Physicochemical and catalytic properties of Zr-pillared montmorillonite with varying pillar density

Preparation, characterization and catalytic activity of Zr-pillared clays with different pillar density, starting from Ni2+ exchanged clay, are described. The physicochemical characteristics of the pillared clays have been evaluated using X-ray diffraction (XRD), thermogravimetric analysis (TGA), infrared (IR), UV-visible diffuse reflectance spectroscopy (UV-VIS-DRS) and sorptometric studies. The decrease in the cation exchange capacity (CEC) of the Ni2+ exchanged clay depends upon the pretreatment temperature. The migration of the Ni2+ ions into vacant octahedral sites was observed in IR spectroscopy. The acidity of the pillared clays was calculated from TG analysis of the adsorbed n-butyl amine. Alkylation of phenol with methanol was carried out over these catalysts. Good correlation was observed between the alkylation activity and acidity of the pillared materials. Both O and C-alkylation was observed during the reaction. The pillared materials with lesser pillar density were found to be more selective towards anisole which can be attributed to the control in acidic properties of the materials. (C) 2004 Elsevier Inc. All rights reserved.