Enhanced metal dispersion and hydrodechlorination properties of a Ni/Al2O3 catalyst derived from layered double hydroxides

An image-layered double hydroxides (NiAl–LDHs) precursor has been synthesized in the pores of spherical γ-Al2O3 particles. After calcination at 500 °C, a NiO/γ-Al2O3 catalyst precursor was obtained. X-ray photoelectron spectroscopy, temperature programmed reduction, and temperature programmed desorption of hydrogen showed that in the material prepared by calcination of NiAl–LDHs supported on Al2O3, the NiO was characterized by higher reduction temperature, stronger interactions with Al2O3, and higher nickel dispersion compared with the NiO in a material prepared by conventional impregnation of γ-Al2O3 with an aqueous solution of Ni2+ ions followed by calcination at 500 °C. The vapor phase hydrodechlorination of chlorobenzene using molecular hydrogen was studied using Ni/γ-Al2O3 catalysts prepared by reduction of the NiO/γ-Al2O3 catalyst precursors synthesized by the two different methods. Under identical reaction conditions, the Ni/γ-Al2O3 catalyst obtained from the LDHs precursor exhibited not only higher activity but also better stability.