Reducing nitrogen with boron and beer

Boron can be used to convert nitrogen into ammonium. Sincerely: Team Bronchieve

Mankind is dependent on ammonium in synthetic fertilizers for food. However, the production of ammonia from nitrogen is extremely energy-intensive and requires the use of transition metals.

Researchers at the Julius-Maximillions-Universiteit (JMU) Würzburg in Bavaria, Germany, have now achieved lower pressures at room temperature without the conversion of nitrogen and the need for transition metals. This was reported in the journal by a research group led by JMU scientist Holzer Brunshivig Nature chemistry.

A new nitrogen binding toolbox

Industrial production of ammonia, the so-called Haber-Bosch process, requires high temperatures and pressures, and is estimated to consume about two percent of all energy produced on Earth. This process also relies on transition metal elements, relatively heavy and reactive atoms.

In 2018, Professor Bronschiev’s team reported bonding and chemical conversion of nitrogen using only one molecule formed of light, non-metallic atoms. A year later, he used a similar system in the laboratory to demonstrate the first combination of two nitrogen molecules, a reaction that would otherwise have been seen only in Earth’s upper atmosphere and plasma conditions.

The key to both of these discoveries was the use of boron, the fifth lightest element, as an atom that reminds nitrogen. “After these two discoveries, it was clear that we had a very specialized system on our hands,” Bronschwig says.

just add water

Although their system binds and converts nitrogen, only half of the puzzle was in place. “We knew that completing the conversion of nitrogen into ammonia would be a major challenge, as it required a complex sequence of chemical reactions that are often incompatible with each other,” explains the professor at JMU.

The simplest of the reagents resulted in success: the water marks left behind in a sample were sufficient to promote a sequential reaction that brought the team only one step away from the target ammonium. It was later discovered that the main reactions could be carried out using a solid acid, allowing the reactions to occur sequentially in a single reaction flask at room temperature.

Making Ammonium with Beer

Realizing that the acidification of the process also appeared to work with simple reagents such as water, the team repeated the reaction using locally brewed Würzberger Hofbrü Beer. To their delight, they were able to detect the pre-ammonium product in the reaction mixture.

“This experiment was somewhat fun, but it also shows how tolerant the system is to water and other compounds,” Dr. Mark-André Legar, postdoctoral researcher who initiates the study, explains. Dr. Ryan DeVurst says, “Nitrogen deficiency is one of the most important chemical reactions for mankind. This is undoubtedly the first time, and is particularly fitting, that it was done in Germany.” Akademicher Obert and co-author of the study.

A lot of work to do

The reaction, while exciting, is still far from being a truly practical process for industrially produced ammonium. Ideally, a way would be to find a way to recreate the active species to make the process energy efficient and economical.

Nevertheless, the discovery is an exciting demonstration that even the lightest elements can tackle the biggest challenges in chemistry. “There is a lot to be done here,” says Holger Bronschwig, but boron and other lighter elements have surprised us many times already.

Newly designed molecules bind nitrogen

more information:
A pot for ammonium chloride in a core group element, room temperature conversion Nature chemistry (2020). DOI: 10.1038 / s41557-020-0520-6,

Provided by University of Würzburg

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