Morgan

1. To: Dr. Douglas Price
From: Ahmad Shehab
Date: 2/2/2020
Ammonia Synthesis Process
Introduction
Ammonia is one of the lagers production chemical around the world used in fertilizer. In
order to produce ammonia different process strategies invented and updated until this day. In
early 1900’s the first process developed called Haber-Bosch process used in for long time and
got upgraded through decade. However, now days because of emit vast amounts of carbon
dioxide (CO2) and the low efficiency to produce ammonia, new technology came the reduce this
problem by using electrochemical cell. Although, in this report we will show how the technology
work, condition such as (temperature, pressure, catalysts, etc.), engineering analysis (technical
and economic), required utilities, and flow rate.
Our objective is to find the most suitable technology to use in ammonia production that
achieve 50 metric tons per day with purity at least 99.5%.
Harber-Bosch process
Process developed by Fritz Haber and Carl Bosch to produce ammonia. In this process reacts
highly purified hydrogen and nitrogen 3:1 molar ratio( figure1).
Figure 1
The catalyst used is Iron-Based or Potassium hydroxide affected by the presence of any
oxygenated compound, so the feed gas should clean CO, CO2 and H2O,O2 from the air. This
reaction is highly sensitive to temperature and pressure, runs at high pressure, 60 to 180 bar, to
reach the proper conversion. Also, the reaction only achieve single-pass of less than 20%, so
high recycle rate is necessary. In Harber-Bosch process the separation between ammonia product
and unreacted feed gases is not difficult but energy intensive, can be accomplished using a single
stage phase separator (“Flash”) after condensing the ammonia product using a chiller.

2. Figure 2
Figure 2 shows the process where nitrogen and hydrogen goes into iron catalyst at 200 atm
pressure and temperature of 400-450 Celsius. Then to a separation column separate ammonia
products as a liquid after cooling down the temperature and hydrogen and nitrogen in gas phase
goes to the recycle stream.
Even though each pass of hydrogen and nitrogen conversion making less that 20%, the over
conversion is 98%. However, one of the problems in this process is no reaction occur on the
surface of the catalyst, so we need to shift the equilibrium position to the right as far as possible
in order to produce maximum amount of ammonia. In addition, we need to lower the temperature
as possible to increase the efficiency but because of the high temperature in the process 400-450
Celsius, the goal is to reach equilibrium within very short time that will in contact with the
catalyst.
Separating the ammonia
The temperature of the liquid is lowered enough to turn the ammonia to a liquid the nitrogen and
hydrogen remain gases and can be recycled.
Economics
- High pressure needs extremely strong pipes and vessels to withstand that increase Capital Cost
when plant is build.
- Running cost is high because of the pressure.
- Adding catalyst only speed up the reaction, no effect on position of the equilibrium (almost no
reaction without catalyst).
- 10 MW per metric ton best of 7.8 MW.
Electrochemical Cell

3. Figure 3
Electrochemical cell one of the modern synthesis to produce ammonia. Simply we have the
electrolyze and the water inter the anode side where hydrogen is separated from oxygen. Then
hydrogen moves to the cathode through membrane where nitrogen flow from the other side to
contact with the hydrogen on the cathode to make ammonia by using renewable energy to power
the system. Oxygen goes out as undesired product. Figure 4 shows the reaction.
Figure 4
This technology moderate temperature at 150–350 °C and low <100 °C. also, low pressure.
Advantages
1- Low temperature, low pressure.
2- 50% less CO2 emissions.
3- High efficiency.
4- Purity of 99.999%
5- 7 MW per metric ton.
Disadvantages
1- Slow process.
2- low catalytic activity of the cathodic electrode (and consequently, reduced Faradaic
Efficiency)
3- low protonic conductivity of the cell.
Since this technology is new we need to consider these:

4. A- selection of materials and construction of the cathodic electrode.
B- design and fabrication of the electrolyte-electrode interphase.
C- selection of the operating conditions
Conclusion
Electrochemical Cell is great option to produce ammonia however this technology need for
intensive collaboration among scientists and engineers working in different fields (solid state
Ionics, catalysis, electrochemistry, reactor design) in order to bring this process into industrial
practice. On the other hand, Haber-Bosch process is better process for our plant design. In
addition, there are a lot of alternatives to improve the process and we can apply the process in
industry.
Works Cited
Clark, J. (2013, April). Haber Process. Retrieved from THE HABER PROCESS:
https://www.chemguide.co.uk/physical/equilibria/haber.html
Department of Chemical Engineering, A. U. (2019, Aug 30). Electrochemical Synthesis of
Ammonia: Recent Efforts and Future Outlook. Retrieved from NCBI:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6780605/
RICHARDSON, J. (2016, Sep). Introduction to Ammonia Production. Retrieved from AICHE:
https://www.aiche.org/resources/publications/cep/2016/september/introduction-ammonia-
production
Service, R. F. (2018, Jul 12). Ammonia—a renewable fuel made from sun, air, and water—could
power the globe without carbon. Retrieved from Science:
https://www.sciencemag.org/news/2018/07/ammonia-renewable-fuel-made-sun-air-and-
water-could-power-globe-without-carbon