Catalysts Derived from Al–Ni Intermetallic Compounds for Efficient Selective Semihydrogenation of Phenylacetylene

Using the low-temperature molten salt strategy, Al–Ni intermetallic compound catalysts (AlNi, Al3Ni2, and AlNi3) with efficiently separated nickel sites are successfully prepared by reducing the oxides of stoichiometric mixtures of the corresponding elements. Applying these materials as catalysts in the semihydrogenation of phenylacetylene to styrene suggests that the AlNi3-derived catalyst exhibits superior catalytic performance, achieving a remarkable styrene selectivity of 88% at a high conversion of phenylacetylene (99%). In conjunction with reaction kinetics, in situ infrared (IR) measurements, and density functional theory (DFT) calculations, the electron-rich Ni active center, created through electron transfer from Al atoms, plays a pivotal role in reducing the surface adsorption energy of styrene and thus enhancing the semihydrogenation selectivity. In addition, the magnetic AlNi3-derived catalysts exhibit excellent stability and can be easily separated by using a magnet.