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.