Supported Pd–B alloy mesoporous nanospheres as efficient catalysts for nitrobenzene hydrogenation

In this work, fcc Pd–B alloy mesoporous nanospheres (MNSs) were synthesized and supported onto alumina (Pd–B/Al₂O₃) for catalytic hydrogenation of nitrobenzene to aniline, where Pd–B MNSs were prepared by a co-reduction method using dioctadecyldimethylammonium chloride as the surfactants and borane dimethylamine complex as reducing agents as well as B sources. Compared with alumina supported Pd MNSs, Pd–B/Al₂O₃ demonstrated a much higher hydrogenation activity. Under a nitrobenzene/Pd molar ratio of 2000/1, 0.1 MPa of H₂ and 45 °C, the yields of aniline could reach nearly 100% during 70 min. The improved catalytic efficiency originates from the synergistic effect between B and Pd, where alloying Pd with B enlarges the Pd–Pd distance and alters the geometric and electronic properties of surface Pd species, resulting in enhanced activities for nitrobenzene hydrogenation.