Facile Synthesis of Palladium‐Silver Dilute Alloy Catalyst for Acetylene Hydrogenation

Abstract

Selective hydrogenation of acetylene (C2H2) to ethylene (C2H4) has been recognized as an important strategic reaction for the removal of trace acetylene from ethylene. Palladium‐based alloys are one of the most commonly used catalysts for this reaction but bear a high price and unsatisfactory catalytic performance. Here, we develop a feasible strategy toward the synthesis of a palladium‐silver dilute alloy catalyst (PdxAg/Al2O3), which contains the Pd1Ag single‐atom‐alloy (SAA) and Pd2Ag dimer‐alloy (DA) species. This catalyst exhibits a high ethylene (C2=) yield of 90.1 % even after 100 hours at 60 °C, which is 11.9 times higher than that of the PdAg/Al2O3 alloy catalyst. Based on in‐situ spectroscopic investigations and theoretical calculations, both Pd1Ag SAA and Pd2Ag DA species in PdxAg/Al2O3 are easier to desorb C2H4 compared with PdAg/Al2O3, and they experience the possible hydrogenation paths with the low energy barriers to yield C2=. Furthermore, PdxAg/Al2O3 is beneficial to restraining coking due to the endothermic C−H bond cleavage. Thus, these combined merits contribute to the superior catalytic performance for PdxAg/Al2O3.

Effect of Bystander Hydrogen Atoms on Hydrogen Desorption on Single-Atom Alloy Surfaces: Insights from Simulated Temperature-Programmed Desorption Spectra

“…Single-atom alloy (SAA) catalysts, in which a reactive metal element is atomically dispersed in another relatively inert metal host, not only exhibit unique and excellent catalytic properties but also maximize the efficiency of atom utilization. − Due to the simplicity and clarity of their structures − and the well-established preparation methods, − SAAs provide an ideal platform for combining simulations and experiments to jointly elucidate microscopic processes and underlying mechanisms. ,− The SAA catalysts have been widely used in heterogeneous hydrogenation ,− and dehydrogenation ,− reactions. A thorough study of the interaction patterns between SAA surfaces and adsorbed molecules as well as the related elementary surface processes is of great importance for establishing the corresponding structure–property relationship. , …”