FRIEDEL-CRAFTS CATALYSIS USING SUPPORTED REAGENTS - SYNTHESIS, CHARACTERIZATION AND CATALYTIC APPLICATIONS OF SOL-GEL-DERIVED ALUMINOSILICATES

Aluminosilicate catalyst supports have been prepared from aluminium tr i-sec-butoxide and tetraethyl orthosilicate in butanol using sol-gel m ethodologies, thereby providing useful supports for zinc chloride, to generate heterogeneous Friedel-Crafts alkylation catalysts. The optimu m loading for these sol-gel-derived materials is higher than that of K 10, the support for the commercially available catalyst 'Clayzic' and gives significantly higher catalytic activity in a standard test react ion. A more convenient, 'one-pot' approach, in which zinc chloride is added during the sol-gel synthesis, generates catalysts which also sho w significantly higher activity than Clayzic. The resulting materials have been characterized by Si-29 cross-polarization magic-angle spinni ng (CP-MAS) and Al-27 MAS NMR, IR spectroscopy and by surface area and pore volume analysis. The Si:Al ratio, drying temperature and relativ e amounts of water and (non-aqueous) solvent have pronounced effects o n catalytic activity. The most active catalysts show relatively high l evels of framework aluminium species compared with non-framework sites , and also have higher surface areas and pore volumes than materials w ith lower activity.