Computational insights into promoting effects of alkali metals, Re, and Cl for silver catalysts of ethylene epoxidation

The effects of Re oxospecies, Cl, and alkali metal (AM = Li, Na, K, Rb, Cs) promoters for silver catalysts of ethylene epoxidation are considered using the DFT approach. The formation of Ag-bound AMReOx surface complexes that affect the catalyst performance is demonstrated. The interplays between silver, alkali metals, and anionic promoters are discussed. The Li-based systems mostly affect the catalyst activity while other alkali metals additionally affect the selectivity towards ethylene oxide in a varying extent. The Rb dopant shows potential as a Cs substitute or co-promoter. The facile composition-performance descriptor comprising the correlation of the substrate binding energy and charge over oxygen atom is proposed. The results obtained can be used in the applied designing of Ag-based epoxidation catalysts.