Nitrous oxide cooling

Fuel and air or nitrous oxide flow stabilities must be adequate for good precision. Intermediate balast tanks help to smooth out fluctuations caused by compressors.3 As mentioned in Chapter 2, section 5, nitrous oxide cools when it is subjected to a sharp pressure drop, which results in cooling of the cylinder head, and sometimes in instability. The effect is not as important if the nitrous oxide operating pressure... 

How real is the proposed mechanism It turns out that its stages can be modeled separately. In the absence of benzene, decomposition of nitrous oxide in a closed system at temperatures below 300°C leads only to evolution of nitrogen - all of the released o gen under these conditions Is left on the catalyst in the form of alpha-ojqrgen. This process was used as a basis for one of the procedures developed for measurement of alpha-site concentration [9]. When a catalyst loaded Avlth alpha-ojqrgen is isolated fi om nitrous oxide, cooled and reacted with benzene vapors at or below room temperature, phenol is extracted from the catalyst as the only product, thus supporting a model for the second and third steps of the proposed mechanism [10]. 

Nitrous oxide [10024-97-2] M 44.0, h -88.5°. Washed with cone alkaline pyrogallol solution, to remove O2, CO2, and NO2, then dried by passage through columns of P2O5 or Drierite, and collected in a dry trap cooled in liquid N2. Further purified by ffeeze-pump-thaw and distn cycles under vacuum [Ryan and Freeman J Phys Chem 81 1455 1977],... 

Copper metal surface area was determined by nitrous oxide decomposition. A sample of catalyst (0.2 g) was reduced by heating to 563 K under a flow of 10 % H2/N2 (50 cm min"1) at a heating rate of 3 deg.min 1. The catalyst was then held at this temperature for 1 h before the gas flow was switched to helium. After 0.5 h the catalyst was cooled in to 333 K and a flow of 5 %N20/He (50 cm3mirr ) passed over the sample for 0.25 h to surface oxidise the copper. At the end of this period the flow was switched to 10 % H2/N2 (50 entitlin 1) and the sample heated at a heating rate of 3 deg.min"1. The hydrogen up-take was quantified, from this a... 

In a 1.5-1. beaker (Note 1), 191 ml. (180 g.) of aqueous 25% dimethylamine solution (1.0 mole) is diluted with 64 ml. of water and treated with 116 g. (1.1 moles) of nitrourea.2 The temperature of the resulting brownish liquid rises spontaneously to 35-42°. The solution is warmed to 56-60°, and a reaction sets in vigorously with evolution of nitrous oxide. External cooling with water is applied when required the reaction temperature is maintained below 70° during the first 5-7 minutes and below 85° during the second period of 5-7 minutes. After a total of 10-15 minutes, the effervescence slackens and the reaction mixture is kept at 90-100° until the evolution of gas has completely ceased. This usually requires an additional 15-20 minutes. 

In 1732, H, Boerhaave 11 tried without success to condense air to the liquid state by artificial cold and in 1850, J. Natterer likewise failed in an attempted liquefaction of air, although he compressed the gas under nearly 3000 atm. press. but in 1877, L. Cailletet obtained liquid air in the form of a mist by compressing dried air, freed from carbon dioxide, at the temp, of liquid nitrous oxide, and under 200-225 atm. press., and suddenly releasing the press. and in 1884, J. Dewar described a method of liquefying air cooled by means of liquid or solid nitrous oxide —vide 1. 13, 25. Various forms of apparatus have been devised for liquefying air... 

Nitrous oxide gas is easily liquefied. In 1823, M. Faraday10 heated thoroughly dried ammonium nitrate in one leg of a A-tube, and on cooling the other leg of the tube, obtained two liquids one a soln. of nitrous oxide in water, and the other water in nitrous oxide. It is doubtful if J. H. Niemann prepared the liquid gas in in this way. The liquefaction by compression and cooling has been described by... 

Studiengesselschaft Kohle m.b.H. (2) reported the effect of temperature on solubility level in supercritical gas. The solubility is highest within 20 K of the critical temperature and decreases as temperature is raised to 100 K above the critical temperature. At temperatures near the critical temperature, a sharp rise in solubility occurs as the pressure is increased to the vicinity of the critical pressure and increases further as the pressure is further increased. Less volatile materials are taken up to a lesser extent than more volatile materials, so the vapor phase has a different solute composition than the residual material. There does not seem to be substantial heating or cooling effects upon loading of the supercritical gas. It is claimed that the chemical nature of the supercritical gas is of minor importance to the phenomenon of volatility amplification. Ethylene, ethane, carbon dioxide, nitrous oxide, propylene, propane, and ammonia were used to volatilize hydrocarbons found in heavy petroleum fractions. 

The design must consider three feed streams and two product streams. The three inlet feed streams are strong reaction gases, weak nitric acid solution and make-up water. Two outlet streams flow from the column. These are a lean reaction gas (tail-gas) stream and red product acid. Absorption of nitrous oxides increases as the temperature is reduced. This effect, together with the exothermic oxidation/ absorption reactions, requires installation of an internal cooling circuit. 

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