PATHS OF INNOVATORS - Carl Bosch (1874-1940)

Father of chemical engineering

Ammonia, which is an ingredient of fertilizers and explosives (until then in short supply) could not be synthesised during the Eighteenth Century. Carl Bosch adopted Fritz Haber's laboratory method of synthesising ammonia to the industrial scale. He also invented the process for preparing hydrogen on a large scale by passing a mixture of steam and water gas over a catalyst at a high temperature.

CARL BOSCH was born at Cologne, Germany (August 27, 1874) in a family of peasant stock. Even as a boy, he showed a special talent for science and technology which his father encouraged. But he was not allowed to proceed direct to the University for studying Chemistry, till he had first completed a few months of training in an iron works. He obtained in 1898 his doctorate from the University of Leipzig.

Bosch got a job in the Badishe Anilin and Soda Fabrik (BASF), the large company making dyestuffs. He landed, by chance, in a field that would subsequently become his life work.

Between 1902 and 1907, he investigated various nitrogen-fixation processes. He tested the process developed by Wilhelm Ostwald (1853-1932) for producing ammonia from nitrogen and hydeogen and quickly found out the errors committed by Oswald and the reasons for it.

The efforts of chemists to make ammonia from nitrogen and hydrogen failed during the entire 18th century. Fritz Haber (1868-1934), being an excellent theoretician, understood the laws governing chemical reaction and solved this problem.

In 1909, he was able to demonstrate that the reaction of nitrogen and hydrogen to yield ammonia was practicable at a pressure of 150 to 200 atmospheres and in the presence of a catalyst, osmium. This produced only a few drops of ammonia.

Bosch was entrusted with the responsibility to transform Haber's laboratory experiments into large-scale industrial process. He found the catalyst used by Haber was unsuitable. After thousands of experiments, Bosch, in collaboration with his colleagues finally selected a mixture of iron with small amounts of oxides of aluminium, calcium and potassium.

He designed the massive high pressure converters and was the first to use the shift reaction

CO + H2O CO2 + H2

to obtain the large quantity of hydrogen required for the ammonia synthesis.

The gases, nitrogen and hydrogen, had to be obtained in an exceptionally pure state. The separation of the ammonia from the mixture of gases was extremely difficult. Bosch's technical know- how and his leadership proved invaluable.

Bosch had thus successfully completed the largest undertaking in chemical engineering. At the Oppau works the plant was producing 30,000 tons a year of ammonium sulphate.

When BASF and the other German chemical companies merged in 1925 to form the I.G. Farben industrie, Bosch became its chairman.

The Haber-Bosch process has remained unchanged to the present day, for the production of ammonia fertilisers.

Bosch investigated other practical problems: the methanol synthesis used in the manufacture of formaldehyde, carbon hydrogenation and the production of synthetic rubber. Frequent illness prevented him from playing an active role for several years before his death at Heidelberg (April 26, 1940).

Bosch's contribution to chemical engineering was recognised by numerous honorary degrees and the award of the Noble Prize for Chemistry (1931) jointly with Berguis for the discovery of chemical high-pressure methods.

(The Dictionary of Scientific Biography, New York)

R. Parthasarathy

Send this article to Friends by E-Mail

Section  : Science & Tech
Previous : Question Corner
Next     : Noisy Medicine