Direct benzene conversion to phenol in a hybrid photocatalytic membrane reactor

The one-step conversion of benzene to phenol in a photocatalytic membrane reactor (PMR) coupling simultaneous reaction and product separation by means a membrane contactor is reported. The effects of parameters such as pH of aqueous TiO2 suspensions, initial amount of benzene and catalyst concentration were investigated in the batch tests. L–L extraction experiments and transport tests, using benzene as organic extractant, showed a phenol distribution coefficient of 2.1 and an extraction percentage of 24 ± 2%, assuring, also, a constant feed of substrate in the reactive environment. Phenol production and separation was carried out in the PMR investigating the influence of pH and catalyst concentration on the performance of the system. Despite a negligible difference on the phenol flux in the benzene phase (1.16 ± 0.11 mmol h−1 m−2), a better control of formation and extraction of oxidation intermediates at pH of 3.1 was obtained. To enhance the performance of the system, photocatalytic experiments with dissolved ions (Fe3+, Cu2+ and V3+) were carried out. The results showed a positive effect in presence of iron(III) ion with a phenol flux in the organic phase almost two times greater than those measured without salts.