MIT computer models identify promising catalysts for low-emission ammonia production

Ammonia production currently consumes about 2% of global energy and generates roughly 1.5% of greenhouse gas emissions, almost entirely through the century-old Haber–Bosch process that relies on fossil fuels for heat and hydrogen. An electrochemical alternative exists but has not reached the production rates or cost competitiveness needed for industrial scale.

Researchers at MIT have developed a computational approach to accelerate the search for better catalysts, which are the key to making electrochemical ammonia synthesis viable. Rather than testing millions of possible alloys through trial and error, the team used density functional theory to simulate the quantum mechanical behavior of transition metal nitrides, a class of materials already known to be effective for nitrogen reduction reactions.

The study identified specific electronic descriptors — based on the hybridization between nitrogen 2p and metal d bands — that predict the energetics of the nitrogen reduction reaction. These descriptors reveal a band theory for efficient electrochemical ammonia catalysts and highlight which steps in the reaction pathway, such as nitrogen dissociation and hydrogen transfer, remain bottlenecks.

Doctoral students Constantine Athanitis and Filip Grajkowski, working with Professor Bilge Yildiz, applied machine learning to these computational results to screen alloy combinations that could overcome the identified limitations. The open-access findings were published August 11 in the journal EES Catalysis.

Independent expert Dane Morgan of the University of Wisconsin described the work as a foundation for designing new catalysts, noting that the clarified relationship between fundamental electronic properties and catalytic activity can accelerate computational screening. However, he cautioned that translating the calculations into practical catalysts will require many additional steps and real-world impact remains some distance away.

The researchers acknowledge the work is purely theoretical so far. Their next step is to build a working reaction cell to test the predicted catalyst materials under actual operating conditions. Athanitis said the team hopes to have pushed the boundary of candidate materials beyond what was previously considered, though even if practical application is not imminent, the direction of the research aligns with sustainability targets for ammonia production.