Evolution of Ammonia Synthesis

Nearly a century after its invention the Haber-Bosch process of ammonia synthesis from its elements remains fundamentally unchanged, yet at the same time radically transformed (fig. 6.1). This is only a seemingly contradictory statement while Haber and Bosch would have the satisfaction of recognizing the essentials of their creation in today s modern ammonia plants, they would be amazed at the size of individual operations and at their efficiency, and they would certainly admire many innovations, large and small, that have made ammonia synthesis into one of the most remarkable industrial undertakings of modern civilization.  

Classical Haber-Bosch process of ammonia synthesis. 

Global production of ammonia-based nitrogen fertilizers, 1945-1998. 

Oppau did not produce any nitrogen fertilizer during the last year of World War I because all of its ammonia was used to synthesize HNO3 for Germany s munitions industry. Ammonium sulfate production at the plant resumed only in June 1919, and output reached almost 13,000 t during the remainder of the year, increasing to more than 92,000 t in 1920. On September 21, 1921, a major explosion of ammonium nitrate and ammonium sulfate stored in a silo destroyed a large part of the plant and killed 561 people in spite of this setback, that year s output of ammonium sulfate surpassed 190,000 t and in 1922 rose to 303,000 t.  

The first transfer of the Haber-Bosch process abroad was a result of the Versailles Treaty, which the defeated Germany had to sign in 1919. By its terms, BASF was obliged to license construction of an ammonia plant with an annual capacity of 

---

A convenient laboratory synthesis of high purity CA is hydrolysis of cyanuric chloride (7). On a commercial scale, CA is produced by pyrolysis of urea [57-13-6]. When urea is heated at - 250 ° C for about an hour, it is converted to crude CA with evolution of ammonia. 

The sodium and ammonium analogs of the potassium compound can be prepared by the same procedure as described for the synthesis of the potassium compound. Both of the alkali metal compounds are hygroscopic in nature. The ammonium derivative cannot be obtained in a pure condition, because of its continuous evolution of ammonia and carbon dioxide. 

Lithium reacts with acetylene in liquid ammonia solution to give the mono and dilithium acetylides, LiC=CH and LiC=CLi, with the evolution of hydrogen, which illustrates the slight acidity of acetylene. One commercial use of LiC=CI I is in one step of the synthesis of vitamin A. 

CI2 evolution reaction, 38 56 electrochemical desorption, 38 53-54 electrode kinetics, 38 55-56 factors that determine, 38 55 ketone reduction, 38 56-57 Langmuir adsorption isotherm, 38 52 recombination desorption, 38 53 surface reaction-order factor, 38 52 Temkin and Frumkin isotherm, 38 53 real-area factor, 38 57-58 regular heterogeneous catalysis, 38 10-16 anodic oxidation of ammonia, 38 13 binding energy quantification, 38 15-16 Haber-Bosch atrunonia synthesis, 38 12-13... 

For pore diffusion resistances in reactions having moderate heat evolution, the following phenomena characteristically hold true in industrial ammonia synthesis [212] in the temperature range in which transport limitation is operative, the apparent energy of activation falls to about half its value at low temperatures the apparent activation energy and reaction order, as well as the ammonia production per unit volume of catalyst, decrease with increasing catalyst particle size [211], [213]-[215]. For example at the gas inlet to a TVA converter, the effective rate of formation of ammonia on 5.7-mm particles is only about a quarter of the rate measured on very much smaller grains (Fig. 13) [157]. 

The story of the evolution of life on Earth is relatively straightforward in comparison to the problem of how it first arose. The abiotic synthesis on Earth of the organic compounds necessary for the creation of life appears to require a reducing atmosphere (see Box 1.5). Early experiments with electrical discharges in mixtures of methane, ammonia and hydrogen sulphide in the presence of water created various organic compounds es-... 

X-ray diffraction can be used to identify the phases which are present in a catalyst. To follow the evolution of a catalyst during pretreatment or catalytic reaction (ammonia or methanol synthesis), in situ XRD experiments have been performed. For this purpose Nix et al. (1987) have built a high-pressure XRD cell operating up to 50 bar and temperatures up to 700 K. The reactant gases flow over the catalysts sample heated by conduction from a cartridge heater. The temperatures are measured and controlled using a thermocouple fixed into the copper support block (fig. 3). 

---