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The Modern Ammonia Plant
The Haber process is not the only catalytic reaction involved in modern ammonia production, and improved chemical engineering of all the steps has led to a big reduction in the energy needed to produce ammonia.
Energy Cost of Ammonia Production
barchart: energy used per tonne of ammonia manufactured
The feedstock today in the UK is natural gas, air and steam. Several steps are needed, using a range of different catalysts. The separate processes are listed.
  • Purification of natural gas to remove sulphur compounds



  • Reaction of methane and steam
    CH4(g) + H2O(g) CO(g) + 3H2(g)
    and unreacted CH4

  • Oxygen from the air reacts with some of the hydrogen
    2H2(g) + O2(g) 2H2O(g)
    The resulting steam and heat converts most of the remaining methane
    CH4(g) + H2O(g) CO(g) + 3H2(g)


  • Removal of carbon monoxide by mixing gases with steam
    CO(g) + H2O(g) CO2(g) +H2(g)


  • Removal of CO2 by reaction with a base, followed by removal of last traces of CO and CO2 by reaction with H2 to give methane and steam.


  • The gas mixture entering the ammonia reactor is
    74 % hydrogen, 25 % nitrogen, 1 % methane

    N2(g) + 3H2(g) 2NH3(g)

A balanced equation for the overall process is

7CH4 + 8N2 + 2O2 + 10H2O 7CO2 + 16NH3

The whole operation is integrated and continuous. Other than ammonia the only outputs are waste heat, and carbon dioxide. The carbon dioxide can be collected and sold.

Question

Why is this necessary?

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Catalyst: cobalt and nickel oxides on alumina support
Catalyst: nickel oxide on calcium aluminate support
Catalyst: iron oxide
Catalyst: nickel
Catalyst: promoted iron
Catalyst: nickel

Question

If you were looking for a new catalyst to do better than iron what metals would you consider?

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