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 gamma-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 degrees 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 Al2O3) 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.