Effect of impregnation solutions on the synthesis of Ni-Cu/Al₂O₃ catalyst to obtain carbon nanofibers

The present work reports on the influence of nickel molar loading and impregnation solutions, nitrate salts and copper and nickel ammonium complexes, on the synthesis of Ni-Cu catalyst supported on alumina for obtaining carbon nanofibers by catalytic chemical vapor deposition of methane. These catalysts were characterized by N₂ adsorption-desorption, x-ray Diffraction, Thermo-Gravimetric Analysis and Scanning Electron Microscopy for the carbon nanostructures analysis. The catalytic activity was studied through the carbon deposition under different conditions of temperature (600 °C and 650 °C) and pressure (in ultra-low pressure conditions and 0.5 bar). As a main result, catalyst using nitrate salts impregnation leads to the major carbon nanofibers yielding at the temperature of 600 °C. On the other hand, catalysts synthesized by ammonium complexes impregnation present also improved characteristics compared to conventional catalysts that allows considering this methodology as an interesting alternative in carbon nanofibers producing.