but academic progress to harness the apparent simplicity of this reaction was
laboured, and even in the earliest history
14 of this problem it became apparent
that to tease these two elements to combine, temperature, pressure, and
catalysis were all important.
Nitrogen was known to combine with hydrogen to form ammonia as early
as 1784—Claude-Louis Berthollet even determined the approximate ratio of
the two constituents in the compound. By 1788 high temperature synthesis
(by passing nitrogen and hydrogen—or water vapour—over red-hot iron or
glowing coals) had been attempted and then repeated by more than a dozen
chemists during the nineteenth century. The effect of pressure was firstly
examined in 1811 by George Friedrich Hildebrand who, after a failed attempt
to combine the elements at atmospheric pressure, submerged a sealed flask
containing a mixture of the gases in the sea to a depth that achieved a pressure
of 3.1 MPa (about 30 atmospheres)—with little effect. The first recorded use
of a catalyst dates from 1823 when Johann Wolfgang Döbereiner experimented with platinum, and by the 1870s many other different metals and
compounds had been tested and indeed patented. Henri Saint-Claire Deville
apparently also managed some form of fixation in 1865.
The first ‘modern’ examination of the reaction was undertaken by William
Ramsay and Sidney Young in Bristol in 1884 who studied the decomposition
of ammonia at atmospheric pressure in the presence of an iron catalyst at
800 °C, the template later used by Haber and van Oordt. By the term
‘modern’ we mean one which understood that a chemical equilibrium was
probably involved and which benefited from the supreme practical expertise
of the workers. The clear conclusion from their experiment however was that
the equilibrium position for the synthesis of ammonia lay far to the left.
Numerous attempts at ammonia synthesis followed during the 1880s and
1890s but all were fruitless and then, at the turn of the century, the problem
was effortlessly solved by a giant of German physical chemistry, Wilhelm
Ostwald.
Ostwald was not only a perceptive scientist but also a perceptive statesman
in that he long realised that the naval supremacy of the British would deny
Germany fixed nitrogen for her fertilisers and munitions if the antagonism of
the Boer War were to escalate into a full-scale conflict—fears which were later
realised in 1914 but for different reasons. So, in 1900 he announced a
solution to this national threat when he notified Fabwerke Hoechst and BASF
that he had succeeded in synthesising ammonia from its elements using an
iron catalyst at atmospheric pressure. The low cost of this process both in
terms of materials and energy would clearly revolutionise the supply of
Germany’s fixed nitrogen making her completely free of the saltpetre trade—
88
D. Sheppard
laboured, and even in the earliest history
14 of this problem it became apparent
that to tease these two elements to combine, temperature, pressure, and
catalysis were all important.
Nitrogen was known to combine with hydrogen to form ammonia as early
as 1784—Claude-Louis Berthollet even determined the approximate ratio of
the two constituents in the compound. By 1788 high temperature synthesis
(by passing nitrogen and hydrogen—or water vapour—over red-hot iron or
glowing coals) had been attempted and then repeated by more than a dozen
chemists during the nineteenth century. The effect of pressure was firstly
examined in 1811 by George Friedrich Hildebrand who, after a failed attempt
to combine the elements at atmospheric pressure, submerged a sealed flask
containing a mixture of the gases in the sea to a depth that achieved a pressure
of 3.1 MPa (about 30 atmospheres)—with little effect. The first recorded use
of a catalyst dates from 1823 when Johann Wolfgang Döbereiner experimented with platinum, and by the 1870s many other different metals and
compounds had been tested and indeed patented. Henri Saint-Claire Deville
apparently also managed some form of fixation in 1865.
The first ‘modern’ examination of the reaction was undertaken by William
Ramsay and Sidney Young in Bristol in 1884 who studied the decomposition
of ammonia at atmospheric pressure in the presence of an iron catalyst at
800 °C, the template later used by Haber and van Oordt. By the term
‘modern’ we mean one which understood that a chemical equilibrium was
probably involved and which benefited from the supreme practical expertise
of the workers. The clear conclusion from their experiment however was that
the equilibrium position for the synthesis of ammonia lay far to the left.
Numerous attempts at ammonia synthesis followed during the 1880s and
1890s but all were fruitless and then, at the turn of the century, the problem
was effortlessly solved by a giant of German physical chemistry, Wilhelm
Ostwald.
Ostwald was not only a perceptive scientist but also a perceptive statesman
in that he long realised that the naval supremacy of the British would deny
Germany fixed nitrogen for her fertilisers and munitions if the antagonism of
the Boer War were to escalate into a full-scale conflict—fears which were later
realised in 1914 but for different reasons. So, in 1900 he announced a
solution to this national threat when he notified Fabwerke Hoechst and BASF
that he had succeeded in synthesising ammonia from its elements using an
iron catalyst at atmospheric pressure. The low cost of this process both in
terms of materials and energy would clearly revolutionise the supply of
Germany’s fixed nitrogen making her completely free of the saltpetre trade—
88
D. Sheppard