The effect of the H<sub>2</sub>:N<sub>2</sub> pre-treatment and reactant ratio upon the ammonia synthesis performance of the Ni<sub>2</sub>Mo<sub>3</sub>N catalyst

ASLAN M. Y., Daisley A., Hargreaves J. S. J.

CHEMICAL PAPERS, vol.79, no.6, pp.3633-3642, 2025 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 79 Issue: 6
  • Publication Date: 2025
  • Doi Number: 10.1007/s11696-025-04020-9
  • Journal Name: CHEMICAL PAPERS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core
  • Page Numbers: pp.3633-3642
  • Keywords: Ammonia synthesis, Ternary nitrides, Ni2Mo3N
  • Uşak University Affiliated: Yes

Abstract

The ammonia synthesis reaction over Ni2Mo3N was carried out at 400 °C and atmospheric pressure. The effects of the H2:N2 ratio on both nitridation and the ammonia synthesis reaction steps were investigated. Analysis of Ni2Mo3N samples nitrided at different H2:N2 ratios was performed using XRD and elemental analysis. The surface characteristics of Ni2Mo3N were determined using H2-TPR. When Ni2Mo3N was nitrided under 3:1 H2:N2, it was observed that a lower hydrogen ratio of 0.5:1 H2:N2 during the catalytic test improved the performance slightly. It is believed that the H2 poisoning effect decreases at lower H2:N2 ratios. The highest ammonia synthesis activity was observed over a Ni2Mo3N catalyst when nitrided under 0.5:1 H2:N2 when ammonia synthesis reaction was performed using a 3:1 H2:N2 reaction mixture. The reason can be the presence of metallic Ni in the catalyst structure, which is believed to facilitate H2 spillover to reaction medium.