Structure and catalytic properties of Ni/MWCNTs and Ni/AC catalysts for hydrogen production via ammonia decomposition

• Catalytic performance of ammonia decomposition depended on carbon support material.
• Ni dispersion was correlated with the surface area of AC used for Ni/AC catalyst.
• The TOFNH3 is a function of Ni particles size of Ni/AC catalysts.
• Ni/MWCNTs catalyst exhibited a much higher catalytic activity than Ni/AC catalysts.

The structure and catalytic properties of nickel catalysts supported on multi-wall carbon nanotubes (MWCNTs) and on three different types of activated carbon (AC) were studied. The surface areas of AC carriers were defining the size of supported nickel particles. Large surface area of AC led to small Ni nanoparticles and high Ni dispersion. Turnover frequency (TOFNH3) of ammonia decomposition decreased with decreasing of Ni particle size. The highest degree of ammonia conversion was observed on Ni/AC prepared by using of AC support with largest surface area. The catalytic activity of Ni/MWCNTs was much higher than catalytic activity of the studied Ni/AC catalysts. The synergic nickel-support interaction and special electronic conductivity properties of MWCNTs were responsible for high catalytic activity of Ni/MWCNTs catalyst.