This document discusses nitrogen fixation, which is the process of converting atmospheric nitrogen gas into ammonia or other nitrogen compounds that can be used by plants and other organisms. It is difficult to fix nitrogen because nitrogen gas is very stable and its triple bonds are hard to break. The document outlines the Haber-Bosch process and Birkeland-Eyde process for industrial nitrogen fixation. Recent research aims to develop more efficient artificial and biological methods of nitrogen fixation, such as through transition metal complexes or engineering nitrogen fixation into food crops.

1. Topic: Why nitrogen is difficult to fix?
Research trends regarding Artificial
Nitrogen Fixation
Presented By: D.Sairam
Course : BSBT-102 ( Chemistry for Biologists)
Course Instructor: Dr. Vineet Sharma
Presentation Code: U5 P1

2. Contents
What is Nitrogen Fixation?
Why is Fixing Nitrogen an arduous
task?
Trends of Artificial Nitrogen Fixation
• Haber’s Process
• Birkeland- Hyde Process
 Recent Advancements

3. What is Nitrogen Fixation?
 Nitrogen fixation is a process in which nitrogen (N2) in the atmosphere is
converted into ammonium (NH4
+) or Ammonium related compounds.
 Atmospheric nitrogen or molecular nitrogen (N2) is relatively inert: it
does not easily react with other chemicals to form new compounds.
 . Performing this process manually is cumbersome and is a Herculean task
as it requires tremendous amount of Energy. It is here that enzymes come
to our rescue.
 The process holds enormous biological significance as nitrogen is
required to biosynthesize basic building blocks of plants, animals and
other life forms, e.g., nucleotides for DNA and RNA and amino
acids for proteins. It is also an essential component of various Fertilizers
and even Explosives.

4. Why is fixing Nitrogen ( N2) such an
arduous task?
 Nitrogen has to be fixed- to be converted from nitrogen
(N2) to be converted into another compound. So, to fix
nitrogen, its covalent bonds have to be broken .
 Covalent bonds are immensely strong and extremely
difficult to break, let alone the three that bond a (N2)
molecule.
 Another thing is that due to the fact that it is already being
stable and having a full valence shell, they no longer have
the desire to react with other elements, or form other
compounds.
 Hence, Fixing Nitrogen is an arduous task.

5. Haber’s Process
 This is a landmark process in Artificial Nitrogen Fixation.
 Here, Nitrogen ( retrieved from the atmosphere) combines with
Hydrogen ( obtained from Natural Gas) under the influence of Fe
(at 400-4500C and pressure of around 100-800 atm) with Mo acting
as a promoter.
 Playing a video for further explanation. ( url available in the end )

6. Birkeland-Eyde Process
• It is one of the first processes to take place while manufacturing nitrogen
based fertilizers. It was developed by Norwegian scientist Birkeland and
his partner Eyde.
• First an Electric Arc was formed between two coaxial electrodes, and
through the use of a strong magnetic field, was spread out into a thin disc.
The plasma temperature in the disc was in excess of 3000°C.
• Air was blown through this arc, causing some of the nitrogen to react with
oxygen forming nitric oxide. ( equation 1)
• By carefully controlling the energy of the arc and the velocity of the air
stream, yields of up to 4% nitric oxide were obtained.
• This process consumes a lot of Power, Energy and Resources so Birkeland
used to get power ( about 15 Mwh/Ton of nitric acid) from the
Hydroelectric Power Station.

7. • However, the same reaction is carried out by lightning,
providing a natural source for converting atmospheric
nitrogen to soluble nitrates.
• Equations
• N2 + 02 → 2 NO ( 1)
The hot nitric oxide is cooled and combines with atmospheric
oxygen to produce NO2
• 2 NO + O2 → 2 NO2
This nitrogen dioxide is then dissolved in water to give rise to
nitric acid, which is then purified by fractional distillation
3 NO2 + H20 → 2 HNO3 + NO

8. Recent Advancements in Artificial
Nitrogen Fixation
• Of late there has been extensive research in transition-metal complexes
capable of binding and activating N2. There has been research in this area to
ensure easy conversion of N2 to NH3
• Approaches in Synthetic Biology has suggested that one day crops will be
able to absorb N2 on their. Recently ( 2013) a team of 4 researchers each
from UK and US have started using Synthetic Biology as a tool for
designing crops that do not require Fertilizer.
• In some places we have seen Molybdenum and Phosphine complexes
being used as a medium for carrying out Artificial Nitrogen Fixation.
• Another possibility is engineering of the legume symbiosis into cereals

9. References
 http://www.ac.uni-kiel.de/tuczek/research-new/synthetic-nitrogen-fixation
 http://kids.britannica.com/comptons/article-205610/nitrogen
 http://en.wikipedia.org/wiki/Nitrogen_fixation
 http://www.infoplease.com/encyclopedia/science/nitrogen-cycle-effects-artificial-
fixation.html
 https://www.youtube.com/watch?v=kpxogOhFTPo
 http://www.solarharvestfarm.com/haberboschnitrogenvsbiological1.html
 http://www.treehugger.com/sustainable-agriculture/food-crops-could-be-made-
self-fertilizing-nitrogen-fixing-bacteria-making-artificial-fertilizer-unecessary.
html
 http://www.nsf.gov/news/news_summ.jsp?cntn_id=128878
 http://jxb.oxfordjournals.org/content/65/8/1939
 http://pubs.rsc.org/en/content/articlelanding/2012/ic/c2ic90033e#!divAbst
ract
 http://pubs.acs.org/doi/abs/10.1021/cr60316a001

10. THANK YOU