Scientists have found a cleaner way to produce ammonia from rare-earth metals, which works well at room temperature and pressure. The process, known as the Haber-Bosch process, involves using catalysts made from rare-earth metals to efficiently convert nitrogen into essential products such as pharmaceuticals, agrochemicals, and other fine chemicals under ambient conditions.

Ammonia could be used as a future carbon-free replacement for fossil fuels in vehicles. But, synthesizing it from molecular nitrogen is often an energy-intensive process.

In a recently published study, scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) found that employing catalysts made from abundant rare-earth metals can achieve the same reaction results at room temperature.

The study introduces new catalytic systems capable of reducing and functionalizing atmospheric nitrogen to valuable chemical products, expanding the understanding and capabilities of nitrogen fixation chemistry. The discovery of distinct mechanistic pathways for N₂ reduction and functionalization, particularly involving zirconium and lanthanides, opens up new avenues for research in the field of catalysis.

“Our catalysts activate and hold the dinitrogen, while different reagents come in and react to form different products,” says Polly Arnold, senior staff scientist and director of the Chemical Sciences Division at Berkeley Lab. She intends to use electrodes instead of the potassium reagent as a source of electrons since these can be renewable if they derive from solar cells.

The research work also contributes to advancing the field of dinitrogen chemistry by providing insights into the roles of different metal centers and ligand environments, which can inform the design of more efficient and selective catalysts.

By demonstrating catalytic systems that could potentially use electrochemical sources of electrons, the research points toward more sustainable and environmentally friendly methods of chemical synthesis.

Earlier this year, researchers from the University of Adelaide found a way to successfully split seawater to produce green hydrogen, which is also useful for ammonia synthesis.

Under the Indian government’s pilot projects for leveraging green hydrogen in shipping, green ammonia will be utilized for existing ocean-going and inland waterways vessels.