2023-07-11 10:33:18
Hydrogen Storage – RAIMOND SPEKKING/NORTHEASTERN UNIVERSITY
MADRID, 11 Jul. (EUROPA PRESS) –
A new compound that uses a chemical reaction to store ammonia more easily and safely, It also offers the possibility of doing so with the important hydrogen that is transported.
This finding from researchers at the RIKEN Center for the Science of Emerging Matter (CEMS) in Japan “should help lead the way towards a decarbonized society with a practical hydrogen economy,” they say in an article published in the Journal of the American Chemical Society.
For society to make the switch from carbon-based to hydrogen-based energy, we need a safe way to store and transport hydrogen, which itself is highly combustible. One way to do this is to store it as part of another molecule and extract it as needed. Ammonia, chemically written as NH3, is a good carrier of hydrogen. because each molecule contains three hydrogen atoms, and almost 20% of ammonia is hydrogen by weight.
The problem, however, is that ammonia is a highly corrosive gas, making it difficult to store and use. At the moment, ammonia is usually stored by liquefying it at temperatures well below freezing in pressure resistant containers. Porous composites can also store ammonia at room temperature and pressure, but storage capacity is low and ammonia cannot always be easily recovered.
The new study reports the discovery of a perovskite, a material with a distinctive repeating crystalline structure, which can easily store ammonia and also allows easy and complete recovery at relatively low temperatures.
The research team led by Masuki Kawamoto at RIKEN CEMS focused on perovskite ethylammonium lead iodide (EAPbI3), chemically written as CH3CH2NH3PbI3. They found that its one-dimensional columnar structure undergoes a chemical reaction with ammonia at room temperature and pressure, dynamically transforming into a two-dimensional layered structure called lead iodide hydroxide, or Pb(OH)I.
As a result of this process, ammonia is stored within the layered structure through chemical conversion. Therefore, EAPbI3 can safely store the corrosive ammonia gas as a nitrogen compound. in a process that is much more economical than liquefaction at -33 °C in pressurized containers. Even more important, the process to recover stored ammonia is just as simple.
“To our surprise, the ammonia stored in lead ethylammonium iodide could be easily extracted by gently heating it,” says Kawamoto. The stored nitrogen compound undergoes a reverse reaction at 50°C under vacuum and turns back into ammonia.. This temperature is much lower than the 150°C or higher required to extract ammonia from porous compounds, making EAPbI3 an excellent means of handling corrosive gases in a simple and cost-effective process.
In addition, after reverting to the one-dimensional columnar structure, the perovskite can be reused, allowing ammonia to be repeatedly stored and mined. An additional advantage was that the normally yellow compound turned white after the reaction. According to Kawamoto, “the ability of the compound to change color when ammonia is stored means that color-based ammonia sensors can be developed to determine the amount of ammonia stored.”
The new storage method has several uses. In the short term, the researchers have developed a safe method for storing ammonia, which already has multiple uses in society, from fertilizers to pharmaceuticals to textiles. “In the long term,” says co-author Yoshihiro Ito of RIKEN CEMS, “we hope that this simple and efficient method can be part of the solution to achieve a decarbonized society.” by using ammonia as a carbon-free hydrogen carrier”.
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