Investigation of the Structure and Catalytic Performance of Highly Dispersed Ni-Based Catalysts for the Growth of Carbon Nanostructures

The in situ growth of Ni-containing layered double hydroxide (LDH) microcrystallites on microspherical γ-alumina support was carried out through the surface activation of support followed by a homogeneous coprecipitation process, and carbon nanomaterials were synthesized directly over as-grown supported LDH samples via catalytic chemical vapor deposition of acetylene. As compared to that prepared by the conventional impregnation, supported LDH samples calcined at 700 °C possessed higher metal dispersion, which was attributed to well-developed two-dimensional structure of LDH platelets uniformly grown on the support surface originating from the strong interaction between brucite-like lattices and support. Furthermore, the supported catalyst from NiAl-LDH could catalyze the growth of regular carbon nanofibers, while another one from NiMgAl-LDH exhibited excellent catalytic performance for the growth of uniform carbon nanotubes due to higher metal dispersion achieved by the separating effect of amorphous metal oxide (MgO and Al 2 O 3 ) phases around Ni nanoparticles. As-synthesized supported Ni-based catalysts are promising for practical applications in the production of carbon nanostructures with uniform geometric shape.