Cu Evolution over Bimetallic Cu-Y/Beta Zeolite Under H2 and Ethanol Atmospheres: Unveiling the Role of Diatomic Metal-Metal Interactions.

Abstract

Understanding the dynamic evolution of Cu species under varying environmental conditions is critical for addressing challenges related to the activity and the stability of copper-based catalysts in thermo-, photo-, and electrocatalysis. However, metal-metal interactions between dual single atoms and their effects on Cu evolution after exposure to different environmental molecules remain underexplored. Herein, we synthesized bimetallic Cu-Y/Beta catalysts with dual single-atom Cu and Y sites and monometallic Cu-Beta catalysts with isolated Cu sites in dealuminated Beta zeolites. By varying Cu and Y compositions, diatomic interactions were studied under H2 and ethanol atmospheres. With 6 wt% Y loading, approximately 0.4 wt% of Cu species in Cu-Y/Beta remained partially oxidized as Cu(I) after reduction in pure H2 at 350 °C, in contrast to the full transition to metallic Cu observed in Cu-Beta. Combining X-ray absorption spectroscopy with kinetic studies revealed that metallic Cu became the predominant species after reduction with H2 as Cu loading increased from 0.4 to 1.7 wt%, quadrupling the initial ethanol dehydrogenation rate and demonstrating the dominant role of Cu(0) sites. Scanning transmission electron microscopy and density functional theory simulations indicated spatial proximity between dual single-atom Cu and Y sites and elucidated Cu speciation controlled by diatomic interactions.