Dialkylation of naphthalene with isopropanol over acidic zeolites - Influence of pore structure on selectivity

The liquid phase alkylation of naphthalene with isopropanol has been studie d over various large pore zeolites with intermediate aluminum content. Whil e H-Y zeolite exhibits the best activity. and shows a high selectivity in 2 ,6- and 2,7-diisopropylnaphthalenes, in agreement with previous studies, H- Beta displays a peculiar behavior under the same conditions. The latter pro duces little diisopropylnaphthalenes; instead, a series of unexpected compo unds. consisting of (cyclopentyl)naphthalene derivatives (so-called cycliza tes), are formed in high yields. H-Mordenite, which features low activity, also demonstrates such an unexpected behavior towards formation of multialk ylated products. The results obtained over H-Beta are more particularly rep orted, and the identification of the cyclizates is confirmed. A mechanism i s proposed to explain the formation of these compounds depending on the var ious catalytic materials used, and the impact of the pore structure on acti vity and product distribution is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.