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Methods to increase ammonia production

5/3/2019

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The book Chemistry on a Budget contains inexpensive chemistry labs that are useful with easy to obtain materials.
 
There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report.  This way the teacher has the option!  Each lab is two pages to allow for one two-sided handout. 
 
A 5-Star Customer Review of Chemistry on a Budget at amazon.com states:

“[S]traight forward, to the point, using household chemicals… this is the lab book for you. 
I teach high school chemistry and this is exactly what I was looking for. Labs included simple household chemicals that could be easily found. Nice format, easy to follow along procedures, and touches on every topic of our chemistry curriculum.”
 
You can buy this lab book for $23 at amazon.com or lulu.com. It will take 1-2 weeks to get to you -- Order Now.  It’s a great resource!
 
http://www.amazon.com/Chemistry-Budget-Marjorie-R-Heesemann/dp/0578129159/ref=sr_1_1?s=books&ie=UTF8&qid=1389410170&sr=1-1&keywords=chemistry+on+a+budget

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html
 
*Some of you have already purchased my lab book – be sure to check out Page 141 !

“Global food production requires ammonia-based fertilizers. The industrial transformation of atmospheric nitrogen gas (N2, also known as dinitrogen) into ammonia (NH3) is therefore essential for human life. Despite the simplicity of the molecules involved, the cleavage of the strong nitrogen–nitrogen triple bond (the N≡N bond) in dinitrogen and the concomitant formation of nitrogen–hydrogen (N–H) bonds poses a difficult challenge for catalytic chemistry, and typically involves conditions that are costly in terms of energy requirements: high reaction temperatures, high pressures or combinations of reactive reagents that are difficult to handle and energy-intensive to make. …

Motivated by a looming global fertilizer shortage at the turn of the twentieth century, and later by munitions shortages (ammonia can be used to make explosives), the chemists Fritz Haber and Carl Bosch were the first to demonstrate that dinitrogen could be ‘pulled from air’ and converted to ammonia. In the modern’version of the Haber–Bosch process, dinitrogen and hydrogen gas are combined over a catalyst typically based on iron to produce ammonia. Today, global ammonia production occurs at a rate of about 250–300 tonnes per minute, and provides fertilizers that support nearly 60% of the planet’s population. …

Writing in Nature, Ashida et al. demonstrate that a samarium compound mixed with water and combined with a molybdenum catalyst can promote ammonia synthesis from dinitrogen under ambient conditions. The work opens up avenues of research in the hunt for ammonia-making processes that operate under ambient conditions, and raises the question of what an ideal process should be. …

The modern conditions for ammonia synthesis involve temperatures greater than 400 °C and pressures of approximately 400 atmospheres, and are therefore often said to be ‘harsh’. This common misconception has motivated chemists to find ‘milder’ alternatives that use new catalysts to lower the operating temperatures and pressures. In reality, the search for new catalysts should be inspired by the need to reduce the capital expenditure associated with building ammonia plants, and by the requirement to reduce carbon emissions — not only from ammonia synthesis itself, but also from production of the hydrogen used in the process. “
https://www.nature.com/articles/d41586-019-01213-7
 
Another method to produce ammonia has been developed at the University of Tokyo (UTokyo).  “Ammonia -- a colorless gas essential for things like fertilizer -- can be made by a new process which is far cleaner, easier and cheaper than the current leading method. UTokyo researchers use readily available lab equipment, recyclable chemicals and a minimum of energy to produce ammonia. Their Samarium-Water Ammonia Production (SWAP) process promises to scale down ammonia production and improve access to ammonia fertilizer to farmers everywhere. …

The Haber-Bosch process only converts 10 percent of its source material per cycle so needs to run multiple times to use it all up. One of these source materials is hydrogen (H2) produced using fossil fuels. This is chemically combined with nitrogen (N2) at temperatures of about 400-600 degrees Celsius and pressures of about 100-200 atmospheres, also at great energy cost. …

 ‘Worldwide, the Haber-Bosch process consumes 3 to 5 percent of all natural gas produced, around 1 or 2 percent of the world's entire energy supply,’ explained Nishibayashi. ‘In contrast, leguminous plants have symbiotic nitrogen-fixing bacteria that produce ammonia at atmospheric temperatures and pressures. We isolated this mechanism and reverse engineered its functional component -- nitrogenase.’

Over many years, Nishibayashi and his team used lab-made catalysts to try and reproduce the way nitrogenase behaves. Others have tried but their catalysts only produce dozens to several hundred ammonia molecules before they expire. Nishibayashi's special molybdenum-based catalyst produces 4,350 ammonia molecules in about four hours before it expires.

‘Our SWAP process creates ammonia at 300-500 times the rate of the Haber-Bosch process and at 90 percent efficiency,’ continued Nishibayashi. ‘Factor in the gargantuan energy savings in the process and sourcing of raw materials and the benefits really show.’

Anyone with the proper source materials can perform SWAP on a table-top chemistry lab, whereas the Haber-Bosch process requires large-scale industrial equipment. This could afford access to those who lack the capital to invest in such large, expensive equipment. The raw materials themselves are a huge saving in terms of cost. …

SWAP takes in nitrogen (N2) from the air -- as the Haber-Bosch process does -- but the special molybdenum-based catalyst combines this with protons (H+) from water and electrons (e-) from samarium (SmI2). Samarium -- also known as Kagan's reagent -- is currently mined and is used up in the SWAP process. However samarium can be recycled with electricity to replenish its lost electrons and researchers aim to use cheap renewable sources for this in the future.
https://www.sciencedaily.com/releases/2019/04/190424153632.htm
 
It is interesting that two methods have recently been developed to improve the efficiency of a chemical process that was discovered in 1913.

Remember to remind your students to look for replication of these methods .
 

You may want to use either or both of these articles as a Homework assignment to show these current developments.
 
*This Blog contains several entries that would be helpful to your chemistry classroom.  Check out the Topic List to help you to find past Blog entries.
 
Also, Write To Me about your successes, challenges, or questions in the Chemistry Classroom.
 
Remember, buying a copy of the lab book Chemistry on a Budget can be very useful to your Chemistry classroom with labs and class article ideas.

Have a great weekend!

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    Marjorie R. Heesemann is a chemistry teacher with 15 years of experience who is now working to develop resources for the Chemistry classroom.

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