The Haber Process

A detailed Summary of The Haber Process

During the first decade of the twentieth century the world-wide demand for ammonia for use in fertilisers (in the form of nitrates) and in the production of explosives for use in mining and warfare could only be satisfied on a large scale from deposits of guano in Chile (2). Though this deposit was of huge size (approximately five feet thick and 385 kilometres long) it represented a rapidly depleting resource when compared to world-wide demand. As a result of this there was much research into how ammonia could be produced from atmospheric nitrogen. The problem was eventually solved by Fritz Haber (1868 - 1934) in a process which came to be known as the "Haber Process" or the "Haber - Bosch Process".

Haber developed a method for synthesising ammonia utilising atmospheric nitrogen and had established the conditions for large scale synthesis of ammonia by 1909 and the process was handed over to Carl Bosch for industrial development (1). the reaction is a simple equilibrium reaction which occurs in gaseous state as follows;

N2 (g) + 3H2 (g) = 2NH3 (g) heat of enthalpy = -92.6 kJ/mol

In predicting how to obtain the highest yield from this reaction we must refer to Le Chatlier's Principle. Th

The Haber process has been used since its discovery to produce ammonia which has been used predominately to produce fertilisers which have helped to feed a rapidly growing world population and has been one of the main props used to avoid world-wide famine. The increase in the use of nitrogen based fertilisers is demonstrated in Appendix 2.

4. Micro-organism's in Action. J M Lynch & J E Hobbie. Blackwell Publication 1998

Faced with this failure to find conditions suitable for an industrial process Haber began to experiment to find a catalyst that would facilitate the reaction. A catalyst is a substance that reduces the activation energy of a reaction, thus increasing the speed at which the reaction occurs, or in the case of equilibrium reactions the speed at which equilibrium is reached. After hundreds of experiments Haber discovered that a fast enough reaction with a high enough yield of ammonia would occur with a pressure between 200 and 400 atmospheres and at a temperature between 670K and 920K in the presence of a catalyst of iron (in the form of iron filings to increase its active surface area) plus a few percent of oxides of potassium and aluminium. This process was first demonstrated in 1909 and patented as the Haber Process in 1910 (3).

As a result of this work is now underway to both try to solve the problem of the high energy consumption of the Haber Process and to reduce our reliance on chemical fertilisers.

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Approximate Word count = 1201
Approximate Pages = 5 (250 words per page double spaced)

Category: Science