(581g) Strong Metal-Support Interaction Effects on PdAg Alloy Nanoparticles: A Promising Approach for Acetylene Semi-Hydrogenation

Manipulating the interactions between precious metal nanoparticles and metal oxide supports is crucial for advancing heterogeneous catalysis. Specifically, the use of strong metal-support interaction (SMSI), which involves encapsulating group VIII metal nanoparticles with reducible metal oxides (such as TiO₂, Fe₃O₄) under H₂ at elevated temperatures, is an effective strategy for fine-tuning the activity, selectivity, and stability of nanoparticles. However, the SMSI effects on alloy nanoparticles have received little attention to date. To address this gap, we synthesized core/shell nanoparticles with a PdAg core wrapped by a FeO_x shell (denoted as PdAg/FeO_x) and triggered the SMSI effect by treating PdAg/FeO_x under H₂ flow at 300 °C (denoted PdAg/FeO_x-H). By employing atomic-resolution electron microscopy and X-ray absorption spectroscopy, we studied the SMSI effect on PdAg alloy and observed different behaviors between Pd and Ag atoms. Subsequently, we utilized PdAg/FeO_x-H nanoparticles for acetylene semi-hydrogenation into ethylene. Under a feed gas of 0.5% C₂H₂ in Ar, the PdAg/FeO_x-H exhibited >99% acetylene conversion and >95% ethylene selectivity at 130°C. We attribute the excellent selectivity towards ethylene to the SMSI effect, which created a special confinement and weakened C₂H₄ adsorption over the PdAg surface. In summary, our work opens the door for studying SMSI behavior over alloy nanoparticles and applying it to important reactions, including but not limited to, the hydrogenation of alkynes.