Understanding Trends in Ethylene Epoxidation on Group IB Metals

Ethylene epoxidation is an industrially vital reaction to produce ethylene oxide (EO), which is usually hindered by the competing acetaldehyde formation and the subsequent combustion. So far, Ag-based materials are the most effective catalysts for the reaction, which have been extensively studied over the past decades. However, many fundamental questions are still under debate. In this paper, using density functional theory calculations, scaling relation analysis, and microkinetic modeling, we provide understandings of several open questions for ethylene epoxidation, including why Ag is the best catalyst compared to other group IB metals such as Cu and Au. Our model indicates that the answers to these questions originate from the moderate O-bonding and weak C-bonding strengths on Ag surfaces, leading to relatively high ethylene conversion and EO selectivity.