New catalyst accelerates release of hydrogen from ammonia

Cooperation project involving Kiel University aims at facilitating import of sustainably produced energy.

Germany can probably only meet its demand for climate-friendly hydrogen by imports, for example from South America or Australia. For such long-distance transport, hydrogen can be converted into ammonia, for example. To facilitate the release of the hydrogen afterwards, researchers from the Institute of Inorganic Chemistry at Kiel University (CAU) and their cooperation partners have developed a more active and cost-effective catalyst. The results were obtained as part of the hydrogen flagship project TransHyDE funded by the German Federal Ministry of Education and Research (BMBF) and have recently been published in the renowned journal Nature Communications.

The ability to store energy from wind or solar power plays a key role in the energy transition. “Storing energy in the form of chemical compounds such as hydrogen has many advantages. The energy density is high and the chemical industry also needs hydrogen for many processes,” says Malte Behrens, Professor of Inorganic Chemistry at Kiel University. In addition, “green hydrogen” can be produced by electrolysis using electricity from renewable energy sources without producing CO2.

Infrastructure for ammonia already exists

But transporting hydrogen directly from regions where wind and solar power are cheap is not easy. An interesting alternative is the chemical conversion into ammonia. Ammonia itself contains a relatively high amount of hydrogen, and a well-developed infrastructure for its oversea transport already exists. “Ammonia can be liquefied easily for transport, is already produced on a megaton scale and shipped and traded worldwide,” says Dr. Shilong Chen, the leader of the Kiel subproject in the TransHyDE project “AmmoRef”. The two scientists from CAU’s priority research area KiNSIS (Kiel Nano, Surface and Interface Science) are collaborating with colleagues from Berlin, Essen, Karlsruhe and Mülheim/Ruhr. Together they are investigating how hydrogen can be catalytically released from ammonia after transport. Their newly developed catalyst significantly accelerates this reaction.

AmmoRef is one of ten TransHyDE projects funded by the BMBF. Scientists from a total of eight institutions are working on various sub-projects to improve hydrogen transport technologies. The results will be incorporated into the recommendations for the national hydrogen infrastructure.

Metal combination makes catalyst highly active

“A catalyst accelerates a chemical reaction and is therefore directly responsible for the efficiency of chemical processes and energy conversion,” Behrens explains. The faster the ammonia reforming process takes place, the lower are the conversion losses caused by the chemical storage of hydrogen in ammonia. “Our catalyst has two special features,” says Chen. “First, it is made of the relatively inexpensive base metals iron and cobalt. Secondly, we have developed a special synthesis process that allows a very high metal loading of this catalyst.” Up to 74% of the material consists of active metal nanoparticles, which are arranged between support particles in a way that cavities on the nano-scale are formed looking like a porous metallic nano-sponge. “The combination of the two metals in an alloy is also crucial,” Behrens explains. On their own, both metals are less catalytically active. The combination creates highly active bimetallic surfaces with properties that are otherwise only known from much more expensive precious metals.

“We will continue to investigate this catalyst in the AmmoRef consortium, in which industrial companies are also involved, and transfer it from basic research to application,” says Behrens, announcing the next steps. To this end, the team in Kiel will now work on scaling up the synthesis.

The editors of Nature Communications highlighted the article as “particularly interesting”. In addition to Kiel University (CAU), the Karlsruhe Institute of Technology (KIT), the Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr (MPI CEC), the University of Duisburg-Essen (UDE) and the Fritz Haber Institute of the Max Planck Society (FHI), Berlin, were involved in the results presented there.

The hydrogen flagship projects are an important contribution by the Federal Ministry of Education and Research (BMBF) to the implementation of the National Hydrogen Strategy. This was adopted by the German government in 2020 and updated in 2023 to prepare Germany’s entry into the hydrogen economy.

About the joint project „AmmoRef”:
Long title: Verbundvorhaben TransHyDE_FP3: Reformierung von Ammoniak – Transport von H2 über Derivate
Total funding amount: approx. 12,5 Mio. €
Duration of the project: 04/2021–03/2025
Partner: BASF, Kiel University (CAU), CLARIANT, Dr Ryll Labs, Fraunhofer Institute for Solar Energy Systems ISE, Max Planck Institute for Chemical Energy Conversion (MPI CEC, coordination), Technische Universität Berlin (TU Berlin), thyssenkrupp

Wissenschaftliche Ansprechpartner:

Prof. Dr. Malte Behrens
Institute of Inorganic Chemistry, CAU
Phone: + 49 431 880-2410
mbehrens@ac.uni-kiel.de

Originalpublikation:

Shilong Chen, Jelena Jelic, Denise Rein, Sharif Najafishirtari, Franz-Philipp Schmidt, Frank Girgsdies, Liqun Kang, Aleksandra Wandzilak, Anna Rabe, Dmitry E. Doronkin, Jihao Wang, Klaus Friedel Ortega, Serena DeBeer, Jan-Dierk Grunwaldt, Robert Schlögl, Thomas Lunkenbein, Felix Studt & Malte Behrens. Highly loaded bimetallic iron-cobalt catalysts for hydrogen release from ammonia. Nat Commun 15, 871 (2024). https://doi.org/10.1038/s41467-023-44661-6

Weitere Informationen:

http://www.wasserstoff-leitprojekte.de/projects/transhyde More information on the flagship project TransHyDE
https://www.uni-kiel.de/en/research/priority-research-areas/details/news/26-wass… link to the press release
http://www.kinsis.uni-kiel.de/en Priority Research Area of Kiel University