Acylation of toluene with acetic anhydride over beta zeolites:: Influence of reaction conditions and physicochemical properties of the catalyst

Acylation of toluene with acetic anhydride was carried out over Beta-type zeolites in a stainless steel autoclave. At low temperature, i.e., 150 degrees C, and an arene/anhydride molar ratio 10-20, high yields of 4-methylacetophenone were obtained with selectivity close to 100%. The reaction is limited by the poisoning of the active sites by adsorption of the product and pore blockage due to "coke"-type products. Acid site accessibility is of paramount importance for this reaction, and the use of a nanocrystalline Beta zeolite as catalyst minimizes catalyst decay. This, combined with an optimum framework composition, allows the preparation of active and selective acylation catalysts based on Beta zeolite. (C) 2000 Academic Press.