CHARACTERIZATION OF CLAY-BASED K-CATALYSTS AND THEIR APPLICATION IN FRIEDEL-CRAFTS ALKYLATION OF AROMATICS

Toluene was alkylated with benzyl chloride and benzyl alcohol using a series of clays (KSF, KSF/0, K0, KP10, K10, KS from Sud Chemie) obtain ed by treating a bavarian bentonite by different acids and a Hungarian bentonite (Mad) as catalysts in a batch reactor. The catalysts were c haracterized by chemical analysis, thermal analysis, nitrogen adsorpti on, solid state nuclear magnetic resonance, X-ray diffraction. The aci dity of these solids was determined by infrared spectroscopy using pyr idine as molecular probe. The structure, specific surface area, and di stribution of Lewis/Bronsted acidity of these clays can be changed to a great extent by acidic or thermal treatment. The rate of alkylation is related to Bronsted acidity when the substrate is benzyl alcohol. W hen benzyl chloride is used as alkylating agent, the Fe3+ content of t he clay controls the activity, and iron containing clays show high act ivities in spite of their low Lewis acidities.