In situ synthesis of nickel carbide-promoted nickel/carbon nanofibers nanocomposite catalysts for catalytic applications

• Nickel carbide-promoted Ni/CNFs nanocomposites were in situ generated by CCVD.
• CNFs were produced along with the simultaneous formation of nickel carbide.
• High catalytic performance in hydrogenation of chloronitrobenzenes was achieved.
• Synergistic catalytic effect between Ni0 and nickel carbide was confirmed.

In the present work, nickel carbide-promoted nickel/carbon nanofibers nanocomposite catalysts (NiC-Ni/CNFs) were directly in situ generated by a facile catalytic chemical vapor deposition (CCVD). The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results showed that carbon supported nickel catalysts (Ni/C) could catalyze the growth of CNFs in CCVD, while nickel carbides were formed simultaneously under acetylene atmosphere and further successfully stabilized by uniform CNFs to form NiC-Ni/CNFs. This applied method did not need the pretreatment of multiple steps including the purification of CNFs and subsequent immobilization of active metallic nickel species. As-formed NiC-Ni/CNFs catalysts exhibited excellent performance in liquid phase selective hydrogenation of o-chloronitrobenzene to o-chloroaniline with a high yield of 96.6%, which was mainly attributed to a synergistic catalytic effect between metallic nickel and nickel carbide species. Furthermore, such nickel carbide-promoted Ni-based catalyst showed excellent catalytic performance in the selective hydrogenations of p- and m-chloronitrobenzenes to p- and m-chloroaniline.