How to Produce Green H2 from Ammonia?

Ammonia has traditionally been used as fertilizer, but over the last few years, it has slowly entered the realm of energy and the future seems to be great for it. It is now used as a way of storing and transporting hydrogen as well. Even as the world seeks alternatives to fossil fuels, ammonia is part of the options that are considered to be useful as we go into the future of renewable and clean energy sources. 

What Makes Ammonia a Good Source of Hydrogen? 

Ammonia (NH3) is a compound of nitrogen and hydrogen. Its properties make it an appropriate source of hydrogen hence the interest in it as a source of energy. More specifically, ammonia can easily supply hydrogen that can be used to meet the energy needs of various types of applications. This is possible due to the properties of ammonia that give it attractiveness as well as the appropriateness as a possible source of hydrogen. 

One property that makes ammonia a good supplier or source of hydrogen is its behaviour when subjected to pressure. It easily liquefies at a temperature of -33°C. This is much favourable compared to that of hydrogen which is -253°C. Ammonia is, therefore, a good way to store hydrogen which can later be extracted for use in providing energy for applications that are the most appropriate for it. 

It is also much easier to move or transport ammonia compared to pure hydrogen. It requires less extreme pressures and temperatures that would otherwise not be appropriate for hydrogen. In addition, it is worth noting that ammonia has even 50% more energy than a similar amount of space that is filled with hydrogen. For this and other great properties or characteristics of ammonia, there is no doubt that it makes a good source of green H2. 

Hydrogen Production from Ammonia 

Hydrogen can be produced from ammonia through various processes. The hydrogen extracted from ammonia is often used in fuel cells that are used in various applications. Different methods can be used, but it all depends on what is intended to be achieved at the end of the process. In most cases, the commonly used methods to produce hydrogen from ammonia are:

  • Catalytic Decomposition of Ammonia 

This method makes use of high temperatures to decompose ammonia into hydrogen and other elements. That is, at high temperatures, ammonia begins to decompose into hydrogen. More specifically, at as high temperatures as 425°C, about 98-99% of ammonia decomposes, but the rate of decomposition can be faster or slower depending on the temperature as well as the catalysts that are used in the process. 

Catalytic decomposition of ammonia is the most often used method of extracting hydrogen from ammonia. Experts argue that it is the best when it comes to the large scale production of hydrogen from ammonia. At early stages, this process focused much on the use of iron-based catalysts, but over time, various alloys, metals and compounds that exhibit better features have also been developed for use in the catalytic decomposition of ammonia. 

  • Electrolysis of Ammonia 

This process is also known as electro-oxidation. The process involves the coupling of ammonia specifically in an alkaline medium so that water is reduced at the cathode and the oxidation of ammonia at the anode to produce hydrogen. It is effective in extraction and there are reports that it’s the best when it comes to scalability and versatility. Due to these features or properties of the process, electrolysis is recommended for use where there are variations in energy sources. 

So far, numerous works have been done to develop the best catalysts that can be used in the electrolysis of ammonia to produce hydrogen. More research is also ongoing on how to reduce the energy required for this process. The success of such projects is what might eventually make hydrogen the best source of clean and renewable energy going forward. 

A few other methods are also being tested for use in generating hydrogen from ammonia. For instance, some works have been done on urea electrolysis as an alternative method. However, going by the results, the two methods we’ve discussed (catalytic decomposition and electrolysis of ammonia) remain the best ways to produce green H2 from ammonia.