The Haber process
The raw materials for the process of making ammonia are hydrogen and nitrogen.
Hydrogen is obtained by reacting A naturally occurring hydrocarbon gas mixture. (mostly A colourless gas that can do harm to life forms.) with steam, or from The breaking down of large hydrocarbon molecules into smaller, more useful hydrocarbon molecules by vaporising them and passing them over a hot catalyst. oil In fractional distillation, such as that of crude oil, the different parts of the original mixture are called fractions. The substances in each fraction have similar boiling points to each other..
CH4 + 2H2O 鈫 CO2 + 2H2
Nitrogen is obtained from the air. Air is 78 per cent nitrogen and nearly all the rest is oxygen. When hydrogen is burned in air, the oxygen combines with the hydrogen leaving nitrogen behind.
In the Haber process, nitrogen and hydrogen react together under these conditions:
- a high temperature 鈥 ranging from 350掳C to 450掳C
- a high pressure 鈥 ranging from 150 to 200 A unit of pressure. (150 鈥 200 times normal pressure)
- an iron A substance that changes the rate of a chemical reaction without being changed by the reaction itself.
In addition, any unreacted nitrogen and hydrogen are recycled. The reaction is reversible. In a chemical equation, the symbol 鈬 is used instead of an ordinary arrow if the reaction is reversible:
This equation summarises the Haber process:
nitrogen + hydrogen 鈬 ammonia
N2 + 3H2 鈬 2NH3
| Stage one | Having obtained the hydrogen and nitrogen gases (from natural gas and the air respectively), they are pumped into the compressor through pipes. |
| Stage two | The gases are pressurised to about 200 atmospheres of pressure inside the compressor. |
| Stage three | The pressurised gases are pumped into a tank containing beds of iron catalyst at about 450掳C. In these conditions, some of the hydrogen and nitrogen will react to form ammonia. |
| Stage four | The unreacted nitrogen and hydrogen, together with the ammonia, pass into a cooling tank. The cooling tank liquefies the ammonia, which can be removed into pressurised storage vessels. |
| Stage five | The unreacted hydrogen and nitrogen gases are recycled by being fed back through pipes to pass through the hot iron catalyst beds again. |
| Stage one |
|---|
| Having obtained the hydrogen and nitrogen gases (from natural gas and the air respectively), they are pumped into the compressor through pipes. |
| Stage two |
|---|
| The gases are pressurised to about 200 atmospheres of pressure inside the compressor. |
| Stage three |
|---|
| The pressurised gases are pumped into a tank containing beds of iron catalyst at about 450掳C. In these conditions, some of the hydrogen and nitrogen will react to form ammonia. |
| Stage four |
|---|
| The unreacted nitrogen and hydrogen, together with the ammonia, pass into a cooling tank. The cooling tank liquefies the ammonia, which can be removed into pressurised storage vessels. |
| Stage five |
|---|
| The unreacted hydrogen and nitrogen gases are recycled by being fed back through pipes to pass through the hot iron catalyst beds again. |
The reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. The mixture is cooled and compressed, causing the ammonia gas to Condensation is a change of state in which gas becomes liquid by cooling. into a liquid. The liquefied ammonia is separated and removed. The unreacted nitrogen and hydrogen are then recycled back into the A container in which chemical reactions are carried out, often on an industrial scale..