| Popis: |
The effect of water on the activity and selectivity of the phenol hydroxylation reaction was examined. To do this, hydroxylation of phenol with H2O2 was performed over Al-free Ti-β with varying fractions of water in the methanol/water mixture being used as the solvent. . It was observed that while the activity was high in pure water, there was a lower, but unchanging activity between 7 and 26% water. This can be attributed to the dominating effect of methanol in the adsorption dynamics. The changing water content had a marked effect on the hydroquinone selectivity, with higher selectivity for hydroquinone observed at low water contents. The effect on selectivity is attributed to the competition between methanol and phenol to coordinate with the titanium hydroperoxo group. |
