NOX oxidation

NOx - Oxides of nitrogen (principally NO and NO2) are formed in combustion processes and as a byproduct of chemicals production. 

Besides NOx oxides, there is nitrous oxide (N2O), which is of special interest in isotope geochemistry. N2O is present in air at around 300 ppb and increases by about 0.2% per year. Nitrous oxide is an important greenhouse gas that is, on a molecular basis, a much more effective contributor to global warming than CO2 and that is also a major chemical control on stratospheric ozone budgets. 

TABLE 9.22 Major Products Identified in the Particles Formed from the VOC —NOx Oxidations in... 

The yields of secondary organic aerosols from a series of aromatic hydrocarbon-NOx oxidations have been measured by Odum et al. (1997a, 1997b). They showed that the total secondary organic aerosol formed from a mixture of aromatic hydrocarbons can be approximated as the sum of the individual contributions. Based on their experiments, the yield of secondary organic aerosols expressed as the total organic particle mass concentrations formed, AM, (in fxg m 3), divided by the mass concentration of aromatic precursor reacted, A (aromatic), is given by... 

Figure 9.53, for example, shows a plot of the yield of secondary organic aerosol from the VOC-NOx oxidation in air of some aromatic compounds as a function... 

Figure 16.39 shows a similar relationship measured at a site downwind of metropolitan Toronto, Canada (Roussel et al., 1996). The slope of this line gives 13.8 ppb of 03 formed per ppb of NOx oxidized. The... 

NOx Oxides of nitrogen—exhaust emission created from reactions of nitrogen in the air with oxygen at peak combustion temperatures. 

Oxidation of Dissolved S02 in Atmospheric Droplets Free Radical, Polar and Photoassisted Pathways, in J. G. Calvert, Ed., Acid Precipitation S02, NO, NOx Oxidation Mechanisms Atmospheric Considerations, Butterworth, Boston-London, pp. 101-172. 

As Spark retard is employed to raise the temperature, the concentrations of oxygen and the three legislated exhaust emission gases HC (hydrocarbons), CO (carbon monoxide), and NOx (Oxides of nitrogen) which get to the catalyst face at stoich, are reduced. The HC concentration during events 2 and 3 of the cycle is also reduced. 

There are mainly two proposed mechanisms for NOx contamination recovery NO reduction and NOx oxidation. Mohtadi et al. [35] proposed a NOx reduction mechanism [35] ... 

Since only a few groups have studied NOx contamination mechanisms, there is as yet no consensus about these processes. Thus far, two primary mechanisms for NOx contamination have been proposed the NOx reduction mechanism and the NOx oxidation mechanism. Mohtadi et al. [11] proposed the reduction mechanism, suggesting that NO2 was electrochemically reduced and thereby competed with O2 for Pt sites. The product of NO2 reduction was NH4+ (via equation (3.8)). NH4+ has been reported to be an ionomer poisoning species that might affect the ionomer and/or catalyst-ionomer interface. 

The major atmospheric pollutants are SO2, H2S, NOx (oxides of nitrogen), CO2, dust particles and marine salts. The sources of the contaminants are shown in Table 10.3. 

One of a few experimental studies on the promoting effect of NOx oxidation of hydrocarbons at pressures much higher than atmospheric was performed in [195]. The oxidation of very rich (with a fuel equivalence ratio of 116 > > 99), stoichiometric (4> = 1), and very... 

Experimental Conditions, molecular packing density, F, from C signal was employed to calculate nox (oxidation factor) other conditions as in Table 1. 

Acid rain is precipitation polluted by acidification with atmospheric pollutants. These pollutants include emissions of oxides of nitrogen (NOx), oxides of sulfur (SOx), and hydrogen chloride radicals. Various strengths of nitric acid, sulfuric acid, and hydrochloric acid result. Key indicators of acid rain include emission levels of NOx and SOx, wet sulfate deposits, and trends in acidity in lakes and other freshwater bodies. An increase in emissions that increases the level of any of these indicators will bring environmental, r atory, and potentially public and special-interest group pressures to bear on a plant. Sample measurements of these indicators on a national or provincial scale arc illustrated in Figs. A-4 to A-7. 

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