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Abstract

Effect of promoters on vinyl acetate (VA) synthesis has been studied using a fixed bed reactor with oxidation reaction of ethylene and acetic acid in gaseous phase over Pd-Au/SiO2 catalyst with a surface area of 600 m2/g. detailed analysis of changes in selectivity and ethylene conversion with respect to different alkali metallic acetate promoters are investigated and it is concluded that such promoters are observed to stabilize the catalyst surface. While alkali based acetates were found to have the uttermost impact, an increase of primitive effect was discovered from the top to the bottom of the first column elements of the periodic table implemented in promoters. It is further deduced that the promoting effect is due the common-ion effect of acetate, present in the reaction, resulting in an increase in the activity of the catalyst. In addition a complementary theory for the effect of Au in the structure of the catalyst is proposed suggesting the imposition of distribution of palladium particles through decreasing the particle’s diameter.