Selectivity control of benzene conversion to phenol using dissolved salts in a membrane contactor

Effect of salts, pH, type of acids and anion sulphate in the synthesis and separation of phenol through the hydroxylation of benzene by using a Fenton reaction in a biphasic membrane contactor has been investigated. The results indicated that sodium sulphate (1 M) increased phenol extraction in the organic phase (76.3%) but also increased reaction kinetics promoting over-oxidation products and a black solid (tar) formation. The acids delayed and in some tests avoided the tar appearance as precipitate but also gave a reduction of phenol selectivity. The sulphate absence, obtained by using iron(0), did not avoid the precipitate formation but only caused its decrease favouring a significant increase of the ratio productivity/amount of black solid from 4.6 to 62.4.

Figure optionsDownload high-quality image (100 K)Download as PowerPoint slideResearch highlights▶ Dissolved salts increased the amount of phenol extracted in the organic phase. ▶ Dissolved salts decreased selectivity, yield and productivity. ▶ The sulphate anion increased phenol degradation increasing tar formation. ▶ Fe(0) catalyst increased the ratio phenol productivity/amount of black solid.