Acetoxylation of Olefins over Supported Palladium Metal and Salts Catalysts

Abstract

The acetoxylation of olefins in the gaseous phase over palladium metal and salts-active charcoal catalysts was studied using a fixed bed reactor. Palladium salts adsorbed on active charcoal are excellent catalysts for this reaction even in the absence of any usual redox reagents such as CuCl2. It was concluded that the reoxidation of reduced palladium is catalyzed by active charcoal in the presence of oxygen.In the case of acetoxylation of ethylene the main product was vinyl acetate for both catalysts, but in the case of propylene, allyl acetate, isopropenyl acetate and acetone were mainly produced over palladium salts-active charcoal catalysts, whereas allyl acetate was the only principal product over palladium metal-active charcoal catalyst. The difference in the product distribution between these catalysts supposedly indicates that propylene forms a π-complex with palladium salts to give allyl acetate and isopropenyl acetate which was hydrolyzed to form acetone and, on the other hand, that propylene forms π-allyl complex with palladium metal to give allyl acetate.The kinetics of acetoxylation of ethylene was studied with a differential reactor for both catalysts and the reaction scheme was proposed for each reaction system.