Combustion of ammonia

C15-0098. The first step in the Ostwald process for the synthesis of nitric acid is the combustion of ammonia ... 

A final relevant parameter is the temperature window in which the conversion of NO is at the maximum value. In fact, due to the presence of the side combustion of ammonia, the conversion of NO typically decreases at temperatures above the maximum. The presence of a sharp or broader maximum is related to the rate of reaction of ammonia... 

For example, the combustion of ammonia in oxygen produces nitrogen dioxide and water. 

Q O The combustion of ammonia in oxygen to form nitrogen dioxide and water vapour involves covalent molecules in the gas phase. The oxidation number method for balancing the equation was shown in an example in this section. Devise a half-reaction method for balancing the equation. Describe the assumptions you made in order to balance the equation. Also, describe why these assumptions did not affect the final result. 

The relative number of reacting and resulting molecules are indicated by the coefficients associated with the molecules. For example, the combustion of ammonia in oxygen is described by the balanced chemical equation... 

The yield of nitric oxide in Eq. (9.7) depends on pressure and temperature as indicated in Table 9.497. The formation of nitrogen by direct combustion of ammonia [see Eq. (9.7)] usually represents the most significant yield loss. Small amounts of nitrous oxide (N20) are also formed, but much lower reaction temperatures (around 500 °C) are required for N20 to become a significant yield loss104. 

Preparation ofnitrosylsulfuric acid from nitrous gases obtained from combustion of ammonia and sulfuric acid ... 

Nitrogen monoxide, NO, is one of the gases that is responsible for smog. It is produced in various ways, one of which is during the combustion of ammonia. 

The ozonization of air by moist phosphorus is said to produce ammonium nitrate,6 and it is also formed by the combustion of ammonia in oxygen, and by that of hydrogen in nitric acid.6 When ozone reacts with liquid ammonia cooled with ether and liquid carbon dioxide, the product consists of ammonium nitrate containing 2 per cent, of ammonium nitrite.7... 

Nitrogen(II) oxide in 80 to 90% yield is produced by the catalytic combustion of ammonia in oxygen in the presence of water vapor on a platinum-rhodium catalyst ... 

The acid is degassed by blowing out with secondary air and distilled (the head product consisting of highly concentrated acid and the sump product of the azeotropic acid). The azeotropic acid is recycled. The concentration of nitrous gas in the tail gas is <100 ppm. In the Sabar process the manufacture of low or medium concentration acid is possible in addition to highly concentrated acid. These are obtained by adding acid condensate from the combustion of ammonia to the sump of the nitric acid tower. 

Although the process configuration varies widely there are three main steps common to each, they are oxidation of ammonia to nitric oxide (NO), oxidation of NO to nitrogen dioxide (N02), and then absorption of N02 in water to produce nitric acid (Figure 3.11). The first step of the catalytic combustion of ammonia takes place over a catalyst consisting of platinum/rhodium (90 10) or platinum/rhodium/palladium (90 5 5). The reaction is very rapid and goes almost to completion as shown in Reaction 3.11. The reaction is one of the most efficient catalytic processes in industrial chemistry, having an extremely... 

In conventional processes (Stamicarbon and Inventa), hydroxylamine sulfate is prepared by the Raschig technique. The first reaction is the catalytic combustion of ammonia in air at 850°C. in the presence of a platinum foam catalyst The heat generated by the reaction is recovered in a boiler which produces steam. Nitrogen oxides are formed by the following reaction mechanism ... 

From Table 15.9-2, the heat of combustion of ammonia is 383.0 kJ/mol, that of glucose is 467.8 kJ/C-mole, and ethanol is 684.5 kJ/mol. The heat of combustion of the biomass is unknown, so the energy regularity method will be used ... 

H. N. Warren, some nitride as well 0. Schmidt studied the adsorption of nitrogen by chromic oxide, and also of ammonia. J. E. Ashby found that heated chromic oxide favours the combustion of ammonia in air. D. Maneghini studied it as a catalyst in the oxidation of ammonia. F. Ephraim observed that chromic oxide is attacked by SOdium amide. M. Z. Jovitschitsch found that chromic oxide dissolves when digested for 10 hrs. with fuming or cone, nitric acid the calcined oxide does not dissolve in nitric acid R. Weber found that if strongly heated with phosphorus pentachloride chromic oxide furnishes the chloride. C. Lefevre studied the action of alkali arsenates on chromic oxide. 

Combustion of ammonia to form nitrous gases (Ostwald nitric acid process) cold air and ammonia are introduced, with an excess of air such that the heat of reaction is consmned in heating the initial mixture 900°C, Pt/Rh nets. 

For the catalyst based on Mo10V0.33Nb0.nTe0.22Ox, a precise phase composition is claimed, as defined by the ratio of the X-ray diffraction peak intensity at 20 27.3° and 28.2° (CuKa), which minimizes the combustion of ammonia to N2 [29d,j]. 

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