Ni active sites isolated by antimony toward enhanced propyne semi-hydrogenation

Regulating Ni active sites toward the formation of target product is of great importance for designing high-performance cost-effective catalysts for catalytic semi-hydrogenations but remains challenging. Herein, we report the fabrication of NiSb intermetallic catalyst via structural transformation from a layered double hydroxides precursor for boosting propyne semi-hydrogenation. Systematic characterizations, including x-ray diffraction, atomic-resolution electron microscopy, and x-ray absorption spectroscopy, provide evidence for the formation of P63/mmc NiSb intermetallic phase in the synthesized NiSb catalyst. The host Ni active sites are demonstrated to be isolated by the high-electronegativity p-block guest Sb sites, which deliver remarkably high selectivity to target propene, that is, up to propene selectivity of 96% at nearly full propyne conversion. Temperature-programmed surface reaction and temperature-programmed desorption measurements combined with theoretical calculations unravel that the excellent selectivity originates from kinetically more favorable desorption of propene than its hydrogenation to propane on the regulated Ni active sites.