Effect of H 2 :N 2 ratio on the nitridation and reaction conditions on NH 3 synthesis reaction over Ni 2 Mo 3 N Mustafa Aslan and Justin Hargreaves University of Glasgow, UK Ammonia production process consumes ca. 2% of energy production of the world annually and approximately 70% of the total cost of ammonia production is directly related with the cost of production of H 2 [1,2]. It is also the source of the 3% of the anthropogenic CO 2 production 3 . Therefore, a more sustainable way for producing ammonia is needed to decrease the carbon footprint and the cost of the production process. Molybdenum nitrides are getting attraction due to their stability, atomic nitrogen transfer ability and ammonia synthesis activity 4 . In this study, the effect of H 2 :N 2 flow ratio on both pre-treatment and reaction conditions on NH 3 synthesis reaction over Ni 2 Mo 3 N will be presented. Ni 2 Mo 3 N was synthesized using Pechini method and nitrided under H 2 :N 2 flow at 700 o C. Nitridation of the catalyst from oxide phase to nitride phase were performed with two different H 2 :N 2 ratios such as 3.0 and 0.5. While a pure phase of Ni 2 Mo 3 N was obtained when H 2 :N 2 ratio was 3.0, metallic Ni and γ-Mo 2 N impurities were observed in the XRD patterns of both fresh and spent Ni 2 Mo 3 N samples when H 2 :N 2 ratio of 0.5 was used. Ammonia synthesis activity tests were also performed under flow of different H 2 :N 2 ratios of 3.0 and 0.5 at 400 o C. The ammonia synthesis rate was measured as 117 μmol NH 3 g catalyst- 1 h -1 under flow of H 2 :N 2 ratio of 0.5 at 400 o C and atmospheric pressure and slightly higher with respect to when H 2 :N 2 ratio was 3.0. According to the characterization and reaction studies, ammonia synthesis reaction can be carried out with a lower H 2 :N 2 ratio with respect to stoichiometric ratio over Ni 2 Mo 3 N catalyst which means that may decrease the role of hydrogen in cost of ammonia production. References 1. N. Saadatjou, A. Jafari and S. Sahebdelfar, Chemical Engineering Communications, 202 (2015), 420 2. www.ammoniaenergy.org/articles/the-cost-of-co2-free-ammonia/ last accessed 16.01.2023 3. S. D. Minteer, P. Christopher and S. Linic, ACS Energy Letters, 4 (2019), 163 4. D. Mckay, D. H. Gregory, J. S. J. Hargreaves, S. M. Hunter and X. Sun, Chemical Communications, 29 (2007), 3051
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