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 adsorption-desorption isotherms, acidity and catalytic activity of mordenite catalysts 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 revealed that the mesopores are probably located in the interparticle space between mordenite crystallites. The isopropylation of biphenyl was applied as a model reaction. Changes in the micro- and mesoporosity as well as changes in the acidity were invoked to account for the observed catalytic activities and selectivities for 4-isopropylbiphenyl and 4,4'-diisopropylbiphenyl. (C) 2001 Elsevier Science B.V. All rights reserved.