Highly Active and Stable Multifunctional Low-Pressure Ammonia Synthesis Catalyst

The Haber process for synthesis of ammonia is one of the most studied and important reaction of the last century. Ammonia is used mostly as a feedstock for fertilizer, but has gained considerable interest as a hydrogen carrier in a future hydrogen economy owing to
its specific energy content and ease of transportation. The Haber process, however, is a highly polluting, dangerous, and energy intensive process requiring 400-500°C and 100 bar. There have therefore been significant efforts towards designing a stable catalyst which can produce ammonia at significantly lower pressures. This will allow for ammonia production to be distributed, easier to make, and safer. To test these catalysts, the academic world has done most of their tests at 0.1MPa (1atm), not because the ultimate process would be done at such a pressure, but instead to give a universal benchmark for comparison between catalysts.
The catalyst the performed the best at 0.1MPa should also be the best at 1MPa owing to the nature of the reaction. When comparing low pressure ammonia synthesis catalysts, the figures of merit are typically the rate of ammonia production and the amount of ruthenium used.
Our patented trimetallic FeCuRu catalyst has been synthesized in such a way that 2 nm Ru-Fe alloying provides active sites and 2nm Cu particles provides the necessary macrostrain to promote electronic/ionic mobility. Cu is also be investigated for its role for H2 spillover on adjacent Ru-Fe sites whereby increasing the activity. Importantly, the unique insolubility of these three metals means that they remain largely unalloyed and unagglomerated on the surface. In this sense, particles are anchored to the ceramic support and cannot agglomerate (even at high temperatures over very long timescales) since each particle presents a geometric diffusion barrier, thereby restricting agglomeration. Our FeCuRu catalyst can produce 7.5 mmol NH3/gcat/h with <1 wt.% Ru at 0.1MPa and 400° C. (> 0.75 mol NH3/gRu/h)
The synthesis process is easy and scalable. We are therefore looking for strategic partners to help us in validating and commercializing our catalyst for low-pressure (3-6 bar) ammonia synthesis.

Figure 1: The unique nanostructure of the FeCuRu
ammonia synthesis catalyst

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