Construction of Synergistic Co/CoO Interface to Enhance Hydrogenation Activity of Ethyl Lactate to 1,2-Propanediol

The development of effective and stable non-precious catalysts for hydrogenation of ester to diols remains a challenge. Herein, the catalytic hydrogenation of ethyl lactate (EL) to 1,2-propanediol (1,2-PDO) with supported Co catalysts derived from layered double hydroxides (LDHs) is investigated. Catalytic tests reveal that LDH-derived Co catalysts exhibit the best catalytic performance with 98 % of EL conversion and >99 % of 1,2-PDO selectivity at mild conditions, compared with other Co catalysts (supported on Al₂O₃, and TiO₂) and LDH-derived Cu catalysts. Due to the strong interaction among Co and Al matrix, the main composition is metallic Co⁰ and CoO after reduction at 600 °C. Besides, the catalyst shows good recyclability in the liquid phase hydrogenation. The superior catalytic performance can be attributed to the synergistic effect between Co⁰ and CoO, in which H₂ molecule is activated on Co⁰ and EL is strongly adsorbed on CoO via hydroxyl groups.