Environmental concerns nitric oxide

Industry, in fact, has a major interest in these diesters as building blocks for nylon 6,6 and nylon 7,7 in the production of polyesters and polyamides. However, their present synthesis raises an environmental concern. For instance, the oxidation of cyclohexanone by nitric acid (for the preparation of adipic acid), accounts for more than 10% of the total yearly release of N2O, which is among the main gases responsible for the greenhouse effect. The reaction of Scheme 4.14 represents an eco-friendly alternative synthesis of a,(i)-diesters which uses green reagents and, relevantly, has a 100% atom economy. The overall process is mechanistically described as a retro-Claisen condensation. 

Humanity s major sources of energy are derived from fossil fuels, principally oil, gas, coal, and wood. The major combustion by-products of fossil fuel burning include sulfur dioxide (SO2), carbon dioxide (CO2), and nitric oxide (NO2), and partially oxidized hydrocarbons. The process of burning fossil fuels in thermal power plants, factories, homes, and motor vehicles emits enormous amounts of the aforementioned pollutants. The most important environmental concerns resulting from fossil fuel use are global climate change, acid rain, surface ozone, and partic-ulate-Zaerosol-bound toxins. 

The maj or environmental concern for nitric acid oxidation of either cyclohexanol or the KA Oil is the emission of the greenhouse gas nitrous oxide, N2O. Theemission factor is estimated to be around 300 kg of N2O per ton of AA indeed, the real value is between 260 and 330 (around 0.75-1.2 mol of N2O per mole of AA), depending on the amount of catalyst used and the KA Oil composition. For a global AA production of 3.0 M-tonyr, the total amount of N2O produced is estimated to be about 0.9 M-tonyr. However, nowadays less than 5% of total emission of N2O into the atmosphere is from anthropogenic origin, and of this 5% only a small fraction is due to AA production, because almost all the AA producers have installed N2O decomposition units. 

The interaction of nitric oxide (NO) with metal ions in zeolites has been one of the major subjects in catalysis and environmental science and the first topic was concerned with NO adsorbed on zeolites. NO is an odd-electron molecule with one unpaired electron and can be used here as a paramagnetic probe to characterize the catalytic activity. In the first topic focus was on a mono NO-Na" complex formed in a Na -LTA type zeolite. The experimental ESR spectrum was characterized by a large -tensor anisotropy. By means of multi-frequency ESR spectroscopies the g tensor components could be well resolved. The N and Na hyperfine tensor components were accurately evaluated by ENDOR spectroscopy. Based on these experimentally obtained ESR parameters the electronic and geometrical structures of the NO-Na complex were discussed. In addition to the mono NO-Na complex the triplet state (NO)2 bi-radical is formed in the zeolite and dominates the ESR spectrum at higher NO concentration. The structure of the bi-radicai was discussed based on the ESR parameters derived from the X- and Q-band spectra. Furthermore the dynamical ESR studies on nitrogen dioxides (NO2) on various zeolites were briefly presented. 

H2S and HCl, which clearly is of environmental concern throughout the world. These potential gaseous pollutants can be converted electro-chemically, in the liquid state, to species which are more environmentally acceptable and which may have some commercial value. Sulphur dioxide can be oxidised to sulphuric acid or reduced to sulphur, chlorine can be reduced to chloride ions, hydrogen sulphide can be oxidised to sulphur and nitrous oxides can be oxidised to nitric acid. 

It is nearly 40 years since the first catalytic devices were commercially produced and fitted into cars, after the recognition that car exhaust primary pollutants, that is, unburned hydrocarbons (HCs), nitrogen oxides (NO ), and carbon monoxide (CO), interact with sun light resulting in the formation of secondary pollutants (e.g., ozone, oxygenated hydrocarbons and hydrocarbon radicals, peroxyacetyl nitrate PAN, and nitric dioxide), which are responsible for the photochemical smog in capital cities [1]. The phenomenon had become of such a concern in almost all the big cities, that forced environmental legislation firstly introduced in 1970 by the US Clean Air Act (US-CAA), and practically applied in 1975 [2]. 

---