Chemoselective Hydrogenation of Nitroarenes Using Ni−Fe Alloy Catalysts at Ambient Pressure

Ni−Fe alloy catalysts have been used to achieve high activity and selectivity toward the hydrogenation of nitroarenes to aminoarenes. 4‐Nitrostyrene hydrogenation using a series of Ni‐based bimetallic alloys and intermetallic compounds supported on SiO 2 revealed that Ni−Fe alloy catalysts exhibit higher Turnover frequency (TOF) than Ni monometal catalysts with almost similar nanoparticle size. Furthermore, nitro‐selective hydrogenation under atmospheric hydrogen was observed, which has never been reported using conventional Ni catalysts. XRD and XAFS measurements revealed that both Ni and Fe were reduced to their metallic states by pretreatment under hydrogen flow at 400 °C. Kinetic experiments suggested that the formation of Ni−Fe alloy promoted the adsorption of the nitro group and suppressed the hydrogenation of the vinyl group. TOF and selectivity for 4‐nitrostyrene hydrogenation increased by reducing nanoparticle sizes, indicating that the metal–support interfaces interacted with 4‐nitrostyrene. Theoretical calculations suggested that the addition of Fe enhanced the co‐adsorption of dissociated hydrogen and the nitro group.