Diluted oxygen

The sieves slowly lose capacity and are regenerated about by burning with dilute oxygen. The process is capable of recovering n-paraffms up to Cjo. 

A number of investigations of the copper-group oxides and dioxygen complexes have been reported. The electronic spectra of CuO, AgO, and AuO were recorded in rare-gas matrices (9), and it was found that the three oxides could be formed effectively by cocondensation of the metal atoms with a dilute, oxygen matrix, followed by near-ultraviolet excitation. The effective wavelengths for CuO or AgO formation were X > 300 nm and for AuO was X > 200 nm. In addition, the laser fluorescence spectrum of CuO in solid Ar has been recorded (97). 

Regenerahility often is also a requirement. In the life cycle of a catalyst the most severe conditions are not always the reaction conditions regeneration conditions may well be more severe that the regular reaction conditions. Examples are hydrogenation catalysts that are regenerated by oxidative treatment in diluted oxygen. These catalysts must be resistant to oxidative treatment at high temperatures. This makes alumina a suitable carrier for these processes. 

Maximum effect of mixing in different liquids is observed at different concentrations of diluted oxygen. For example, in methanol this concentration is equal to 2-tO volume % (in other solvents this value may be different). These conecentrations are called the critical concentrations and are denoted. At oxygen concentrations above the... 

Such an electrochemical arrangement can also be used to transport oxygen from one electrode to the other by the imposition of an externally applied potential. This technique, known as coulometric titration , has been used to prepare flowing gas mixtures of oxygen/argon with a controlled oxygen partial pressure, to vary the non-stoichiometry of oxides, to study the thermodynamics of dilute oxygen solutions in metals, and to measure the kinetics of metal oxidation, as examples. 

The direct reaction between a substrate adsorbed on the surface of the semiconductor and the hvb or e b via electron transfer is typically not considered to be a significant reaction patliway in dilute oxygenated aqueous media. 

Dilute oxygen-free solutions of 4 (10 M) are stable up to 70°C, but in concentrated solutions polymerization occurs at and below room temperature. An interesting phenomenon was observed with temperature change whereas solutions are colorless at room temperature, they show a reversible yellow to pink coloration on cooling to dry ice/acetone (in CHCI3 and CCI4). ... 

The most important autoxidation used industrially is the synthesis of cumene hydroperoxide from cumene and air (i.e., diluted oxygen) (Figure 1.37). It is initiated by catalytic amounts of dibenzoyl peroxide as the radical initiator (cf. Figure 1.11). The cumyl radical is produced... 

Rubidium monoxide, Rb20.—When rubidium is partially oxidized by diluted oxygen, and the excess of metal removed by distillation, the... 

As will be pointed out later, catalysts and membranes may become gradually deactivated and, when this occurs, they need to be regenerated often by some combustion process using dilute oxygen. In cases where coke deposit becomes significant on the cat yst or the membrane and needs to be removed by combustion, the membrane reactors are potentially subject to thermochemical cycling as part of the normal operation. 

The commonly practiced method of regenerating coked catalysts or catalytic membranes is by combustion with air, air/stcam mixtures, air/nitrogen mixtures, or dilute oxygen streams with another carrier gas. 

The results of the calculations are presented in Table 2, which shows that infinitely dilute oxygen, carbon dioxide and methane molecules are preferentially hydrated in dilute aqueous solutions of sodium chloride. This means that water is in excess and sodium chloride is in deficit in the vicinity of a gas molecule in contrast with the random distribution of water and sodium chloride in their binary mixtures. The values of Awi2 and Aw32 are small because only the dilute region was considered in Table 2 (cj =0.3 corresponds to X3 = 0.0054). To carry out similar calculations in the nondilute region, experimental data regarding and are required and they are not available. 

When the concentration of chloride ions is high, the primary product of oxidation is chlorine gas. However, as the brine solution becomes dilute, oxygen gas becomes the primary product. 

Disulfides can also be produced by passing mixtures of the mercaptan and air (or dilute oxygen in an inert gas) over copper or cobalt oxide/molybdenum oxide catalysts at elevated temperatures. 

The actual application of this scheme to following the transformation of D-glucose in very dilute, oxygen-free, sodium hydroxide solutions proved, nevertheless, disappointing. The apparent n-mannose concentrations became negative soon after the reaction had begun, indicating the formation... 

The obtained equation is usually applied for the diluted oxygen solutions in the liquid metals [71] ... 

It is interesting to analyze the solids behavior after ageing in dilute oxygen flow for 5 h at 1000°C. 

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