Industrial fixation

Dinitrogen is fixed either by natural processes or by industrial ammonia (qv) production (1,8,9). The estimates for the aimual biological contribution range around 100-200 x 10 t. Industrial fixation contributes about 50 x 10 t/yr for fertilizer uses (see Fertilizers). Other processes, eg, lightning and combustion, are estimated to fix about 30 x 10 t/yr. Thus the biological process represents the majority (ca 65%) of the total aimual fixation rate, contributing about three times as much as the commercial production of fertilizer. 

Figure 11.2 Distribution of nitrogen in the biosphere and annual transfer rates can be estimated only within broad limits. The two quantities known with high confidence are the amount of niirogcn in the atmosphere and the rate of industrial fixation. The inventories (within the boxes) are expressed in terms of 10 tonnes of N the transfers (indicated by arrows) are in 10 tonnes of N. Taken from ref. 7 with some adjustments for more recent data.

Before 1900 the large-scale production of nitric acid was based entirely on the reaction of concentrated sulfuric acid with NaNOa and KNOj (p. 407). The first successful process for making nitric acid directly from Ni and O2 was devised in 1903 by E. Birkeland and S. Eyde in Norway and represented the first industrial fixation of nitrogen ... 

Most chemical reactions give off heat and are classified as exothermic reactions. The rate of a reaction may be calculated by the Arrhenius equation, which contains absolute temperature, K, equal to the Celsius temperature plus 273, in an exponential term. As a general rule, the speed of a reaction doubles for each 10°C increase in temperature. Reaction rates are important in fires or explosions involving hazardous chemicals. A remarkable aspect of biochemical reactions is that they occur rapidly at very mild conditions, typically at body temperature in humans (see Chapter 3). For example, industrial fixation of atmospheric elemental nitrogen to produce chemically bound nitrogen in ammonia requires very high temperatures and pressures, whereas Rhizobium bacteria accomplish the same thing under ambient conditions. 

Nitrogen is the most abundant uncombined element in the earth s surface. It is one of the four essential elements (C, H, O, N) that support all forms of life. It constitutes, on the average, about 15% by weight in proteins. The industrial fixation of nitrogen in the production of agricultural fertilizers and other chemical products is now carried out on a vast scale. 

Haber, F. (1868-1934). Synthesized ammonia from nitrogen and hydrogen, the first industrial fixation of... 

R. Lovejoy, and erected a large works at Niagara Falls, New York, The industrial fixation of atniospheric nitrogen thus had its birth in the United States,... 

Industrial fixation occurs through reactions such as the Haber-Bosch reaction. 

Nitrogen fixation occurs naturally by chemical and/or biological processes, or by commercially-important chemical syntheses. Estimates place the biological processes as by far the major contributor of some 122 X 10 tonnes per annum globally, while lightning and combustion add a further 30 x 10 tonnes, with industrial fixation realizing some 50 x... 

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