Selective Alkylation of Phenol with Cyclohexanol over Large-Pore Zeolites

The alkylation of phenol with cyclohexanol has been investigated in the liquid phase without solvent over the H forms of various zeolites in the temperature range 140–220°C. Large-pore zeolites have been shown to be efficient catalysts in such a reaction, and led to the selective formation of para-cyclohexylphenol at higher temperatures. The product selectivity was found to be less dependent on the type of the zeolite structure in the case of large-pore zeolites. A maximum of about 85% for the phenol conversion has been obtained over H-Y and H-mordenite zeolites at 200 °C whereas the conversion is about 72% with H-β. The production of o-alkylated phenol is favored at lower temperatures and p-alkylated product at higher temperatures. The best operating temperature is 200 °C.