Ammonia economic importance

The Haber process is the economically important industrial process for making ammonia, NH3, from... 

Brassilexin 48 and sinalexin 49 are among the most potent phytoalexins produced by economically important cruciferous plants. The most efficient preparation of brassilexin 48, sinalexin 49, and analogues 52 reported uses a Vilsmeier formylation-amination of readily available indoline-2-thiones 50 followed by an aqueous ammonia work-up procedure with subsequent oxidation of the 3-(amino)methyleneindoline-2-thione intermediates 51 using iodine in pyridine (Scheme 10) <20010L1213, 2005JOC1828>. The reaction yields are dictated by the efficiency of the... 

Chemical kinetics is a subject of crucial environmental and economic importance. In the upper atmosphere, for example, maintenance or depletion of the ozone layer, which protects us from the sun s harmful ultraviolet radiation, depends on the relative rates of reactions that produce and destroy O3 molecules. In the chemical industry, the profitability of the process for the synthesis of ammonia, which is used as a fertilizer, depends on the rate at which gaseous N2 and H2 can be converted to NH3. 

One of the principal goals of chemical synthesis is to maximize the conversion of reactants to products while minimizing the expenditure of energy. This objective is achieved easily if the reaction goes nearly to completion at mild temperature and pressure. If the reaction gives an equilibrium mixture that is rich in reactants and poor in products, however, then the experimental conditions must be adjusted. For example, in the Haber process for the synthesis of ammonia from N2 and H2 (Figure 13.7), the choice of experimental conditions is of real economic importance. Annual U.S. production of ammonia is about 13 million tons, primarily for use as fertilizer. 

Nitrogen, N2, is very unreactive. The Haber process is the economically important industrial process by which atmospheric N2 is converted to ammonia, NH3, a soluble, reactive compound. Innumerable dyes, plastics, explosives, fertilizers, and synthetic fibers are made from ammonia. The Haber process provides insight into kinetic and thermodynamic factors that influence reaction rates and the positions of equilibria. In this process the reaction between N2 and H2 to produce NH3 is never allowed to reach equilibrium, but moves toward it. 

Although NF3 has been known since 1928, it first became of commercial interest in the late 1950s. Only two processes are of technical and economic importance for the large-scale production of NF3 (1) the electrolysis of molten ammonium hydrogen difluoride, and (2) the direct fluorination of ammonia in the presence of molten ammonium hydrogen difluoride. The electrolytic process has also been recommended and widely used for the preparation of NF3 in the laboratory. 

The development of the catalytic process for ammonia synthesis was already one realization of the desire to manufacture domestic substitutes for economically important imported goods. It is also a common belief among historians of the First World War that without the Haber-Bosch process the German military would have run out of munitions in 1915. Similar intentions led Haber to his wartime partnership with the Raw Materials Department of the War Ministry under Walther Rathenau, which eventually led him to research on chemical means for waging war. As Johnson pointedly summed up the progression the logic of Ersatz led to the problems of munitions, and eventually to poison gas. ... 

Urea Process. In a further modification of the fundamental Raschig process, urea (qv) can be used in place of ammonia as the nitrogen source (114—116). This process has been operated commercially. Its principal advantage is low investment because the equipment is relatively simple. For low production levels, this process could be the most economical one. With the rapid growth in hydrazine production and increasing plant size, the urea process has lost importance, although it is reportedly being used, for example, in the People s RepubHc of China (PRC). 

Only nitrogen and water are produced. However, many factors must be considered such as the coproduction of nitrogen oxides, the economics related to retrofitting of auto engines, etc. The following describes the important chemicals based on ammonia. 

The importance of size on the economics of ammonia production can be seen from Figure 3-1 and Table 3-4, which was developed in 1967 by G. Russell James, general manager of Chemical Engineering Associates (Armonk, N.Y.)4 Before 1969, a 400-tons-per-day plant was large. Now it can barely compete even if it is updated technologically. 

Another important parameter is the selectivity in conversion of NO with respect to ammonia, being always present as a side reaction of ammonia combustion, the minimization of which is a key factor for both process economics and NO efficiency. Related to this aspect, another important parameter is the efficiency of reduction of NO when the ammonia present is less than the stoichiometric value. 

Ethanolamines became available commercially in the early 1930s they assumed steadily growing commercial importance as intermediates after 1945, because of the large-scale production of ethylene oxide. Since the mid-1970s, economical production of very pure, colourless ethanolamines has been possible. Ethanolamines are produced on an industrial scale exclusively by reaction of ethylene oxide (see lARC, 1994) with excess ammonia. This reaction takes place slowly but is accelerated by water. An... 

Borazine, B3N3H6, was first prepared by thermolysis of the diborane ammonia adduct [(BH2)(NH3)2] [BH4] . More convenient procedures for the laboratory preparation of this important ring system in multigram quantities involve either (a) the decomposition of ammonia- borane [eqn (9.1)] or (b) the reaction between ammonium sulfate and sodium borohydride [eqn (9.2)]. The latter method provides a convenient and economical synthesis of borazine. 

The most important industrial alkalis are the weak alkali ammonia (Section 9.3), caustic soda (sodium hydroxide), and lime (calcium oxide).1-6 For many industrial and agricultural purposes, the most economical source of alkali is lime, which is used in steelmaking and other metallurgical operations ( 45% of U.S. production of lime), in control of air pollution from smokestack gases (Chapter 8), in water and sewage treatment (Sections 9.6 and 14.5), in pulp and paper production (Section 10.4), in reduction of soil acidity, in cement and concrete manufacture (indirectly, as discussed later), and in many chemical processes such as paper making (Section 10.4). In short, lime is one of the most important of all chemical commodities. 

Finally, one of the first continuous ion-exchange plants installed used a weak-acid resin to recover copper from rayon-fibre spinning solutions. In the Bemberg or copper(II) ammonium process,357 the spinning takes place in an addic copper sulfate solution, and the fibre is then washed in ammonia solution. The wash water contains as much as 30% of the copper required for the spinning operation and its recovery is important in economic and environmental terms. The copper is extracted as the cationic amine complex by the weak-acid resin, and is then stripped from the resin with the acidic spinning solution. Zinc is recovered in a similar manner from vicrose rayon-spinning operations. 

Some most important solvent-free routes for selective oxidations of hydrocarbons and aromatics [9], hydrogenations [10], and for a one step production of e-caprolactam from cyclohexanone with a mixture of air and ammonia using porous heterogeneous catalysts have been reported, in which the active sites have been atomically engineered [11]. There are also reactions in which at least one reactant is liquid under the conditions employed, which means the solvent normally used can simply be left out. To begin with, two industrially important examples are discussed, which confirm that a reaction process that is more environmentally friendly can also be economically very acceptable. This is followed by some recent examples of solvent-free reactions covering a remarkably broad range of reaction types in which the term solvent-free refers solely to the reaction itself. On the other hand, workup processes, except for a few examples, invariably involve the use of solvent. The... 

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. 

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