Using citrate-gel method to fabricate Ru-Fe-N catalyst for ammonia synthesis Li Shao 1 , Angela Daisley 2 , Justin S.J. Hargreaves 2 and Andrew L. Hector 1 1 University of Southampton, UK, 2 Glasgow, UK Iron (Fe)- and ruthenium (Ru)-based catalysts are the most efficient catalysts in ammonia synthesis. Here, a series of ternary metal nitrides Ru-Fe-N catalysts for ammonia synthesis are fabricated by using a citrate-gel approach followed by ammonolysis. 1 The chemical composition (Ru:Fe=0.6-1.6:3), ammonolysis temperature (400-900°C) and time (12 h and 24 h) were controlled to investigate their molecular structures and catalytic performances. The catalysts were characterised by XRD, SEM, EDX and CHN combustion analysis. The XRD patterns of the prepared Ru-Fe-N catalysts correspond to hexagonal Fe 3 N, the ruthenium atoms could replaced the iron atoms in the structure as there are ruthenium observed by EDX. CHN combustion analysis shows that low ammonolysis temperature (500 °C) contributes to higher nitrogen content in the materials while high ammonolysis temperature (900 °C) leads to low nitrogen content. Nitrogen content evaluated by CHN analysis was 4.55 wt.% for ammonolysis at 500 °C and 2.69 wt.% ammonolysis at 900 °C, the theoretical value is 4.94 wt.% for RuFe 3 N. These ternary metal nitrides show ammonia synthesis activity at low temperature (200-300 °C) and ambient pressure. RuFe 3 N ammonolysis at 900 °C was found to be inactive for ammonia synthesis at 200 °C.The XRD reflections have shifted to higher 2θ values after post-reaction which was probably caused by the catalysts losing nitrogen during the generating ammonia. The real mechanism will need further investigation. References 1. Samia Al Sobhi et. al ,Dalton Trans., 2019,48, 16786-16792.
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