External Mass Transfer Performance Studies in a Micropacked Bed Reactor with Pd/PDA/Nickel Foam

The coating materials of monolithic foam catalysts have a remarkable influence on the mass transfer and reaction process of packed bed reactors. However, the external mass transfer performance of micropacked bed reactors (μPBRs) based on the organic polymer-coated foam catalyst has not been investigated. This study explores the α-methylstyrene hydrogenation reaction and external mass transfer performance of μPBRs with a polydopamine (PDA)-coated foam catalyst. Pd/PDA/nickel foam has excellent α-methylstyrene hydrogenation activity and stability compared to Pd/Al₂O₃/nickel foam in μPBRs. The effect of pressure, gas and liquid superficial velocities, and pore size of foam packing on external mass transfer coefficient ((ka)_OV) was investigated. The (ka)_OV of the PDA-coated foam packing can reach 0.31-1.03 s^-1, which shows a notable improvement over the Al₂O₃ coating. Furthermore, an empirical correlation equation for (ka)_OV in μPBRs with PDA-coated foam packing is developed to provide a foundation for further design optimization and industrial applications.