Nitric acid manufacture absorber

Industrial. Nitric acid is itself the starting material for ammonium nitrate, nitroglycerin [55-63-0] trinitrotoluene [118-96-7]., nitroceUulose [9004-70-0] and other nitrogen compounds used in the manufacture of explosives (see Explosives and propellants). Nitric acid is made by oxidation of ammonia to nitrogen dioxide [10102-44-0] which is subsequently absorbed by water. 

Ammonium nitrate is manufactured by reacting ammonia with nitric acid. Consider the process shown by Fig. 9.19. First, namral gas is reformed and converted into hydrogen, nitrogen and carbon dioxide. Hydrogen and nitrogen are separated an fed to the ammonia synthesis plant. A fraction of the produced ammonia is employed in nitric acid formation. Ammonia is first oxidized with compressed air then absorbed in water to form nitric acid. Finally nitric acid is reacted with anunonia to oduce ammonium nitrate. 

Platinum also is used extensively as a catalyst in hydrogenation, dehydrogenation, oxidation, isomerization, carbonylation, and hydrocracking. Also, it is used in organic synthesis and petroleum refining. Like palladium, platinum also exhibits remarkable abdity to absorb hydrogen. An important application of platinum is in the catalytic oxidation of ammonia in Ostwald s process in the manufacture of nitric acid. Platinum is installed in the catalytic converters in automobile engines for pollution control. 

Some nitric acid is used for the manufacture of explosives and chemicals, but much is converted on-site to the potentially explosive high nitrogen fertilizer ammonium nitrate (Section 2.11). Ammonia gas from the Haber plant is absorbed in aqueous HN03, and the NH4N03 solution is evaporated to a liquid melt (< 8% H20) for crystallization, but care must be taken to keep the pH of the solution above about 4.5 and to exclude any material (chlorides, organic compounds, metals) that might catalyze the explosive decomposition of NH4N03. It is also wise to keep the melt mass low and to vent it to avoid pressure buildup. The solid product should be stored well away from the main plant. 

Nitric acid is now manufactured by combusting ammonia in air in the presence of a (platinum or other noble metal) catalyst, and the nitrogen oxides thus formed are oxidized further and absorbed in water to form nitric acid. 

The first reaction is run over platinum-rhodium catalysts at around 900°C (1,652°F). In the second and third stages, a mixture of nitric oxide and air circulates through condensers, where it is partially oxidized. The nitrogen dioxide is absorbed in a tower, and nitric acid sinks to the bottom. Nitric acid is mainly used to make ammonium nitrate, most of it for fertilizer although it also goes into the production of explosives. Nitration is used to manufacture explosives such as nitroglycerine and trinitrotoluene (TNT) as well as many important chemical intermediates used in the pharmaceutical and dyestuff industries. 

In the manufacture of nitric acid, ammonia and preheated air are mixed to form a gas containing 10.0 mole% NH3 at 600 C. The ammonia is then catalytically oxidized to form NO2, which is absorbed in water to form HNO3. If ammonia enters the gas blending unit at 25 C at a rate of 520 kg/h and heat is lost from the mixer to its surroundings at a rate of 7.00 kW, determine the temperature to which the air must be preheated. (See Example 8.3-6.)... 

The object to be attained in the commercial manufacture is the maximum yield of tetranitromethane calculated on the weight of nitric-acid and the volume of acetylene used should be absorbed. 

Toxiooioor,—The brown fumes given off during many processes, in which nitric acid is decomposed, are dangerous to life. All such opera tions, when carried on on a smidl scale, as in the laboratory, should be conducted under a hood or some other arrangement, by which the fumes are carried into the open air. When, in industrial processes, the volume of gas formed becomes such as to be a nuisance when discharged into the air, it should be utilized in the manufacture of H,SO or absorbed by H,0 or an alkaline solution. 

Nitric acid is an important industrial chemical and is manufactured on a large scale in the Haber-Bosch process closely tied to NH3 production the first step is the oxidation of NH3 to NO (equation 14.21). After cooling, NO is mixed with air and absorbed in a countercurrent of water. The reactions involved are summarized in scheme 14.109 this produces HNO3 in a concentration of a 60% by weight and it can be concentrated to 68 %> by distillation. 

Sulfuric acid is used in the laboratory to dry gases (except ammonia), to prepare nitric acid and ethene, and to absorb alkenes. In industry, it is used to manufacture fertilizers (e.g. ammonium sulfate), rayon, and detergents, to clean metals, and in vehicle batteries. 

Nitrogen compounds must be absorbed in several chemical and related processes, the most important of which is the absorption of nitrogen peroxide in water for the manufacture of nitric acid. Absorption of nitrous gases also takes place in the lead-chamber process used for the production of sulfuric acid, in the metallurgical industries where metals are treated with nitric acid, and in the purification of several tail gases. 

Prepare a stock solution of 0.01 M silver nitrate, acidified to pH5-6. Using a very dilute nitric acid solution (pH5), prepare a series of solutions from the stock solution in die range 10 -5 x 10 M. Measure the absorbance of each solution at 328.1 nm in an atomic absorption spectrometer using an air/acetylene flame (flow ratio 8.0 and 3.1 dm min respectively) using the slit setting and burner height recommended by the manufacturer. Plot absorbance against concentration and use the calibration plot for [Ag(I)] determination of any dilute silver solution. 

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