Performance of ceramic foams as gas–liquid contactors for phenol wet oxidation in the trickle regime

• Foam beds can be used for phase contact in trickle-bed reactors.
• Phenol wet oxidation demonstrated in a foam bed reactor.
• Liquid superficial velocity should be high enough to favour mass transfer.
• Foams outperforms sphere beds in terms of reaction and mass transfer rates.

The scope of this work was to study the performance of a foam packed bed reactor for homogeneous wet oxidation of phenol, a relevant gas–liquid reaction in industrial wastewater treatment. The use of open-cell foams, macroporous structures constituted by interconnected channels with high bed porosity and surface area, largely enhances interfacial mass transfer rates, without significantly increasing pressure drop.Phenol (45 mol/m3) was oxidized in the aqueous phase by oxygen dissolved from the gas (6 bar), using Cu(II) salt (0.44 mol/m3) as homogeneous catalyst. Experiments were performed in a continuous reactor with partial liquid recycle. The fresh feed and total reactor flow rates have been adjusted to obtain different space times (395–1177 s) and liquid superficial velocities (0.84–3.5 × 10−3 m/s). Temperature has also been varied within the range 110–140 °C. Experimental phenol conversions are compared to that obtained from a simple perfect mixing model. Finally, the performance of the foam has been compared to that of a random packing bed made of spheres.

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