Study of iron catalysts provides insight into ammonia decomposition
The use of ammonia is considered a promising method to transport hydrogen. But we also need an efficient process to convert it back into hydrogen and nitrogen.
An international research team has gained new insights into the mode of operation of iron catalysts that can be used to split ammonia into nitrogen and hydrogen. Hydrogen is converted to ammonia to facilitate the transport of energy carriers. This means that we also need a catalyst that can split the ammonia back into its starting materials.
A team from Germany’s Ruhr University Bochum, the Max Planck Institute for Chemical Energy Conversion (MPI CEC) in Mülheim an der Ruhr, the Technical University of Berlin, and the Italian Institute of Technology in Genoa has now investigated how iron catalysts drive this reaction. We explain in detail how this is possible. Article published in ACS Catalysis.
How to make hydrogen transportable
Green hydrogen is attracting attention as a promising energy carrier. It can be produced by splitting water using wind or solar energy. However, in many cases the locations where hydrogen is needed do not have suitable conditions for water electrolysis.
To transport hydrogen, it must be liquefied, which is only possible at extremely low temperatures. Therefore, converting hydrogen to ammonia is considered an attractive alternative as it can be liquefied at much higher temperatures.
“Furthermore, the chemical industry already has an established infrastructure for ammonia processing,” says Professor Martin Müller, Director of the Bochum Institute for Industrial Chemistry and Max Planck Fellow at MPI CEC.
An efficient catalyst is required to break down ammonia (NH3) back to its starting compounds nitrogen (N2) and hydrogen (H2). The problem is that conventional iron catalysts generally promote undesirable reactions to produce iron nitride instead of nitrogen.
In the new study, the researchers showed exactly how this side reaction occurs. They tested ammonia decomposition using the latest generation catalyst provided by Clariant.
A team consisting of Dr. Maximilian Purcell, Professor Astrid Müller and Professor Martin Müller from Ruhr-University Bochum and MPI CEC carried out related experiments. The results of this study were refined using complex molecular dynamics simulations with machine learning conducted by partner institutions in Italy. A team from the Technical University of Berlin was able to use X-ray diffraction to identify the iron nitride that forms under reaction conditions and track its evolution.
“Our findings could be used in the future to develop more efficient catalysts for the decomposition of ammonia,” concludes Martin Muhler. “Ammonia synthesis and decomposition has a long track record,” he added. “We cite scientific publications from the past 100 years.” These include the work of Gerhard Ertl, Martin Müller’s doctoral supervisor, who won the Nobel Prize for his research in 2007.
Further information: M. Purcel et al, Formation and decomposition of iron nitride during ammonia decomposition over Wustite-based bulk iron catalysts, ACS Catalysis (2024). DOI: 10.1021/acscatal.4c04415
Provided by Ruhr University Bochum
Citation: Iron catalyst research provides insights into ammonia decomposition (October 8, 2024) from https://phys.org/news/2024-10-iron-catalyst-insights-ammonia-decomposition.html 2024 Retrieved October 8, 2018
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