ABSTRACT
The activity/selectivity patterns of a HZSM-5 zeolite (Si/Al = 23) have been studied during the alkylation of phenol (PhOH) and halobenzenes (X-Bz; X= F, Cl, Br), with methanol. Reactions were carried out in a flow system with a fixed bed reactor at atmospheric pressure, 250 °C and a N2/reactants molar ratio of 4. Consecutive experiments were carried out in which phenol alkylation was followed by chlorobenzene alkylation and vice versa, in order to establish the poisoning effects of the reactants over the catalyst. The rate of phenol alkylation was higher than that observed for the three halobenzenes. Anisole and o- and p-cresols were the main products of phenol alkylation. Halotoluenes and haloxylenes were obtained from halobenzene alkylation. The results of the consecutive experiments show that phenol alkylation deactivates the catalyst for the chlorobenzene alkylation while the contrary was not observed, supporting the fact that in the phenol alkylation, deactivation of the catalyst is mainly due to a strong physical adsorption of phenol.
