Origine de la désactivation d'une zéolite HY désaluminée au cours de la synthèse d'hydroxyacétophénones

Hydroxyacetophenones are produced from phenylacetate or equimolar mixtures of phenylacetate and water or phenol and acetic acid at 400 o C on a dealuminated HY zeolite (Si/Al=15). This reaction is accompanied by the rapid formation of secondary heavy products. These products remain blocked in the zeolite pores because of their great polarity are responsible for the rapid deactivation of the zeolite. Adsorption of nitrogen or n-hexane on deactivated zeolites shows that the deactivation is essentially due to the blocking of the access to the active sites of reactants. However, the more pronounced deactivation that occurs when pure phenylacetate is used as reactant is due to the dehydroxylation of the zeolite with transformation of phenylacetate into phenol and acetic acid