Nitric oxide from combustion

A substantial portion of fhe gas and vapors emitted to the atmosphere in appreciable quantity from anthropogenic sources tends to be relatively simple in chemical structure carbon dioxide, carbon monoxide, sulfur dioxide, and nitric oxide from combustion processes hydrogen sulfide, ammonia, hydrogen chloride, and hydrogen fluoride from industrial processes. The solvents and gasoline fractions that evaporate are alkanes, alkenes, and aromatics with relatively simple structures. In addition, more complex... 

The OECD project showed that the acidification of precipitation was due to an increased content of sulphuric and nitric acid. The main cause was identified as the increased use of fossil fuels, including motor vehicle traffic. In the atmosphere, sulphur dioxide and nitrogen oxides from combustion processes are oxidized to sulphuric acid and nitric acid, which are taken up and deposited by the precipitation. 

When a reaction resuits in the evolution of heat, it is said to be exothermic (exo- is a prefix meaning "out of") that is, energy flows out of the system. For example, in the combustion of methane, energy flows out of the system as heat. Reactions that absorb energy from the surroundings are said to be endothermic. When the heat flow is into a system, the process is endothermic. For example, the formation of nitric oxide from nitrogen and oxygen is endothermic ... 

Lavoisier and Laplace, on the generation of electricity by evaporation, including also the evolution of hydrogen from iron and dilute sulphuric acid, of carbon dioxide from chalk and dilute sulphuric acid (weak effect), of nitric oxide from iron and dilute nitric acid (very feeble), and the combustion of charcoal. The experiments were really planned by Volta in 1782, who was about when they were done and made himself useful (et nous y etre utile). 

Siebers DL, Caton JA (1990) Removal of nitric oxide from exhaust gas with cyanuric acid. Combust Flame 79(1) 31 6... 

At the high temperatures found in MHD combustors, nitrogen oxides, NO, are formed primarily by gas-phase reactions, rather than from fuel-bound nitrogen. The principal constituent is nitric oxide [10102-43-9] NO, and the amount formed is generally limited by kinetics. Equilibrium values are reached only at very high temperatures. NO decomposes as the gas cools, at a rate which decreases with temperature. If the combustion gas cools too rapidly after the MHD channel the NO has insufficient time to decompose and excessive amounts can be released to the atmosphere. Below about 1800 K there is essentially no thermal decomposition of NO. 

Nitric oxide, NO, results from high-temperature combustion, both in stationary sources such as power plants or industrial plants in the production of process heat and in internal combustion engines in vehicles. The NO is oxidized in the atmosphere, usually rather slowly, or more rapidly if there is ozone present, to nitrogen dioxide, NO2. NO2 also reacts further with other constituents, forming nitrates, which is also in fine parhculate form. 

Nitrogen Dioxide (NO2) Is a major pollutant originating from natural and man-made sources. It has been estimated that a total of about 150 million tons of NOx are emitted to the atmosphere each year, of which about 50% results from man-made sources (21). In urban areas, man-made emissions dominate, producing elevated ambient levels. Worldwide, fossil-fuel combustion accounts for about 75% of man-made NOx emissions, which Is divided equally between stationary sources, such as power plants, and mobile sources. These high temperature combustion processes emit the primary pollutant nitric oxide (NO), which Is subsequently transformed to the secondary pollutant NO2 through photochemical oxidation. 

Note that in addition to the main reaction, the bomb process includes contributions from ignition and all side reactions. These contributions have to be included in the calculation of the energy change associated with the main reaction. Two side reactions normally considered are the combustion of the cotton fuse and the formation of nitric acid from the oxidation of traces of atmospheric N2 that remain inside the bomb even after purging. 

Nitric oxide is the primary nitrogen oxide emitted from most combustion sources. The role of nitrogen dioxide in photochemical smog has already been discussed. Stringent emission regulations have made it necessary to examine all possible sources of NO. The presence of N20 under certain circumstances could, as mentioned, lead to the formation of NO. In the following subsections the reaction mechanisms of the three nitrogen oxides of concern are examined. 

R0kke, N. A., J. E. Hustad, O. K. S0nju, and F. A. Williams. 1992. Scaling of nitric oxide emissions from buoyancy-dominated hydrocarbon turbulent-jet diffusion flames. 24th Symposium (International) on Combustion Proceedings. Pittsburgh, PA The Combustion Institute. 385-93. 

According to [96], electrochemical methods, especially the application of cyclic voltammetry, could be a powerful tool to find suitable catalysts for NO removal from combustion products. Investigation of electrocatalytic properties of vitamin B12 toward oxidation and reduction of nitric oxide was reported in [97]. The catalytic activity of meso-tetraphenyl-porphyrin cobalt for nitric oxide oxidation in methanolic solution and in Nafion film was reported in [98]. 

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