ABSTRACT
Alkylations of phenol using tert-butyl alcohol (TBA) have been studied extensively owing to industrial interest in the production of antioxidants, ultraviolet absorbers and beat stabilizers for ~lymeric materials. The catalysts to date include liquid acidsl'-31, metal oxides~~. aluminum salt catalysts17·81and cation exchange resins19-131. Although cation exchange resin catalysts have some advantage over other catalysts, e.g. reducing equipment corrosion and no environmental pollution, they still possess some disadvantages. Their activity and the selectivity are not up to the rnark19-'3l. Changing over to zeolites instead of using environmentally hazardous catalysts is more acceptable, because of their activity, selectivity and re-usability. Phenol tert-butylation has not been studied in detail over zeolite catalysts, except for a few papers r:T.!rting the reaction over zeolite and SiOrAh03 catalyst in gas or liquid phase11 "161. Corma et al.1141 studied the influence of acid strength of zeolite HNaY catalyst on the tert-butylation of phenol with tert-butyl alcohol at 303, 318 and 353K in CC4 solutions. Their work reveals that C-alkylation requires stronger acidity than 0alkylation. Kijiya et at.1'6l studied the effect of acidity of various catalysts (SiOrAh03, Ah03, Zeolite X) on the reaction by using a continuous flow reactor under normal pressure at 455-523K. Our previous work1171 reveals that zeolite H!3 is an effective catalyst for tert-butylation of phenol giving high
• Correspondence to : Dr. Kui Zhang, Energy & Global Change, ABB Corporate Research Ltd., CH-5405 Baden-Dattwil, Switzerland. Tel. (+41) 56 48 670 81, email: kui.zhan-g@ch.abb.com
194 Zhangetal.
