University of Bonn Team Develops Haber-Bosch Ammonia Alternative

Researchers at the University of Bonn have demonstrated a renewable-energy-based alternative to the Haber-Bosch process for ammonia production, offering the potential to reduce greenhouse gas emissions from one of the most energy-intensive industrial chemical reactions.

The approach, published in Nature Communications, uses water as a direct hydrogen source and electric power from renewable sources to synthesize ammonia (NH₃) from nitrogen gas (N₂).

The Haber-Bosch process, developed in the early 20th century, binds nitrogen from the air to hydrogen under high pressure and temperatures of up to 500 °C using an iron-based catalyst. While it enabled large-scale fertilizer production, it also relies heavily on fossil fuels—primarily methane—making it a significant contributor to global CO₂ emissions.

The University of Bonn research team, led by Prof. Dr. Nikolay Kornienko of the Institute of Inorganic Chemistry, adapted the lithium-mediated nitrogen reduction reaction (LiNRR) to operate with hydrogen sourced directly from water. In the LiNRR process, lithium ions are reduced to metallic lithium, which then reacts with nitrogen to form lithium-nitrogen compounds. When hydrogen is introduced, these compounds are converted to ammonia, regenerating the lithium ions for continuous operation.

To address the limitations of existing LiNRR systems—including the need for anhydrous conditions, low energy efficiency, and dependence on alcohol-based hydrogen donors—the team introduced a palladium (Pd) foil electrode. This material acts as both an electrode and a hydrogen-permeable membrane, separating the water-based hydrogen source from the anhydrous reaction environment. Hydrogen atoms generated from water electrolysis pass through the Pd membrane and react directly with the lithium-nitrogen compounds, producing ammonia without sacrificing alcohol or solvent molecules.

The method was validated using isotope tracing experiments with deuterium (D), confirming the hydrogen’s origin. While the approach remains in the early stages and current yields must increase by a factor of 1,000 for industrial viability, the team has filed a patent for the process. The research was supported by the German Research Foundation (DFG) and the University of Bonn’s Open Access Publication Fund.

About the University of Bonn

Founded in 1818, the University of Bonn is a leading German research institution recognized for its excellence in science, technology, and interdisciplinary studies. The university is home to multiple clusters of excellence and hosts internationally renowned research programs in chemistry, sustainability, and renewable energy innovation. For more information, please click here.

Source: University of Bonn

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