Nitrogen oxide partial pressure

Sulfur dioxide (SO ) and nitrogen oxides (NO ) are oxidized to sulfate and nitrate aerosols either homogeneously rn the gas phase or heterogeneously in atmospheric microdroplets and hydrometeors Gas-phase production of nitric acid appears to be the dominant source of aerosol nitrate because the aqueous phase reactions of NO (aq) are slow at the nitrogen oxide partial pressures typically encountered in the atmosphere (5,i5). Conversely, field studies indicate that the relative importance of homogeneous and heterogeneous SO2 oxidation processes depends on a variety of climatological factors such as relative humidity and the intensity of solar radiation (4, -1 ). 

Ethoxylation, In processing, the fatty acid and catalyst are charged to a reactor and purged with an inert gas such as nitrogen. The partial pressure is adjusted so that the explosive limits of the gas mixture in the reactor during and after addition of ethylene oxide are not exceeded. The mass is heated to reaction temperatures of 115 to 200°C, and ethylene oxide is added until the desired pressure is reached. Heat removal rates control the rate of reaction. Excessive cooling can result in excessive absorption of ethylene oxide into the reaction mixture, which can result in sudden reaction followed by overpressure. The reactor temperature and pressure are controlled until the desired quantity of ethylene oxide has been added. Then the... 

Ethylene oxide storage tanks ate pressurized with inert gas to keep the vapor space in a nonexplosive region and prevent the potential for decomposition of the ethylene oxide vapor. The total pressure that should be maintained in a storage tank increases with Hquid temperature, since the partial pressure of ethylene oxide will also increase. Figure 5 shows the recommended minimum storage pressures for Hquid ethylene oxide under nitrogen or methane blanketing gas. 

It was found that when the partial pressure of nitric oxide was more than 1.5 times greater than the partial pressure of ammonia, the platinum surface remained in a relatively oxidised state and the selectivity to nitrogen was poor. When the partial pressure of nitric oxide was less than 1.5 times the partial pressure of ammonia, the platinum surface remained in a relatively reduced state and the selectivity to nitrogen approached unity. 

The third step in the process involves cooling the reaction gases below their dew point, so that a liquid phase of weak nitric acid is formed. This step effectively promotes the state of oxidation and dimerization (Reactions 3 and 4), and removes water from the gas phase. This in turn increases the partial pressure of the nitrogen peroxide component. 

Y. Kamigaki, Y. Itoh. Thermal oxidation of silicon in various oxygen partial pressures diluted by nitrogen // J.Appl.Phys.- 1977.- V.48, No.7.- P.2891-2896. 

---