A hybrid nanocomposite precursor route to synthesize dispersion-enhanced Ni catalysts for the selective hydrogenation of o-chloronitrobenzene

Abstract

Highly-dispersed Ni nanoparticles over carbon nanotubes (CNTs) were successfully prepared from a hybrid nanocomposite of Ni–Al layered double hydroxide (NiAl-LDH) and poly acrylic acid (PAA) functionalized CNTs. The physicochemical properties of materials were investigated by powder X-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed desorption (TPD), transmission electron microscopy (TEM), low-temperature nitrogen adsorption–desorption experiments and X-ray photoelectron spectroscopy (XPS). The results revealed that L-cysteine as a bridging linker could facilitate the immobilization of NiAl-LDH crystals onto the surface of functionalized CNTs, thus giving rise to the dispersion-enhanced Ni nanoparticles with a small diameter of about 6.0 nm and narrow size distribution in the range of 3–7 nm. Compared with that prepared by the conventional impregnation method, the as-prepared supported Ni catalyst exhibited superior catalytic performance in liquid phase selective hydrogenation of o-chloronitrobenzene to o-chloroaniline along with the highest yield of 98.1% in 150 min, owing to its higher dispersion as well as the existence of both the electron-rich support and electron-deficient metal species.