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The technique, which can store and release highly pure hydrogen with salts in the presence of amino acids, was developed by a team at the Leibniz Institute for Catalysis in Rostock, Germany.
The researchers, including Henrik Junge, Matthias Beller and colleagues, focused on hydrogen storage because of its potential as a widespread source of green energy. Handling large quantities of gaseous hydrogen is currently “cumbersome”, a research announcement said, and converting it to a liquid requires vessels that can withstand extremely high pressures.
The reversible storage of hydrogen in solid salts has emerged as a potential way to make the fuel easier to transport and handle, but the reactions to do this require precious metals as catalysts and may produce carbon dioxide as an unwanted by-product.
To tackle the issue, the team developed effective storage-release systems with both bicarbonate and carbonate salts, as well as manganese, which is a more widely available metal catalyst.
The researchers found that converting bicarbonate and hydrogen into formate, and vice versa, was most effective with potassium salts, a manganese-based catalyst, and lysine – an amino acid that acted as an additional promoter and reacted with carbon dioxide to capture it – at reaction temperatures below 93ºC.
After five storage-release cycles, the reaction system reportedly produced hydrogen with a high yield (80%) and purity (99%).
The team also showed that carbonate salts and glutamic acid can be part of the reusable storage-release system, with hydrogen yields up to 94%.
The technique paves the way for large-scale hydrogen storage in solids, the researchers said.
The work was published in ACS Central Science.
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