United States. Researchers at the University of Notre Dame are developing a renewable energy approach to synthesizing ammonia. The Haber-Bosch process developed in the early twentieth century to produce ammonia is based on non-renewable fossil fuels and has limited applications only for large centralized chemical plants.
The new process, published in Nature Catalysis, uses a plasma, an ionized gas, in combination with non-noble metal catalysts to generate ammonia under much milder conditions than is possible with Haber-Bosch. The energy in the plasma excites nitrogen molecules, one of the two components involved in ammonia production, allowing them to react more quickly with catalysts.
Because the energy for the reaction comes from plasma rather than high heat and intense pressure, the process can be carried out on a small scale. This makes the new process suitable for use with intermittent renewable energy sources and for the production of distributed ammonia.
"Plasmas have been considered by many to be a way to produce ammonia that does not rely on fossil fuels and had the potential to be applied in a less centralized way," said William Schneider, H. Clifford and Evelyn A. Brosey Professor of Engineering, an affiliate member of ND Energy and co-author of the study. "The real challenge has been finding the right combination of plasma and catalyst. By combining molecular models with results in the lab, we were able to focus on combinations that had never been considered before."
The research team led by Schneider; David Go, Rooney Family Associate Professor of Engineering in Aerospace and Mechanical Engineering; and Jason Hicks, an associate professor of chemical and biomolecular engineering, found that because nitrogen molecules are activated by plasma, the requirements for metal catalysts are less stringent, allowing less expensive materials to be used throughout the process. This approach overcomes the fundamental limits of the heat-driven Haber-Bosch process, allowing the reaction to take place at Haber-Bosch rates under much milder conditions.
"The goal of our work was to develop an alternative approach to ammonia manufacturing, but the insights that emerged from this collaboration between our research groups can be applied to other difficult chemical processes, such as converting carbon dioxide into a less harmful and more useful product. As we continue to study plasma-ammonia synthesis, we will also consider how plasma and catalysts could benefit other chemical transformations," Hicks said.
Data Source Provider: University of Notre Dame.
