Nickel-Based High-Entropy Intermetallic as a Highly Active and Selective Catalyst for Acetylene Semihydrogenation.

Acetylene semihydrogenation is a key technology for producing polymer-grade ethylene from crude ethylene. Ni-based catalysts are promising alternatives to noble-metals for this process. However, achieving high catalytic activity and selectivity remains a big challenge. We report a novel catalyst design based on high-entropy intermetallics (HEI), which provide thermally stable isolated Ni without excess counterpart metals and achieve exceptionally high performance. Intermetallic NiGa was multi-metalized to a (NiFeCu)(GaGe), where the Ni and Ga sites were partially substituted with Fe/Cu and Ge, respectively, without altering the parent CsCl-type structure. The NiFeCuGaGe/SiO 2 HEI catalyst completely inhibited ethylene overhydrogenation even at complete acetylene conversion, and exhibited five-times higher activity than other 3d-transition-metal-based catalysts. The DFT study showed that the surface energy decreased by multi-metallization, which drastically weakened ethylene adsorption.