Fertilizers synthetic ammonia

Fig. 3. Routes for making synthetic ammonia into fertilizers. The consumption data are for the year ended June 30, 1990 (5). Significant quantities are...

Chemical plants are a series of operations that take raw materials and convert them into desired products, salable by-products, and unwanted wastes. Fats and oils obtained from animals and plants are hydrolyzed (reacted with water) and then reacted with soda ash or sodium hydroxide to make soaps and glycerine. Bromine and iodine are recovered from sea water and salt brines. Nitrogen and hydrogen are reacted together under pressure in the presence of a catalyst to produce ammonia, the basic ingredient used in the production of synthetic fertilizers. 

The single largest use of ammonia is its direct apphcation as fertdizer, and in the manufacture of ammonium fertilizers that have increased world food production dramatically. Such ammonia-based fertilizers are now the primary source of nitrogen in farm soils. Ammonia also is used in the manufacture of nitric acid, synthetic fibers, plastics, explosives and miscellaneous ammonium salts. Liquid ammonia is used as a solvent for many inorganic reactions in non-aqueous phase. Other apphcations include synthesis of amines and imines as a fluid for supercritical fluid extraction and chromatography and as a reference standard in i N-NMR. 

A minor part of mined fossil fuels is used as a raw material for the chemical industry (e.g., plastics, synthetic fabrics, carbon black, ammonia, and fertilizers). The major part supplies the energy needs for modem society. Fossil fuels supply about 86% of global primary energy consumption (39% oil, 24% coal, and 23% natural gas), providing energy for transportation, electricity generation, and industrial, commercial, and residential uses (El A 2001). Coal, and to a lesser extent oil, combustion leaves a significant amount of solid waste. The treatment of solid waste from fossil fuel combustion is treated in different chapters of this book. In this chapter we focus on air emissions of fossil fuel combustion, and their impact on human health and the environment. 

Synthetic fertilizers Fertilizers made from fossil fuels. Examples of synthetic fertilizers are ammonia, ammonium sulfate, and urea. 

Another critical use of nitrogen is in the production of ammonia by the Haber process, named after its inventor, the German chemist Fritz Haber. The Haber process involves the direct synthesis of ammonia from its elements, nitrogen and hydrogen. The two gases are combined at temperatures of 932-1,292°F (500-700°C) under a pressure of several hundred atmospheres over a catalyst such as finely divided nickel. One of the major uses of the ammonia produced by this method is in the production of synthetic fertilizers. 

Three compounds of nitrogen traditionally rank in the top 25 among those chemicals produced in the largest volume in the United States. They are ammonia (number five in 1988), nitric acid (number 12 in 1988), and ammonium nitrate (number 14 in 1988). All three of these compounds are extensively used in agriculture as synthetic fertilizers. More than 80% of the ammonia produced, for example, goes to the production of synthetic fertilizers. 

By far the most notable use of nitrogen is in the production of ammonia (NH3). Ammonia is used to make other compounds, such as ammonium sulfate ((NH4)2S04), ammonium nitrate (NH4NO3), urea (C0(NH2)2)> and nitric acid (HNO3). These compounds are used primarily to make synthetic fertilizers. Both elemental nitrogen and nitrogen compounds have a number of important industrial uses. 

Ammonia is an important primary inorganic material. 85% of the worldwide production is utilized in the manufacture of synthetic fertilizers. Ammonia production therefore represents an indicator of the size of the fertilizer industry in a particular country. 

Ammonia is the source of nitrogen in many fertilizers. Unfortunately, nature does not produce NH3 and related plant nutrient compounds rapidly enough to provide an adequate food supply for the world s growing population. Commercial synthetic fertilizers have helped to lessen this problem, but at great cost for the energy that is required to produce them. 

The largest and most significant use of ammonia and ammonium compounds is the agricultural application of fertilizers. Ammonia and ammonium compounds used as fertilizer represent 89% of the commercially produced ammonia, with plastics, synthetic fibers and resins, explosives, and other uses accounting for most of the remainder (Kramer 2002). Direct uses of ammonia as fertilizer can be broken down into the following categories anhydrous ammonia, 30% urea/ammonium nitrate solutions, 24% urea, 17.5% ammonium nitrate, 5% ammonium sulfate, 2% other forms, 2.5% and multiple nutrient forms, 19% (Kramer 2000). Most ammonium compounds and nitric acid, which are produced from anhydrous ammonia, are used directly in the production of fertilizers. 

Ammonia Ammonia (NH3) is produced both in natural ecosystems and by anthropogenic sources, such as agricultural industries, synthetic fertilizers, and burning of biomass. It is the only common atmospheric gas that is a base and is highly soluble in water. 

Synthetic fertilizers (Fritz Haber) Haber also invents the Haber process to synthesize ammonia on a small scale. 

Sustainably generated hydrogen has many uses in chemical synthesis and in synthetic fuels manufacture. In addition to its applications in fuel cells, it can be burned directly in gas turbines and internal combustion engines. It is the fuel of choice for fuel cells and, combined chanically with N2 from air, it is used to make ammonia for fertilizer and synthetic nitrogen compounds. It is a key feedstock for processes to convert biomass materials, such as sugars, to useful synthetic chemicals. And elemental H2 is a key ingredient in making synthetic fnels from coal, biomass, and even CO2. 

The synthesis of ammonia from its elements ranks as one of the most important discoveries in the history of the science of catalysis, not only because of its industrial application in which synthetic fertilizers have contributed enormously to the survival of mankind, but also from the viewpoint of fundamental science. Even today, some eighty years after the first demonstration of ammonia synthesis, many original scientific papers on the mechanism of the catalytic synthesis of ammonia are still published. Every time a new method, technique, or concept has appeared in the field of heterogeneous catalysis, it has been applied to this reaction. Specific examples of these applications over the years include the concepts of gas equilibrium, activated adsorption, structure sensitivitystoichiometric number and kinetic studies, " nonuniform surfaces, the measurements of surface area, surface composition and promoter distributions, and the use of isotopic and spectroscopic techniques. In particular, various surface science techniques have been applied successfully to this reaction system over well-defined single crystal surfaces in recent years. In this way the effect of promoters on the iron catalyst has been elucidated. Accordingly, the history of ammonia synthesis parallels not only that of industrial catalysis, but also the development of the science of catalysis. 

Figure 1.1(a) shows four of the five practically-identical ammonia synthesis plants at the Donaldsonville, LA plant of CF Industries. Each of these produces 1500 tons/day of ammonia, for use in fertilizer. These five plants produce a total of about 5 billion pounds per year of ammonia, equivalent to 16 pounds per year for each person in the United States. That fertilizer contributes in a major way to the abundance, variety, and low cost of food in the United States. Such plants are vitally important to the human race. They produce the fixed nitrogen used in fertilizers throughout the world. Roughly 80 pounds of a variety of fertilizers are produced per year for each person on earth. If we lost this supply of synthetic fertilizers and then all stopped eating meat, we would be able to feed about 80% of the world s... 

All of these realities will be taken up in considerable detail in this book. I will first describe nitrogen s unique and indispensable status in the biosphere, its role in crop production, and the traditional means of supplying the nutrient. Then I will concentrate on various attempts to expand natural nitrogen flows by introduction of mineral and synthetic fertilizers. The core of the book is a detailed narrative of the epochal discovery of ammonia synthesis by Fritz Haber and its commercialization by Carl Bosch and BASF. 

Nearly all commercial nitrogen fertilizer is derived from synthetic ammonia. However, prior to the introduction of ammonia synthesis processes in the early 1900s dependence was entirely on other sources. These sources are stdl utilized, but their relative importance has diminished. 

Over 95% of all commercial nitrogen fertilizer in the 1990s is derived from synthetic ammonia (qv). Worldwide, the yearly production of synthetic ammonia is about 120 million t, of which about 85% finds use in fertilizers. 

The principal routes by which synthetic ammonia is processed into finished fertilizers are shown in Figure 3. Also included are U.S. consumption data on each of these products for the crop year ended June 30, 1990. 

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