Manufacturing processes, ammonia

Improvements in ammonia manufacturing processes have reduced operating pressures. In the 1930s ammonia plants operated at pressures as high as 600 bar. In the 1950s, process... 

All ammonia manufacturing processes are based on the synthesis of ammonia from nitrogen and hydrogen. Thus the many processes are differentiated, among other factors, by the method of producing the hydrogen and nitrogen for the synthesis. 

Carbon dioxide is used in the manufacture of sodium carbonate by the ammonia-soda process, urea, salicyclic acid (for aspirin), fire extinguishers and aerated water. Lesser amounts are used to transfer heat generated by an atomic reactor to water and so produce steam and electric power, whilst solid carbon dioxide is used as a refrigerant, a mixture of solid carbon dioxide and alcohol providing a good low-temperature bath (195 K) in which reactions can be carried out in the laboratory. 

In one manufacturing process, aluminum chloride is treated with a solution containing sodium carbonate and sodium bicarbonate. The product of this reaction is mixed with the precipitate obtained by reaction of a solution of aluminum chloride and ammonia. The mixed magma is dialyzed, the product mixed with glycerol (qv), sodium benzoate is added, and the mixture is then passed through a coUoid mill. 

Ammonia is used in the fibers and plastic industry as the source of nitrogen for the production of caprolactam, the monomer for nylon 6. Oxidation of propylene with ammonia gives acrylonitrile (qv), used for the manufacture of acryHc fibers, resins, and elastomers. Hexamethylenetetramine (HMTA), produced from ammonia and formaldehyde, is used in the manufacture of phenoHc thermosetting resins (see Phenolic resins). Toluene 2,4-cHisocyanate (TDI), employed in the production of polyurethane foam, indirectly consumes ammonia because nitric acid is a raw material in the TDI manufacturing process (see Amines Isocyanates). Urea, which is produced from ammonia, is used in the manufacture of urea—formaldehyde synthetic resins (see Amino resins). Melamine is produced by polymerization of dicyanodiamine and high pressure, high temperature pyrolysis of urea, both in the presence of ammonia (see Cyanamides). 

Sodium bicarbonate precipitates from solution and is recovered by filtration. Ammonium chloride is then crystallised from the filtrate, separated, washed, and dried. The exact proportion of ammonium chloride recovered depends on the relative demands for sodium carbonate and ammonium chloride. If economic conditions requite, part of the ammonia can be recovered and returned to the hrine-ammoniation step by distillation of the ammonium chloride solution ia the presence of lime. The spent calcium chloride Hquor, a final product ia manufacture of sodium carbonate by the ammonia—soda process, can also be used to obtain ammonium chloride. This Hquor is treated with ammonia and carbon dioxide... 

Manufacture. Historically, ammonium nitrate was manufactured by a double decomposition method using sodium nitrate and either ammonium sulfate or ammonium chloride. Modem commercial processes, however, rely almost exclusively on the neutralization of nitric acid (qv), produced from ammonia through catalyzed oxidation, with ammonia. Manufacturers commonly use onsite ammonia although some ammonium nitrate is made from purchased ammonia. SoHd product used as fertilizer has been the predominant form produced. However, sale of ammonium nitrate as a component in urea—ammonium nitrate Hquid fertilizer has grown to where about half the ammonium nitrate produced is actually marketed as a solution. 

Research in catalysts for ammonia manufacture is stiU going on, and though the use of supported metals such as mthenium may be two to three times as active as promoted iron oxide, catalysts 50—100 times more active than promoted iron oxide are required to affect process economics significantly. 

Ammonia oxidation Test drawn during manufacturing process to evaluate the ammonia oxidation rate for the nitrifiers. 

Eng 20, 470-477 (1919) (Description of ammonia oxidation process beginning with Kuhl-mann s method of 1839 and ending with the cyanamide process at Muscle Shoals) 7) C.L. Parsons, 1EC 11,541 (1919) (Oxidation of ammonia to nitric acid as well as the prepn of nitric acid from Chile saltpeter) 8) F.C. Zeis-berg, ChemMetEng 24, 443-45 (1921) (Manuf of nitric acid from Chilean saltpeter brief description) 9) G.B. Taylor, IEC 26,1217-19 (1922) (Some economic aspects of ammonia oxidation) 10) Ministry of Munitions, Manufacture of Nitric Acid from Nitre and Sulfuric Acid , London (1922) (Book No 7 of Technical Records of Explosives Supply, 1915—1919)... 

FIGURE 9.17 The Haber process is still used to produce almost all the ammonia manufactured in the world. This pie chart shows how the ammonia is used. The figures are percentages. Note that 80%— as shown by the green band—is used as fertilizer, either directly or after conversion into another compound. 

The Haber process for ammonia manufacture, which operates above the critical point of ammonia. 

Bosch also helped develop Haber s process into an industrial process. In 1913, Haber and Bosch opened an ammonia manufacturing plant in Germany. A year later, World War I started. Saltpeter had another use besides making fertilizer. It was also necessary to make nitric acid that was used to make explosives. When the war started, the British Navy quickly cut off Germany s supply of Chilean saltpeter. If not for the Haber process, some historians estimate that Germany would have run out of nitrates to make explosives by 1916. The war lasted another two years, however, because Germany did not need to rely on outside sources of nitrates for fertilizers or explosives. 

Control of exudation depends mainly on the suitable choice of the nitrocellulose used. Some lack of uniformity in this product is certainly desirable. This offers no serious difficulty, although it is necessary to ensure a constant watch on manufacturing processes to see that quality is maintained. In other gelatine explosives, particularly those containing ammonium nitrate, exudation can be induced by slow chemical reaction. The addition of alkalis, for example, can liberate ammonia which in turn can react with nitrocellulose and cause it to lose its power of binding nitroglycerine. Such effects are accelerated at high temperatures and under wet conditions and it is usual practice to test all explosives under such adverse conditions before they are put on the market. 

The SMR is by far the most important and widely used process for the industrial manufacture of hydrogen, amounting to about 40% of the total world production [7]. The technology is well developed and commercially available at a wide capacity range, from <1 t/h H2 for small decentralized units to about 100 t/h H2 for large ammonia manufacturing plants [8]. 

CyAM [Cyanide ammonia] A process for reducing the cyanide concentration in the ammonia liquor from coke manufacture, so that the liquor may be fed to an activated sludge effluent treatment plant. Developed by the United States Steel Corporation and used by that company in two of its coking plants. 

The oxidation of NO to NO2, which is an important step in the manufacture of nitric acid by the ammonia-oxidation process, is an unusual reaction in having an observed third-order rate constant (k o in ( rm) = kso Oc02) which decreases with increase in temperature. Show how the order and sign of temperature dependence could be accounted for by a simple mechanism which involves the formation of (NO)2 in a rapidly established equihbrium, followed by a relatively slow bimolecular reaction of (NO)2 with O2 to form NO2. 

HCN is produced commercially by the reaction of ammonia, methane, and air over a platinum catalyst or from the reaction of ammonia and methane. HCN is also obtained as a by-product in the manufacture of acrylonitrile and may be generated during many other manufacturing processes (Pesce 1994). In 1999, there were 34 companies operating 47 HCN production facilities in... 

Ammonia or its salts are employed in a variety of ways in many trades. From it nitric acid, the vital necessity for the manufacture of all high explosives, can be made it is an essential for the Brunner Mond or Solvay ammonia soda process for the production of alkali in the liquid form it is employed all over the world in refrigerating machinery, but its enormous and increasing use is in agfriculture, where, in the form of sulphate of ammonia, it constitutes one of, if not the most important chemical manures known to man. During the year 1916 350,000 tons of ammonium sulphate were produced in this country, the larger proportion of which was consumed in agriculture—a proportion likely to increase and not diminish if the demand for home production of food continues. 

Ammonia is one of the world s most important chemicals, in terms of the quantity manufactured. Some ammonia is processed into nitric acid and various polymers. Roughly 80% of ammonia is used to make fertilizers, such as ammonium nitrate. In the Haher process for manufacturing ammonia, nitrogen and hydrogen combine in the presence of a catalyst. 

Currently, nitric acid is manufactured exclusively by catalytic oxidation of ammonia. Platinum or platinum-rhodium is an effective catalyst of this oxidation (Ostwald process). Three basic steps in such ammonia oxidation process are (1) oxidation of ammonia to form nitric oxide ... 

Sodium carbonate at present is mostly mined from its natural deposits. It also is manufactured syntheticallly by Solvay (or ammonia-soda) process. The natural production of sodium carbonate currently has supassed its synthetic production. 

Metal Hydride Process for Ammonia Purge Gas, The metal hydride process will be illustrated using the case of hydrogen recovery from an ammonia purge gas stream generated during ammonia manufacture. 

It can hardly be affirmed that the scientific treatment of the ammonia-soda process through recent progress in physical chemistry has given the practical manufacturer any hints on the direction in which he might make his processes more rational and advantageous than before, but there remains the hope that the desired success will be ultimately obtained by a co-operation of theory and practice.—G. Ltjnge (1911). 

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