Haber Process

World situation

At the beginning of the 20th century, nitrates were in high demand for both agricultural fertilisers and for nitric acid which is used mainly for explosive production. However at this time the only source of nitrates for the production of these entities was from natural deposits such as that available in Chile, where the guano (bird droppings which contained fish whose muscles decompose into nitrates) are located, 1.5m high and 350 km long. As world population increased, so did the use of fertilizers. Using fertilizer with high nitrogen content provided a good crop yield. This caused some scientists in the 19th century to begin to worry about the depletion of the sources of nitrogen for chemical fertilizer.

At the beginning of the 20th century Europe's growing population had created a demand for an increase in agricultural production. Nitrates, used in industrial fertilizer, required ammonia for their manufacture. However, there was a shortage of naturally occurring, nitrogen-rich fertilisers, and so as a result of this there was much research into how ammonia could be produced from atmospheric nitrogen.

These conditions prompted the German Chemist Fritz Haber, to develop the industrial synthesis of ammonia by combining the nitrogen in the air with hydrogen to form ammonia.

Haber and chemistry/technicalities of process

Prior to WWII Haber had demonstrated how nitrogen and hydrogen could be combined to form ammonia. However yield was too small to be economically viable despite the experiment using 1000Ð'oC and a catalyst. This formed an extremely inefficient and unusable experimental design. Following much frustration many scientists identified that Haber had failed to consider the pressure of the gases in his experimental design. This instigated Haber to conduct a full investigation into the production process. He also considered the effects of temperature, pressure and catalyst in an attempt to make the process much more economically viable. This investigation allowed Haber to conclude the perfect conditions for the process. These conditions prompted the German Chemist Fritz Haber, to develop the industrial synthesis of ammonia by combining the nitrogen in the air with hydrogen to form ammonia.

By 1905, Haber had been able to make a small amount of ammonia from nitrogen and hydrogen at a temperature of 1000Ð'oC using an iron catalyst. Research continued and in 1909 Fritz Haber established the conditions under which nitrogen gas and hydrogen gas would combine. He determined the following conditions were required:

пÑ"? Medium temperature (500Ð'oC)

пÑ"? Very high pressure (250 atmospheres, 351kPa)

пÑ"? A catalyst (a porous iron catalyst prepared by reducing magnetite, Fe3O4).

This process produced an ammonia yield of approximately 10-20%.

Haber had thus established the conditions for large scale synthesis of ammonia by 1909 and the process was handed over to Carl Bosch for industrial development. The German industry also developed the high pressure equipment necessary to run the process and so by 1913 30 tonnes of ammonia was being produced a day.

Evaluate its significance at the time in world history

In the Haber process nitrogen (N2) and hydrogen (H2) gases are reacted over an iron catalyst (Fe3+) usually magnetite, in which aluminium oxide (Al2O3) and potassium oxide (K2O) are used as promoters. The reaction is carried out under conditions of 250 atmospheres, 450-500Ð'oC which results in a yield of 10-20%. The reaction is:

The Haber process was patented in 1910. This was a time when there was a large demand for ammonia and so the Haber process was used to produce ammonia which was used predominately to produce fertilisers. This helped to feed the rapidly growing world population at the time since it was easier and cheaper to grow crops due to the newly developed Haber process. Prior to the development of the Haber process there was only one source of nitrogen which was Chile. The start of World War I was looming and nitrogen compounds were essential for the production of fertilisers and explosives. Much of the fertiliser originated in Chile however, which was a long way from the industrial