Insights into coverage-affected selective catalytic oxidation of ethylene on Ag(111) from comprehensive microkinetic analyses

Abstract

Ethylene epoxidation is one of the most critical industrial reactions. Although there have been many studies on the reaction, the details of the reaction kinetics remain elusive. In this work, an extensive microkinetic modelling based on DFT calculations was conducted to study ethylene epoxidation on Ag(111). Coverage-dependent and coverage-independent microkinetic modellings were performed with rigorous energetics calculated on adsorption and transition states. The detailed comparisons between the two modellings show that the coverage-independent modellings are inadequate even though the coverage is very low at the steady state. It is also found that the activity and selectivity trends from the coverage-dependent modelling are consistent with the experimental values under the experimental conditions. A comprehensive kinetic analysis under industrial conditions was conducted based on the coverage-dependent modelling, which shows that increasing the temperature and pressure can effectively enhance the activity and ethylene epoxide (EO) selectivity.