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Industrial implementation of the ammonia synthesis - How does it work?

In September 1913, the first industrial-scale ammonia production plant came on stream at BASF in Ludwigshafen. The Haber-Bosch process for ammonia synthesis, which was first successfully operated at BASF Ludwigshafen in September 1913, was the decisive step into the age of mineral fertilizers. This innovation became a key driver in the development of the industrialized society and is still securing the nutrition of billions of people today.

The foundations for the "Synthesis of ammonia from its elements" were laid by Professor Fritz Haber from 1904 onwards with his work at Karlsruhe Institute of Technology. The industrial upscaling of ammonia synthesis entrusted by BASF to Carl Bosch in 1909, however, initially raised unforeseen problems. Because the high-pressure process required pressures and temperatures considerably exceeding those that had so far been technically possible. The first plants couldn't stand the strain and its steel reactors burst. Bosch the chemist, who was experienced in metallurgy, closely studied the metals that had been used and finally identified the cause: the hot, highly pressurized hydrogen was taking the carbon essential for strength out of the steel walls, making them soft and simultaneously brittle. Bosch overcame this challenge by fitting the inside of the apparatus with a thin lining of low-carbon soft iron and drilling holes in the pressure bearing steel wall. This allowed the hydrogen that had penetrated into the material to escape without causing damage. This innovative high pressure technology required further components that were not available anywhere, and had to be designed and tested within the company. BASF established the chemical industry's first material testing facility for this purpose in 1912.

The reactor of the newer ammonia production plant in which the synthesis gas mixture reacts over a catalyst bed at above 400 degrees Celsius and more than 150 bar pressure to produce ammonia, has a 15 centimeter thick wall of high-strength steel. Its advanced alloy resists the pressurized hydrogen, making the legendary casing unnecessary today.

The raw material used to generate the synthesis gas is also different today: in the first few decades of the Haber-Bosch process, a large number of employees prepared a bed of glowing coke and passed steam over it. Today, ammonia plants use natural gas as a feedstock and energy source, which also makes up the lion's share of the production costs. At Ludwigshafen site, the ammonia production is the second largest natural gas consumer after the company's own power generating plants. As in the early days, the necessary nitrogen is obtained from the air supply and, for a change, costs nothing at all.

Topics:
  • nitrogen fixation
  • Haber-Bosch process
  • catalysis
  • Fritz Haber
  • ammonia
  • synthesis gas
  • Carl Bosch
More about BASF
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