Galvanic deposition of silver on 80-μm-Cu-fiber for gas-phase oxidation of alcohols

Microstructured Ag-based catalysts were developed by galvanically depositing Ag onto 80-μm-Cu-fibers for the gas-phase oxidation of alcohols. By taking advantages including large voidage, open porous structure and high heat/mass transfer, as-made catalysts provided a nice combination of high activity/selectivity and enhanced heat transfer. The best catalyst was Ag-10/80-Cu-fiber-400 (Ag-loading: 10 wt%; Cu-fiber pretreated at 400 °C in air), being effective for oxidizing acyclic, benzylic and polynary alcohols. For benzyl alcohol, conversion of 94% was achieved with 99% selectivity to benzaldehyde at 300 °C using a high WHSV of 20 h^-1. Computational fluid dynamics (CFD) calculation and experimental result illustrated significant enhancement of the heat transfer. The temperature difference from reactor wall to central line was about 10-20 °C for the Ag-10/80-Cu-fiber-400, much lower than that of 100-110 °C for the Ag-10-Cu-2/Al₂O₃ at equivalent conversion and selectivity. Synergistic interaction between Cu₂O and Ag was discussed, being assignable to the activity improvement.