ANION TREATMENT (F- OR SO42-) OF AIPO4-AL2O3 (25 WT -PERCENT AL2O3) CATALYSTS .4. CATALYTIC PERFORMANCE IN THE ALKYLATION OF PHENOL WITH METHANOL

Vapour-phase catalytic alkylation of phenol with methanol was carried out in a microcatalytic pulse reactor on AlPO4-Al2O3 catalysts, contai ning various amounts (1-3 wt.-%) of fluoride or sulfate anions. The me thylation reaction gave a mixture of O- and C-alkylated products (C-al kylation taking place preferentially at the ortho-position). The influ ences of the methanol/phenol molar ratios (0.5-8), the reaction temper ature (523-673 K) and both anion type and anion loading upon the conve rsion of phenol and the selectivities of the products were investigate d. The increase in surface acidity by anion loading (especially in the case of fluoride ion) increases both the O-alkylation selectivity (ma inly to anisole) and dealkylation processes; so that a lower phenol co nversion (smaller pseudokinetic constant) and higher anisole selectivi ty is found for anion-modified AlPO4-Al2O3 catalysts related to unmodi fied ones. From the distribution of methylated products and their OPE curves, an outline of catalyzed alkylation was presented.