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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