Nitrous oxide reactions atmosphere

Photo-ionization of nitrous oxide in the upper atmosphere only occurs with light of wavelengths shorter than 134 nm, to cause the reaction NO + /7v - NO+ + e-. 

Nitrous oxide (N2O) is an important greenhonse gas with a radiative forcing effect 310 times that of CO2 and a lifetime in the troposphere of approximately 120 years. Part of the N2O is converted to NO in the stratosphere, and so contributes to depletion of ozone. Nitric oxide (NO) is very reactive in the atmosphere and has a lifetime of only 1-10 days. It contribntes to acidification and to reactions leading to the formation of ozone in the troposphere, and so also to global warming. 

Acetic acid is formed when methane reacts with CO or C02 in aqueous solution in the presence of 02 or H202 catalyzed by vanadium complexes.327 A Rh-based FeP04 catalyst applied in a fixed-bed reactor operating at atmospheric pressure at 300-400° C was effective in producing methyl acetate in the presence of nitrous oxide.328 The high dispersion of Rh at sites surrounded by iron sites was suggested to be a key factor for the carbonylation reaction. 

The concentration of nitrous oxide (N2O) in the atmosphere is increasing. This is a concern, since N2O has been identified as a greenhouse gas and as a source of ozoneconsuming NO in the stratosphere. A significant source of N2O to the atmosphere is production of adipic acid (AA), which is used in the production of nylon. Adipic acid is formed from reaction of cyclohexanol with nitric acid (HNO3) according to the scheme in Fig. 13.13. 

The photochemical processes of triatomic molecules have been extensively studied in recent years, particularly those of water, carbon dioxide, nitrous oxide, nitrogen dioxide, ozone, and sulfur dioxide, as they are important minor constituents of the earth s atmosphere. (Probably more than 200 papers on ozone photolysis alone have been published in the last decade.) Carbon dioxide is the major component of the Mars and Venus atmospheres. The primary photofragments produced and their subsequent reactions are well understood for the above-mentioned six triatomic molecules as the photodissociation involves only two bonds to be ruptured and two fragments formed in various electronic states. The photochemical processes of these six molecules are discussed in detail in the following sections. They illustrate how the knowledge of primary products and their subsequent reactions have aided in interpreting the results obtained by the traditional end product analysis and quantum yield measurements. 

Ammonia oxidation was explored at atmospheric pressure, in the temperature range 323-673 K. At these conditions the reaction products were molecular nitrogen, nitrous oxide and water. 

The catalyst samples were prepared by pelletizing mixtures of powdered carbides and inert materials (for instance, BaS04). Oxygen or nitrous oxide were used as oxidants. Experiments were run in a quartz flow reactor at atmospheric pressure at 973-1023 K utilizing 0.2-0.5 g of carbide at flow rate of 30-100 cm3/min. The reactants and reaction products were separated on CaA molecular sieves and l,2,3-tn. v-/ -cyanoethoxypropane/ polysorb A columns. 

Silicon Dioxide. Si02 layers produced by PECVD are useful for intermetal dielectric layers and mechanical or chemical protection and as diffusion masks and gate oxides on compound-semiconductor devices. The films are generally formed by the plasma-enhanced reaction of SiH4 at 200-300 °C with nitrous oxide (N20), but CO, C02, or 02 have also been used (238-241). Other silicon sources including tetramethoxysilane, methyl dimethoxysilane, and tetramethylsilane have also been investigated (202). Diborane or phosphine can be added to the deposition atmosphere to form doped oxide layers. 

Nitrate explosives. The term explosion is applied to the effect produced by a sudden change in the pressure of one or more gases. This may be the result of either chemical or physical changes—that is, the sudden liberation or absorption of gases in chemical reactions or the sudden formation of gases from either liquids or solids. Because certain nitrates decompose readily with liberation of gaseous products, these substances are useful in compounding a variety of commercial explosives. Ammonium nitrate is stable under ordinary atmospheric conditions and may be handled safely in small quantities, even at elevated temperatures. When the dry salt is heated, it decomposes with liberation of nitrous oxide and water,... 

Nitrous oxide is relatively soluble in water (2 x 10 2 M at atmospheric pressure), it reacts very rapidly with eaq( 7 x 109 M 1 s 1) and is practically inert toward OH and H (for the latter, k < 104 M 1 s 1). Because of partial scavenging of e q from the spurs G(OH) in N20-saturated solutions is 6-0. Hydrogen peroxide also converts ejq into OH very efficiently [reaction (6)], but it has... 

An interesting reaction consists in the oxidation of atmospheric nitrogen in air by the agency of platinum black in the presence of potash or baryta water, whereby nitrous acid or ammonium nitrite are produced. ... 

For the major atmospheric oxide of nitrogen—nitrous oxide—the source is biological activity at the surface, and the sink is transport into the stratosphere, where it is destroyed by photodissociation and reaction with 0( D). There are no important photochemical reactions for nitrous oxide in the troposphere. 

You mentioned the reaction between oxygen and nitrous oxide. Most environmental chemists pay attention to NO and NO2 as well as their interconversion, but little attention is paid to N2O. Does N2O have a part in the nitrogen cycle We are very curious about the fact that it is present uniformly in the troposphere at about 0.25 ppm. Is the reaction of oxygen and of direct relevance to the atmosphere ... 

Water is also included in the table to make one point— the solvent that we are all most familiar with is a poor candidate from both engineering and safety standpoint. The critical temperature and pressure are among the highest for common solvents. Ammonia is very unpleasant to work with since a fume hood or other venting precautions are needed to keep it out of the laboratory atmosphere. One of the alternative fluids of potential interest is nitrous oxide. It is attractive since it has molecular weight and critical parameters similar to carbon dioxide, yet has a permanent dipole moment and is a better solvent than carbon dioxide for many solutes. There are evidences of violent explosive reactions of nitrous oxide in contact with oils and fats. For this reason, nitrous oxide should be used with great care and is not suitable as a general purpose extraction fluid. 

Nitrous oxide (N2O) is a long-lived (120 yr) trace component of the atmosphere (Prinn et al., 1990). It is a climate-active gas as it has a radiative forcing 300 times that of CO2, although N2O presently contributes only 5% to the total greenhouse effect (Schimel, 1996). N2O also acts as a source of nitric oxide in the stratosphere and therefore participates in the catalytic removal of ozone (Crutzen, 1970). It is produced as a reaction intermediate in both microbial denitrification and nitrification processes and at greater rates under conditions of low O2 (Law and Owens, 1990) (see Chapter 6.11 by Emerson and Hedges for more details). 

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