Nitrogen oxides chemistry

Nitrogen-containing compounds, particularly oxidized nitrogen compounds, play a central role in the chemistry of the troposphere. So-called active nitrogen, denoted NO, the sum of NO and N02, exerts a controlling influence on the abundance of the OH radical and is essential for the photochemical production of tropospheric ozone. 

Logan (1983) has estimated the global inventory of NO emissions (emission rates expressed in units of 1012 g N yr-1, with mean value given and range of estimates in parentheses)  

The emissions of NO from fossil fuel combustion and biomass burning are increasing. Recent simulations show that these anthropogenic sources of NO may have contributed to increases in NO concentration over vast 

Total odd nitrogen, denoted NOy, is the sum of NO, HN03, H02N02, HONO, N03, 2N205, organic nitrates, and possibly other inorganic nitrates and particulate nitrate, NO. Ambient measurements of oxidized nitrogen compounds have been surveyed by Fehsenfeld et al. (1988) and Ridley (1991). 

The oxides of nitrogen emitted into the atmosphere comprise NO, N02, N20, HONO, and, possibly, HN03. N20 is chemically inert in the troposphere, being transported into the stratosphere where it photodisso-ciates (Liu et al., 1977). 

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Sites of Receptor Location 128 4.1 Nitrogen Oxide Chemistry in the ... 

Although we wish to preserve the ozone in the stratosphere, we want to minimize its production in the troposphere, that part of the atmosphere where we live. Photochemical smog produced as a result of the action of solar radiation on the effluents from automobiles is the primary source of ozone in the troposphere. The trigger for photochemical smog is based on nitrogen oxide chemistry, so we defer our discussion of this problem until Chapter 16 on Group 5A chemistry. 

Agnew S F, Swanson B I, Jones L FI, Mills R L and Sohiferl D 1983 Chemistry of nitrogen oxide (N2O4) at high pressure observation of a reversible transformation between moleoular and ionio orystalline forms J. Phys. Chem. 

Pollution control such as the reduction of nitrogen oxides, halocarbons and hydrocarbons from flue gases [37] is another important field of plasma-assisted chemistry using non-thennal plasmas. The efficiency of plasma chemical reactions can be enhanced by introducing catalysts into the plasma [38, 39]. 

At high flame temperatures, small amounts of nitrogen react with oxygen to form nitrogen oxides, NO, primarily nitric oxide, NO. The chemistry of these nitrogen oxides is complex. Ultimately, however, some form nitrosylsulfuric acid, which ends up either as trace amounts in product acids or, in considerably higher concentrations, as condensed acid collected at mist eliminators. 

Gas-phase oxidation of thiols has been discussed in some depth (33). This review mainly emphasi2es atmospheric processes, but a section on nitrogen oxides and thiols appears to be broadly appHcable. The atmospheric oxidation chemistry of thiols is quite different from that of alcohols. 

Synthetic and structural chemistry of heme derivatives with nitrogen oxide ligands 99ACR350. 

Nitrogen forms several oxides, with oxidation numbers ranging from - -l to +5. All nitrogen oxides are acidic oxides and some are the acid anhydrides of the nitrogen oxoacids (Table 15.2). In atmospheric chemistry, where the oxides play an important two-edged role in both maintaining and polluting the atmosphere, the) are referred to collectively as NO (read nox ). 

Nitrogen oxides also play a significant role in regulating the chemistry of the stratosphere. In the stratosphere, ozone is formed by the same reaction as in the troposphere, the reaction of O2 with an oxygen atom. However, since the concentration of O atoms in the stratosphere is much higher (O is produced from photolysis of O2 at wavelengths less than 242 nm), the concentration of O3 in the stratosphere is much higher. 

Major unknowns in the mechanism by which a hydrocarbon fuel bums concern the pyrosynthesis reactions that lead to the formation of polycyclic aromatic hydrocarbons (PAHs) and soot and the oxidation chemistry of atoms other than carbon and hydrogen (heteroatoms) in the fuel, particularly nitrogen, sulfur, and halogens. 

Smog contains nitrogen oxides, ozone, and iarger moiecuies. The chemistry of smog is compiex and not fully understood. Atmospheric scientists are studying how smog forms and how it can be prevented. 

Lunsford, J.H. (1975) The Catalytic Chemistry of Nitrogen Oxides. Plenum, New York. 

Less, but still significant, information is available on the surface chemistry of other nitrogen oxides. In terms of N20, that molecule has been shown to be quite reactive on most metals on Rh(110), for instance, it decomposes between 60 and 190 K, and results in N2 desorption [18]. N02 is also fairly reactive, but tends to convert into a mixed layer of adsorbed NO and atomic oxygen [19] on Pd(lll), this happens at 180 K, and is partially inhibited at high coverages. Ultimately, though the chemistry of the catalytic reduction of nitrogen oxide emissions is in most cases controlled by the conversion of NO. 

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