Explorative Study of a Ru/CeO2 Catalyst for NH3 Synthesis from Renewable Hydrogen and Demonstration of NH3 Synthesis under a Range of Reaction Conditions

The potential of Ru/CeO2 catalysts to catalyze the synthesis of ammonia from renewable hydrogen was explored under ambient and high-pressure conditions. Different types of Ru precursors, CeO2, and their combinations strongly influenced NH3 synthesis activity. The catalytic activities of Ru(acac)(3) and Ru(NO)(NO3)(3) were relatively high at ambient pressure. The activity of 1 wt% Ru/CeO2 with Ru(NO)(NO3)(3) as a Ru precursor was studied at high pressure. The dependence of NH3 synthesis activities on temperature, pressure, space velocity, and H-2/N-2 ratio were investigated. The parameter dependences differed somewhat between different types of CeO2. Use of CeO2 with high surface area resulted in relatively high NH3 synthesis rates and good low-pressure activity. Demonstration of NH3 synthesis using the optimized Ru/CeO2 catalyst was performed with a benchscale plant with the recirculation of unreacted gases. NH3 synthesis activity was measured using more than 130 combinations of temperature, pressure, space velocity, and H-2/N-2 ratio. NH3 concentrations in the product gases were close to equilibrium value for the reaction conditions around 400 degrees C. The effects of operation load on the response of NH3 production was acceptable. Ru/CeO2 catalysts are good candidates for industrial NH3 synthesis from renewable hydrogen.

Automated summary

Ru/CeO2 catalysts have potential for catalyzing the synthesis of ammonia from renewable hydrogen, with different Ru precursors and types of CeO2 influencing the activity. The optimized Ru/CeO2 catalyst showed good activity at high pressure, with CeO2 with high surface area resulting in higher synthesis rates. The effects of operation load on NH3 production were acceptable.