Chemical kinetics of hydroxylation of phenol catalyzed by TS-1/diatomite in fixed-bed reactor

The chemical kinetics of hydroxylation of phenol with 30% H2O2 over the TS-1/diatomite catalyst in a fixed-bed reactor system was studied at 50–90 °C. The rate of hydroxylation of phenol was found to increase with increase in temperature, phenol and hydrogen peroxide concentrations. Simultaneously, the rate of decomposition of hydrogen peroxide also increased with increase in temperature and hydrogen peroxide concentration. Based on our analysis, the consuming rate of phenol, formation rate of catechol and hydroquinone and the rate of decomposition of hydrogen peroxide can be described as: rP=7.18×103 e−(42.0/RT)CP1.06CH2O20.34, rCAT=3.92×103 e−(42.1/RT)CP1.09CH2O20.33, rHQ=3.13×103 e−(41.9/RT)CP1.04CH2O20.35 and rH2O2=1.75×107 e−(57.8/RT)CH2O20.75, respectively. Based on the Eley–Rideal mechanism for an adsorption of single molecule, the reaction kinetic model of hydroxylation of phenol has been founded, that is r=(kK1CH2O2CP)/(1+K1CH2O2+K2CP+K3CProd)r=(kK1CH2O2CP)/(1+K1CH2O2+K2CP+K3CProd), which is in agreement with the experimental data.