Safe, easy and affordable hydrogen mining for a decarbonized future

Artistic concept of energy that catalyzes chemical reactions

Scientists at the RIKEN Center for Emerging Matter Sciences in Japan have found a way to safely and efficiently store ammonia by chemical reaction. They used a perovskite called ethylammonium lead iodide (EAPbI3) which interacts with ammonia at room temperature, modifying its structure and storing the ammonia inside. Notably, the stored ammonia can be removed simply by gently heating the compound, and the perovskite can be reused for continuous cycles of storage and extraction.

Japanese scientists have discovered an ethylammonium lead iodide compound that can safely and effectively store and release ammonia. This finding has potential for the role of ammonia as a carbon-free hydrogen carrier, contributing to the transition to a decarbonizing society.

Researchers at the RIKEN Center for Emerging Materials Science (CEMS) in Japan have discovered a compound that uses a chemical reaction to store ammonia, potentially providing a safer and easier way easier to store this important chemical. This finding, published in the journal Journal of the American Chemical Society on July 10, not only can ammonia be safely and conveniently stored, but also vital hydrogen is transported. This discovery will help pave the way for a decarbonizing society with a realistic hydrogen economy.

For society to transition from carbon-based energy to hydrogen-based energy, we need a safe way to store and transport hydrogen, which itself is highly flammable. One way to do this is to store it as part of another molecule and extract it as needed. Ammonia, chemical name is SMALL3makes a good hydrogen carrier because three hydrogen atoms are packed in each molecule, with almost 20% of ammonia being hydrogen by weight.

Ammonia storage and extraction by chemical reaction

Reversible changes in color and crystal structure during ammonia storage and extraction through chemical conversion. Credit: RIKEN

However, the problem is that ammonia is a highly corrosive gas that is difficult to store and use. Currently, ammonia is typically stored by liquefying it at temperatures much lower than freezing in pressurized containers. Porous compounds can also store ammonia at room temperature and pressure, but the storage capacity is low and it is not always possible to recover ammonia easily. New research reports the discovery of perovskite, a material with a distinctive repetitive crystalline structure that can easily store ammonia and also allows for easy and complete recovery at relatively low temperatures. .

The team led by Masuki Kawamoto at RIKEN CEMS focused on ethylammonium perovskite lead iodide (EAPbI).3), chemically written as ONLY3ONLY2SMALL3PbI3. They found that its one-dimensional columnar structure undergoes chemical reaction with ammonia at room temperature and pressure, and converts flexibly into a two-dimensional layered structure called lead iodide hydroxide, or Pb. (OH)I. The result of this process is that ammonia is stored in a layered structure through chemical conversion. Therefore, EAPbI3 can safely store corrosive ammonia gas as nitrogen compounds in a much cheaper process than liquefaction at -33°C (-27.4°F) in pressurized vessels. More importantly, the process of recovering stored ammonia is just as simple.

“Surprisingly, the ammonia stored in ethylammonium lead iodide could be easily extracted by gently heating it,” Kawamoto said. The stored nitrogen compound undergoes a reverse reaction at 50°C (122°F) under vacuum and returns to ammonia. This is much lower than the 150°C (302°F) and above required to extract ammonia from porous compounds, yielding EAPbI.3 an excellent means of treating corrosive gases in a simple and cost-effective process. In addition, after reverting to the one-way column structure, the perovskite can be reused, allowing the ammonia to be stored and extracted multiple times. An added bonus is that the normally yellow compound becomes 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 stored ammonia.”

The new storage method has several uses. In the short term, the researchers have developed a safe method for storing ammonia, which already has a wide range of applications in society, from fertilizers to pharmaceuticals to textiles. «In the long-term, we hope that this simple and effective approach can be part of the solution to achieving a decarbonized society through the use of decarbonisation,» said co-author Yoshihiro Ito of RIKEN CEMS. ammonia makes hydrogen carbon-free. transport.»

This research will help achieve the 2016 Sustainable Development Goals (SDGs) set forth by the United Nations, especially Goal 7: Clean and Affordable Energy and Goal 13: Climate Action .

Reference: «Ammonia chemical storage through dynamic structural transformation of hybrid perovskite compounds» July 10, 2023, Journal of the American Chemical Society.
DOI: 10.1021/jacs.3c04181

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