Efficient dehydrogenation of dodecanol to dodecanal in a continuous fixed bed reactor over supported Cu catalyst

The anaerobic dehydrogenation of dodecanol to dodecanal has been investigated in a continuous fixed bed reactor over a series of Cu-based catalysts with different supports (SiO₂, Al₂O₃, ZnO and MgO). These catalysts have been systematically characterized by XRD, H₂-TPR, NH₃-TPD, CO₂-TPD, XPS and N₂ adsorption/desorption measurements. And the results indicate that the support has significant effect on the physicochemical properties of the catalysts and their catalytic performances, and Cu/SiO₂ exhibited the highest catalytic activity in the dehydrogenation. Synergistic effect between Cu⁺ and Cu⁰ species has been observed, and proper ratio of Cu⁺/Cu⁰ is believed to be able to improve the catalytic performance of Cu-based catalysts. The surface acidity and basicity demonstrate significant effect on the distribution of the products and the selectivity to aldehyde. Under the optimized conditions, an 82.3% conversion of dodecanol with an excellent 98.9% selectivity toward dodecanal could be obtained. Moreover, the catalytic performance of Cu/SiO₂ kept almost steady in 200 h, indicating its good stability and application potential in the dehydrogenation process.