Fine-tuning cobalt for cleaner chemical transformations

Scientists at Yokohama National University have discovered a way to enhance the performance of cobalt catalysts in hydrogenation reactions, potentially offering a more sustainable alternative to precious metals in chemical manufacturing. Cobalt, an earth-abundant metal, can be tuned to selectively hydrogenate nitrogen-containing compounds by carefully adjusting the balance between metallic cobalt and cobalt oxide.

The researchers found that a specific ratio of the two forms of cobalt—metallic Co(0) and cobalt oxide, CoOx—produced the best catalytic performance. Electrochemical experiments revealed that this intermediate Co(0)/CoOx ratio created a favorable environment for pyridine adsorption and hydrogenation, yielding over 99% conversion of pyridine to piperidine under ambient conditions.

The catalyst also selectively hydrogenated a range of nitrogen-containing compounds while minimizing unwanted side reactions. To ensure long-term stability, the team introduced intermittent electrolysis, which helped maintain the optimal Co(0)/CoOx balance during extended operation. The findings demonstrate that actively controlling a catalyst's chemical state during operation is crucial for effective catalysis, potentially paving the way for scalable electrochemical processes that rely on abundant materials rather than scarce precious metals.