Oxygen versus temperature

Works [40, 91] surveyed y versus temperature for deactivation of 02( Aj ) on quartz at 350- 900 K. The obtained temperature dependencies were in the Arrhenius form with the activation energy of 18.5kJ/mole. A conclusion was drawn up about the chemisorption mechanism of singlet oxygen deactivation on quartz surface. A similar inference was arrived at by the authors of work [92] relative to 02( A ) deactivation (on a surface of oxygen-annealed gold). 

Fig. 5.12. Coefficient of heterogeneous deactivation of singlet oxygen versus the temperature of zinc oxide surface at Pqj = 0.1 Torr [102]...

When the right-hand side of the above equation is zero, i.e., when either T = 0 or P0j equals one atmosphere, AG° must be zero. The intersection of the standard free energy change versus temperature line with the temperature axis, when AG° = 0, gives the temperature at which the oxygen equilibrium pressure, P0i, is equal to one atmosphere. This temperature is known as the decomposition temperature of the oxide and is denoted as TD on line 1 in Figure 3.5. 

A standard free energy versus temperature diagram for oxides is often presented with a scale for oxygen pressures. Such a diagram is shown in Figure 3.6. This scale is designed to... 

Table III. Oxygen Index for FRC Materials Versus Temperature ...

Figure 7.7 Equilibrium oxygen partial pressure for a nonstoichiometric oxide YBa2Cu3Ox (a) composition, x, versus temperature under an oxygen partial pressure of 1 bar (b) oxygen partial pressure versus temperature for a composition of YBa2Cu306.5 and (c) oxygen partial pressure versus composition, x, for a temperature of 600°C. [Adapted from data in P. Karen, J. Solid State Chem., 179, 3167-3183 (2006).]...

Figure 4.24 Relationship between the partial pressure of oxygen and the composition of CO-CO2 and H2-H2O gas mixtures at 1 bar. (a) Pco PcO-, versus temperature and (b) Pyi2IPw-X) versus temperature at selected partial pressures of oxygen. Thermodynamic data are taken from reference [21].

Examples of oxygen permeability versus crystallinity for 0 and 100% hygrometry (c). EVOH Example of oxygen permeabilities versus temperatures (°C)... 

FIGURE 15.2 Catalyst regeneration versus excess oxygen and temperature. 

In Figure 2.4 the response to NH3 versus temperature shows characteristic differences for the two different catalytic metals, Ir and Pt [51, 52]. The NH3 response is larger over a wider temperature range for Ir compared with Pt. Also, the increase in temperature at which maximum sensitivity occurs as a function of NHj concentration is more pronounced for Ir than for Pt. The difference in catalytic activity between Pt and Ir has been confirmed previously [53, 54]. Literature reports differences in the oxygen adsorption on these two metals, which may be one reason for the differences seen here [55, 56]. 

Fig. 1.29 An oxygen pressure versus temperature diagram for the CrO2 phase region in the Cr-O system. ...

Fig. 1.31 An oxygen pressure versus temperature curve for CrOs (50 g) sealed in a 36 cm high pressure cylinder. ...

The value of non-stoichiometry d in Nii O is 1 x 10 at most, that is, there is only one vacancy in 1000 lattice points of Ni. Osburn and Vest measured the electrical conductivity, a, of high purity NiO (single crystal) as a function of temperature (1000-1400 °C) and oxygen partial pressure (1—10 atm), to elucidate the conduction mechanism. Figure 1,38 shows a versus temperature curves at fixed Po. values. The following relation between measured temperature, T, and oxygen... 

A plot of the volume versus temperature (at constant pressure) for hydrogen, H2, and oxygen, Oz, in their gaseous phases. Note how the gases converge to zero volume at the same temperature, -273.13°C. 

Fig. 11. Oxygen ion conductivity versus temperature for selected electrolytes. From ref. [50].

Water is decomposed into hydrogen and oxygen as the net result of the Cu-CI thermochemical cycle. The cycle involves five steps, as listed in Table 1 1) HCl(g) production using equipment such as a fluidised bed 2) oxygen production 3) copper (Cu) production 4) drying 5) hydrogen production. Recent studies by Chukwu, et al. (2008) and Orhan, et al. (2008) have analysed the overall thermal efficiency of the five-step Cu-CI cycle. The efficiency of the cycle versus temperature was analysed for three cases x = 0.2, 0.3 and 0.4, where x refers to the fraction of heat loss to heat input to the cycle. The calculated efficiencies varied from 42 to 55% at 550°C. 

Table 5-22. Oxygen versus carbon alkylation in the reaction of two sodium are-nolates with haloalkanes at room temperature [370, 371],...

The higher the percentage of oxygen, or the higher the deposition temperature, the more complete is the combustion (oxidation) that occurs. The oxidant-to-fuel (solvent) ratio helps to control the flame temperature, size and velocity. Using pure oxygen versus air results in a more efficient and rapid combustion this in turn minimizes the formation of NO, carbon monoxide, and elemental carbon. 

Thermogravimetric Analysis (TGA). TGA follows the loss in weight of a sample as it is heated, and measures the amount of volatUes versus temperature. Carried to pyrolysis temperature, in nitrogen or in oxygen, it can be used to determine the percent of organic matrix versus inorganic fillers, as well as percent moisture or solvents. 

Figures 5a-f plot the product of the MA and n-butane pulse areas (i.e., the relative MA selectivity) versus the n-butane pulse number. Taken together, these plots show that the MA selectivity depends on the pulse number, and the oxygen treatment temperature...

Fig. 16. Mass change versus temperature forTiAl oxidized for 58 hours in air, oxygen, and oxygen which is contaminated with a small amount of nitrogen. Air and 02(N2) curves are for 54 at% A1 and 02 curve is for 52 at% Al.

Figure 2-19. Oxygen partial pressure versus temperature phase diagram for YBCO films. (From Zhao et al. [144].)...

Due to space limitations it is not possible to show the evolution of gaseous concentrations during all regeneration experiments. A representative evolution of gaseous concentrations versus temperature, measured downstream of the filter samples (Sample No. 6) is presented in Figure 7. As explained above all available oxygen under the conditions of the experiment is consumed by CO and THC oxidation below 650°C. 

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