AMMONIA

Prepared By: 13BCH022

13BCH025

13BCH036

Introduction • Ammonia received its official name as "ammoniac" in 1787 from the

Latin name of “ammonium chloride - sal ammoniac”; because that

salt was obtained near the temple of Egyptian god Amon.

• ammonia was first isolated by Joseph Priestley in 1774 and was

termed by him "alkaline-air". Eleven years later in 1785, Claude

Louis Berthollet ascertained its composition.

• The Haber–Bosch process to produce ammonia from the nitrogen in

the air was developed by Fritz Haber and Carl Bosch in 1909 and

patented in 1910.

• It was first used on an industrial scale in Germany during World War

I. The ammonia was used to produce explosives to sustain war efforts.

Properties of Ammonia

• Molecular weight : 17 gm/mol

• Boiling point : -33.34 ˚C

• Freezing point : -77.7 ˚C

• Standard heat of formation: -46 222 KJ/Kmol

• Solubility : Soluble In chloroform, ether, ethanol

• Density : 0.769 Kg/𝑚3 At STP

Uses of Ammonia

Refrigerant

Industry

Preservative

Transport of 𝐻2

Metal treatment

Lab reagent

Solvent

Medicine & Cosmetics

Uses of Ammonia In Industries

Fertilizer Industry

Petroleum Industry

Mining Industry

Rubber Industry

Paper Industry

Leather Industry

MANUFACTURING PROCESSES

• The synthesis gas for manufacture of Ammonia is produced by

steam reforming or partial oxidation of Hydrocarbon feed.

• The various processes used commercially in industries for

production of Ammonia are :

1. Imperial chemical Industries (ICI)

2. Haber–Bosch Process

3. Braun Purifier Process

1. Imperial chemical Industries (ICI)

• Hydrocarbon feed is subjected to steam reforming in two

stages to form oxides of Carbon, methane and hydrogen.

• In the secondary reformer air is mixed with the gases to get a

N2 : H2 ratio of 1:3.

• Carbon monoxide is removed by shift conversion. Carbon

dioxide is removed by absorption into or Potassium Carbonate

solution.

• Traces of CO and CO2 are removed by conversion into

methane. Synthesis gas is used to produce ammonia.

Advantages of ICI Process

• Intensive heat recovery

• Generation of steam which can be imported.

• Less dependency on electricity

• Capital cost is least.

2. Haber – Bosch Process

• The Haber–Bosch process, is the industrial implementation of

the reaction of nitrogen gas and hydrogen gas. It is the main

industrial procedure to produce ammonia:

N2 + 3 H2 → 2 NH3 (ΔH = −92.4 kJ·mol−1)

A Flow Scheme of Haber Process

Process flow Diagram

Parameters • Temperature: 450˚C, moderately high. Using a lower temperature would

increase yield at equilibrium, but the reactions would be too slow. The

temperature is a compromise between rate and position of equilibrium.

• Pressure: 200-1000 atm. Pressure is beneficial in terms of rate and

position of equilibrium, so a very high pressure is used. The pressure is not

even higher as the cost of maintaining it is more than the value of the extra

ammonia that would be made.

• Catalyst: Iron, As the rates are increased, the temperature used need not be

so high as that which would be required in the absence of a catalyst. By

allowing a lower temperature to be used, the position of equilibrium is more

favourable as the Haber process is exothermic in the forward direction.

Major Engineering Problems

• Reaction kinetics and equilibrium :

• As per Le Chatelier principle for exothermic reaction lower temp

favour the forward reaction and for decreasing moles the higher

pressure is favourable.

• From graph (1) & (2) the equilibrium yield of NH3 is increased by

increase in pressure and decrease in temperature.

• Catalyst :

• All catalyst based on FeO. Nowadays promoters like oxides of

Al, Zr, K are added to make the catalyst more porous and to

withstand the high temperature.

• Space velocity :

• It is the volume of gases at standard condition that passed over

the catalyst bed per unit time with increase in space velocity.

• The % NH3 will decrease most industries uses space velocity

of 10000-20000 per hour.

3. Braun Purifier Process

• In this process Synthetic ammonia (NH3) refers to ammonia

that has been synthesized from natural gas. Natural gas

molecules are reduced to carbon and hydrogen. The hydrogen

is then purified and reacted with nitrogen to produce ammonia.

Chemical Processes

Simple Block Diagram

• The first stage is purification where impurities, mainly sulphur

compounds, are removed from the gas stream.

• Steam reforming is performed in two stages. In the primary stage,

the endothermic reactions take place at pressures around 30 bar and

temperatures of 800°C or higher. This is followed by an exothermic

secondary reformer where air is added to the partially reformed gas

stream.

• The carbon monoxide in the gas leaving the secondary reformer is

converted to carbon dioxide in the shift reactors and then removed

by scrubbing from the gas stream. Any residual carbon oxides are

then converted back to methane by methanation before compression

of the hydrogen and nitrogen to ammonia synthesis pressure.

• The final reaction stage is ammonia synthesis where the hydrogen

and nitrogen combine to form ammonia. This reaction stage takes

place at high pressure (100-350 bar) and is highly exothermic.

Ammonia Industries in India

• Indian Farmers Fertilizer Cooperative Ltd.

• Gujarat State Fertilizers Cooperative Ltd.

• Deepak Fertilizers & Petrochemicals Cooperative Ltd.

• Southern Petrochemical Industries Cooperative Ltd.

• Zuari Agro Chemicals Ltd.

Reactor for Ammonia Synthesis

References

[1] https://news.slac.stanford.edu/image/haber-bosch-process

[2] http://en.wikipedia.org/wiki/Haber_process

[3]http://www.chemguide.co.uk/physical/equilibria/haber.html

[4]http://www.sbioinformatics.com/design_thesis/Ammonia/Am

monia_Methods-2520of-2520Production.pdf