Hydroxylation of phenol with H2O2 over Fe2+ and/or Co2+ ion-exchanged NaY catalyst in the fixed-bed flow reactor

The catalysts, Fe-NaY, Co-NaY and Fe-Co-NaY, were prepared by ion-exchange of NaY through the wet method, and characterized. Their catalytic performance was evaluated for the hydroxylation of phenol between 30 and 90 °C. The Fe-Co-NaY catalyst showed higher activity than either Fe-NaY or Co-NaY catalysts. The optimum temperature was found to be 70 °C. The reaction conditions, phenol/H2O2, water/phenol and WHSV, were found to remarkably influence the activity of the catalysts. Under the optimum reaction conditions, 21.8% phenol conversion was obtained with 44.8% selectivity to catechol, and 16.5% to hydroquinone. Based on the high phenol conversion over Fe-Co-NaY compared to Fe-NaY and Co-NaY catalysts, it was suggested that well-dispersed Fe with optimum loading was the requirement for high phenol conversion and products selectivity. The long-run catalytic test for 44 h confirmed the absence of leaching of metal ion from the pores of Fe-Co-NaY catalyst. The reaction was carried out in a fixed-bed flow reactor, which could be a convenient solution to the problem of the batch type reactor in industrial applications.

Graphical abstractThe hydroxylation of phenol with H2O2 was studied in an atmospheric fixed-bed flow reactor. At the reaction temperature of 70 °C, phenol/H2O2 molar ratio of 3, WHSV of 4 h−1, and water/phenol weight ratio of 4.5, the Fe and Co ion-exchanged NaY catalyst gave phenol conversion of 21.8%. The effective conversion of H2O2 was 56.6%, and the selectivity to catechol and hydroquinone was 44.8 and 16.5%, respectively. Figure optionsDownload full-size imageDownload as PowerPoint slide