Producing the Feedstocks and Oxidizing Ammonia

Given BASF s dependence on coal, Bosch decided that the sole eligible source of hydrogen was water gas prodnced by the reaction of glowing coke with water vapor  

The gas contains about 50% H, 40% CO, and 5% each of N and CO2, and the cryogenic process was used initially to condense CO out of the gas at 200 °C and 2.5 MPa. As the volume of ammonia synthesis increased, Bosch sought a better solution. In the summer of 1911 Wilhelm Wild (1872-1951), one of Nernst s pnpils working at BASF, proposed a cheaper method of hydrogen production from water gas a catalytic process during which the reaction of CO with water shifts the gas to CO2 and produces additional H2 for ammonia synthesis. 

The next step was to wash both gases with water in towers and mix them before circulating them over activated charcoal to remove H2S. Running the gas production processes together with the appropriate air steam ratio will produce synthesis gas with the correct stoichiometric ratio. The key segment of the process came next a catalytic conversion, a shift reaction transforming CO and steam into CO2 in the 

CO2 was then removed in a water scrubber at 2.5 MPa. Removing the residual amount of CO (2-3%) turned out to be an unexpected challenge. Bosch chose scrubbing under a pressure of at least 20 MPa in a solution of cuprous oxide (CU2O), but it was corroding any iron surface with which it came in contact. Replacing numerous iron parts with more expensive metal was unthinkable. 

for once dejected and under strong pressure by the company s directors, turned to Carl Krauch (1887-1968), a young chemist on his team. Krauch solved this last complication on the road to commercial ammonia synthesis by adding ammonia to the solution. Cuprous ammonium formate proved to be an excellent absorber of CO, and Krauch s solution remained in use for decades. The remaining moisture was not removed from the mixture used in the first two commercial plants, but it is taken out in modern processes.If the purified mixture contained excess H, its content was adjusted with nitrogen from liquefied air to the exact stoichiometric ratio of 1 3. 

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