Benzene Hydroxylation and Simultaneous Extraction of Phenol in Two Membrane Contactors Made with Three-Compartment Cells

Two different three-compartment membrane contactors [called solid membrane contactor (SMC) and liquid membrane contactor (LMC)] were tested in the synthesis and separation of phenol produced by direct hydroxylation of benzene using a Fenton reaction. Phenol produced in the aqueous reacting phase was extracted in the organic phase and simultaneously stripped in the basic aqueous phase. Preliminary tests on phenol recovery evidenced better performances (86.5% of phenol recovered in the strip phase) using the SMC with 0.1 M Na<sub>2</sub>SO<sub>4</sub> in the aqueous feed phase at 35 °C. In the tests of partial oxidation, higher phenol productivity (0.62 g<sub>ph</sub> g<sub>cat</sub><sup>–1</sup> h<sup>–1</sup>) was obtained in this last system because the high phenol flux away from the reacting phase permitted one to extract a high amount of phenol in the organic and aqueous (strip) phases. This extraction protected phenol by its subsequent oxidation. It was evidenced that the use of a third compartment containing an alkaline aqueous stripping phase permitted one to recover phenol at 100% purity.