Effects of composition and production route on structure and catalytic activity for ammonia decomposition reaction of ternary Ni–Mo nitride catalysts

• Ni2Mo3N based catalysts were produced by hydrogen reduction from different mixed-salt precursors.
• The catalytic activity for ammonia decomposition was studied.
• The ammonia conversion increases with the increase of Ni2Mo3N phase content.
• The catalytic activity of nitrides was higher than the activity of iron based catalyst.

Ternary Ni–Mo–N systems with high (up to 82 wt. %) content of Ni2Mo3N phase were produced by means of hydrogen reduction of different complex metal containing precursors. The precursors were obtained by two production routes, viz. evaporation and co-precipitation, with using of different initial Ni-containing salts. The samples were characterized by x-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, low-temperature nitrogen adsorption, evolved gas analysis by mass-spectrometry. Catalytic activity of ternary Ni–Mo nitride catalysts for ammonia decomposition reaction at atmospheric pressure and different temperatures was determined. It was established that the composition of the precursor and its production route notably influenced the relative yield of the nitride phase and specific surface area of the products. The ammonia conversion vs. temperature plot was similar for nitride catalysts with onset at 400 °C and full conversion at 650 °C. It differed only at moderate temperatures in the range from 500 °C to 600 °C with the highest conversion rate for the sample obtained by evaporation route with using of nickel acetate as precursor. It was shown that the relative catalytic activity of all obtained nitride samples were substantially higher than the activity of iron containing catalyst used as the reference material.