for sustainable chemistry.