Identification of Intermetallic CoSb as a Cost-Effective and High-Performance Catalyst for Acetylene Semihydrogenation

Designing high-efficiency and cost-effective catalysts for acetylene semihydrogenation holds significance for the production of polymer-grade ethylene in the chemical industry but remains difficult. In this study, we demonstrate an efficient synthesis of the CoSb intermetallic catalyst achieved through the in situ capture of molten Sb by Co, aiming to identify the Co-based catalysts for acetylene semihydrogenation. Combined investigations using X-ray diffraction, aberration-corrected high-resolution scanning transmission electron microscopy, and X-ray absorption spectroscopy demonstrate the presence of the pure CoSb intermetallic phase in the synthesized CoSb catalyst. The CoSb intermetallic catalyst, with a well-defined atomic arrangement and fine-regulated electronic properties, delivers 94.0% ethylene selectivity at ∼100% acetylene conversion. Temperature-programmed experiments and in situ spectroscopic studies, combined with theoretical calculations, unravel that the good hydrogenation performance arises from the moderate σ-binding of acetylene and easy desorption of ethylene on the fine-tuned Co active sites by Sb. These insights would be valuable for the creation of high-efficiency catalysts for acetylene semihydrogenation and potentially for other alkynes as well.