Tuesday, June 18, 2024

New method stores and releases highly pure hydrogen with salts

In contrast to the traditional fossil-based linear economy, the circular economy is a model of production and consumption, which involves reducing, reusing, and recycling, aiming to tackle the global resource shortage.

Now, researchers from Leibniz Institute for Catalysis have developed a method to store and release highly pure hydrogen with salts in the presence of amino acids.

Hydrogen gas could someday replace fossil fuels as a clean energy source, producing only water and energy. However, hydrogen is a highly flammable gas, and handling large quantities of it is quite cumbersome. Also, converting it to a liquid requires vessels that can withstand extremely high pressures.

The reversible hydrogen storage in solid salts has emerged as one potential way to make the fuel easier to transport and handle. The salt can be reused again to store more hydrogen, making it a cyclic process. But the reactions to do this require precious metals as catalysts and may produce carbon dioxide as an unwanted byproduct.

So, researchers have developed effective storage-release systems with both bicarbonate and carbonate salts, as well as manganese, which is a more widely available metal catalyst. Researchers found that converting bicarbonate and hydrogen into the format, 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 200 Fahrenheit (93 °C). After five storage-release cycles, the reaction system produced hydrogen with a high yield (80%) and purity (99%).

The team also showed that carbonate salts and glutamic acid could be part of the reusable storage-release system with hydrogen yields up to 94%. Researchers say that this technique paves the way for large-scale hydrogen storage in solids.

Journal reference:

  1. Duo Wei, Xinzhe Shi, Peter Sponholz, Henrik Junge, and Matthias Beller. Manganese promoted (Bi)carbonate hydrogenation and formate dehydrogenation: Toward a circular carbon and hydrogen economy. ACS Central Science 2022. DOI: 10.1021/acscentsci.2c00723