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| Manufacture of Ammonia Habers Process |
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| Fritz Haber |
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| Ammonia is prepared commercially in vast quantities. The major method of production is the Haber process invented by Fritz Haber, in which nitrogen is combined directly with hydrogen at high temperatures and pressures in the presence of a catalyst. |
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| Reaction |
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| Reactants |
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| Nitrogen: Hydrogen ( 1:3 by vol ). |
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| Nitrogen is easily obtained from air by fractional distillation. |
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| (Air is almost 80% nitrogen). |
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| Hydrogen is obtained from water gas (Bosch Process) or from natural gas (methane). The hydrocarbon is reacted with steam. |
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| methane + steam g carbon dioxide + hydrogen. |
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| The reactants should be dry, pure and free from impurities |
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| Conditions for maximum yield of ammonia: |
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 The reaction is reversible. |
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An optimum temperature of 450-500ºC is used. |
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If the temp becomes low, the speed of the reaction is low and the yield of ammonia is low. |
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The reaction being exothermic ,the heat evolved maintains the temp and hence external heating is not required. |
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An optimum pressure of
152000-684000 mm of Hg is used. |
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The reaction proceeds with a decrease in volume, hence the pressure is increased to optimize the forward reaction. |
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| Catalyst |
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| Finely divided Fe is used as a catalyst to accelerate the reaction at optimum temperature. The catalyst is mixed with small amounts of promoter- molybdenum to enhance the efficiency of the catalyst. |
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| Process |
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| Compression Pump: Mixture of N2 and H2
in the ratio 1:3 is compressed to 152000-684000 mm of Hg pressure. |
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| The compressed mixture of N2 and H2 is passed over heated catalyst. Ammonia is formed. Heat exchange takes place between residual N2 and H2 and the incoming unreacted N2 and H2. |
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| Condensor |
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| Mixture of ammonia and residual N2 and H2 under pressure is allowed to expand suddenly through a small nozzle into a region of low pressure. |
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| This results in fall in pressure and ammonia is liquefied and collected at the base. Unreacted N2 and H2 is recycled into the catalytic chamber. |
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