A practical approach to the treatment of adsorption-desorption isotherms, acidity and catalytic behaviour of zeolite catalysts

The relationship between texture evaluated on the basis of nitrogen adsorpt ion-desorption isotherms, acidity and catalytic activity of mordenite catal ysts dealuminated to various extents and doped with cerium was investigated . The combination of the standard BET isotherm either with a consideration of the micropores, or with the Dubinin-Radushkevich isotherm proved to be a good tool for the estimation of the micropore volume and outer surface of the catalysts. A very good description of the surface of the micropores was obtained using the n-layer BET isotherm. SEM pictures of the catalysts rev ealed that the mesopores are probably located in the interparticle space be tween mordenite crystallites. The isopropylation of biphenyl was applied as a model reaction. Changes in the micro- and mesoporosity as well as change s in the acidity were invoked to account for the observed catalytic activit ies and selectivities for 4-isopropylbiphenyl and 4,4'-diisopropylbiphenyl. (C) 2001 Elsevier Science B.V. All rights reserved.