Palladium–silver bimetallic catalysts with improved activity and selectivity for ethylene epoxidation

Palladium addition to silver catalysts for ethylene epoxidation increases both catalyst activity and selectivity to ethylene oxide. These results confirm the predictions from density functional theory calculations that Pd–Ag bimetallics should improve selectivity relative to unpromoted silver. The performance of Pd–Ag catalysts is similar to that of Cu–Ag catalysts investigated previously, although the maximum selectivity obtained for the optimum Pd–Ag catalyst in the present study exceeds that achieved with Cu–Ag catalysts. Although there is evidence for greater complexity in the structure of these catalysts than has been incorporated in DFT models, these results provide an important additional example of catalyst identification and design from first principles.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (59 K)Download as PowerPoint slideResearch highlights▶ DFT calculations predict higher ethylene epoxidation selectivity for Pd–Ag catalysts. ▶ Pd–Ag catalysts with 100 ppm Pd show higher measured activity and selectivity. ▶ Performance of Pd–Ag catalysts is similar to Cu–Ag catalysts.