Ethylene epoxidation over silver and copper-silver bimetallic catalysts: II. Cs and Cl promotion

Copper-silver bimetallic catalysts offer improved selectivity relative to silver in the direct epoxidation of ethylene, as predicted by density functional theory calculations. The performance advantages of bimetallics over silver have been shown previously for unpromoted, monolith-supported catalysts. Here we demonstrate that the higher activity and selectivity of Cu-Ag bimetallic catalysts prepared by sequential impregnation are maintained when conventional promoters, such as cesium and/or chlorine, are used. Selectivities to ethylene oxide obtained for promoted bimetallic catalysts were up to 15 points higher than those obtained for promoted silver catalysts at comparable conversions. (c) 2005 Elsevier Inc. All rights reserved.