Dr. Dmitri Kopeliovich

Ammonia cracking is a process of dissociation of gaseous anhydrous Ammonia (NH₃) into a mixture of Hydrogen (H₂) and Nitrogen (N₂) according to the reaction:

2NH₃ = N₂ + 3H₂
The reaction is endothemic, requiring 383 kJ/mol. The process is performed at increased temperature within the range 1560-1740ºF (850-950ºC) in the presence of nickel as catalyst.

The resulting gas mixture is composed of hydrogen and nitrogen in the proportion 3:1 (75% of H₂ and 25% of N₂) with very little amount (20 -100 ppm) of residual undissociated ammonia with dew point -60ºF to -20ºF (-51ºC to -29ºC). The gas may be further purified by molecular sieves purifier resulting in reducing the uncracked ammonia to 1-3 ppm with dew point -110ºF (-80ºC).

The principal flow scheme of ammonia cracker is presented in the figure:



Ammonia cracking is a simple and cost effective method of manufacturing hydrogen, however it may be used only in the applications, in which presence of nitrogen is acceptable.

The main applications of ammonia cracker:

• Annealing furnaces with reducing atmosphere for continuous heat treatment of cold rolled steel.
• Bell type annealing furnaces.
• Sintering of metals.
• Metal powder annealing.
• Brazing.
• Hydrogenation of oil.

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• Argon
• Ammonia
• Nitrogen membrane generator

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