Nitrogen-fixation processes

By now, Haber was cut off from all but a handful of friends and colleagues. Few academic associates visited or sent words of sympathy, although such gestures would have cost them nothing. The chemical industry, which owed Haber much of its success, had allied itself with the Nazis. Carl Bosch, Haber s old colleague in the nitrogen-fixation process, was the only industrialist who tried to help. 

Haber s legacy, like his life, was a mix of high-minded science and nationalism gone tragically amiss. To obliterate Haber s achievements, the Nazis credited others with his nitrogen-fixation process and his chemical warfare work. Most horrifically, the Nazis used the pesticide Zyklon B—an offshoot of work begun in Haber s institute and supported by him—in concentration camp gas chambers. Among Haber s relatives, members of his stepsister s family lost their lives to Zyklon B cyanide at Auschwitz. 

A class of plants, called legumes, has bacteria which extract N2 directly, converting it to NH3. This nitrogen fixation process, catalyzed by an enzyme produced by the bacteria, is highly efficient at usual temperatures and pressures. 

Serpek A nitrogen fixation process using aluminum nitride. A mixture of bauxite and coke is heated in nitrogen at 1,800°C to produce aluminum nitride this yields ammonia on hydrolysis by boiling with aqueous potassium aluminate ... 

Nitrogen fixation is the process by which nitrogen is taken from its relatively inert molecular form in the atmosphere and converted into nitrogen compounds useful for other chemical processes. Hydrogen gas is also released during the biological nitrogen fixation process. 

The biological nitrogen fixation process is Introduced. Discussion focusses on the Dominant Hypothesis of nitrogenase composition and functioning. The enzyme system catalyzes the six-electron reduction of N2 to 2 NH3 concomitant with the evolution of H2. ATP hydrolysis drives the process. The two protein components of the enzyme,... 

Birkeland Eyde Process. See under Nitrogen Fixation Processes... 

Table 1 summarizes several redox transformations that can be accomplished in artificial photosynthetic assemblies including the photolysis of water, carbon dioxide reduction, and nitrogen fixation processes. The endoergicities of these transformations, and the number of electrons involved in the reduction processes, are also indicated in the table. It is evident that the energy per electron to drive the various transformations are met by visible light quanta. 

Since no economical nitrogen fixation process that starts with nitrogen oxides has been discovered, ammonia has developed into the most important building block for synthetic nitrogen products worldwide. Prior to World War II, ammonia production capacity remained relatively stable. But during the war the need for explosives caused an increase in the production of ammonia for nitric acid manufacture. Then, after the war, the ammonia plants were used to manufacture fertilizers. As a result, there was a rapid increase in fertilizer consumption. The advantages of fertilizers were emphasized, and production capacity increased by leaps and bounds. 

Because no economical nitrogen fixation process that starts with nitrogen oxides has been discovered, ammonia has developed into the most important building block for synthetic nitrogen products. Anhydrous ammonia is produced in about 80 countries.36... 

Tim, B. and Danz, W., 1964. History of nitrogen fixation processes. In Vincent Sachelli (Editor). Fertilizer Nitrogen, Its Chemistry and Technology. ACS Monograph No. 161, Reinhold, New York, NY, pp. 40—57. 

Due to the mild conditions under which it occurs, the biological nitrogen-fixation process may seem inherently simpler than the industrial one. However, it is not the biological process displays a complexity that belies the simplicity of the chemical conversion of N2 2NH3. Genetic analysis reveals that... 

In the following section we discuss the problem of contamination by adventitious ammonia and discuss how the use of isotope labelling could lead to a clearer picture of the reported photochemical nitrogen fixation process. 

Despite many studies there is available, at this time, no unequivocal report of artificial photocatalytic synthesis of ammonia from nitrogen and water on heterogeneous catalysts. The chemical reaction 1, shown at the beginning of this chapter, remains speculative 17 years after it was initially reported. No rational start has yet been made on determining a mechanism for the reported nitrogen fixation process, despite the fact that a clear demonstration and understanding of any such process would be of great importance. Despite 17 years of research, the reported yields of ammonia from artificial photosynthesis remain at or near the limits of detection by routine analytical methods. As we stated earlier in this chapter, the concept of a major discovery that remains forever on the borderline of detectability is internally contradictory. The current state of the field is one where serious scientific skepticism is appropriate. 

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