Relative oxygen mobility

Oxides (BET area) Relative Oxygen Mobility at 400°C Relative Hydrogen Mobility at 75° C ... 

Table 8.4. Relative oxygen surface mobility for some oxides at 400°C (base 10 for alumina)...

The enhancement of the relaxation process in natural hydrated silicate minerals by paramagnetic species such as Fe may be due to their facilitating the interaction between the Si nucleus and the electron spin as a result of the relatively high mobility of the hydrated paramagnetic species. A similar effect has been reported in zeolites (Cook-son and Smith 1985, Klinowski etal. 1986), in which the relaxation rate is significantly shortened by the presence of paramagnetic oxygen molecules. 

Forni and Rossetti studied Lao-oCeo-iCoOs+a perovskites prepared by the flame hydrolysis (FH) method [27]. This was proved a high-surface-area, thermally resistant catalyst The partial substitution of La by Ce in such a cobaltite led to a relatively low suprafacial activity, but to a high bulk oxygen mobility, leading to high intrafacial activity for the catalytic flameless combustion of methane. 

A number of metals, such as copper, cobalt and h on, form a number of oxide layers during oxidation in air. Providing that interfacial thermodynamic equilibrium exists at the boundaries between the various oxide layers, the relative thicknesses of the oxides will depend on die relative diffusion coefficients of the mobile species as well as the oxygen potential gradients across each oxide layer. The flux of ions and electrons is given by Einstein s mobility equation for each diffusing species in each layer... 

Most organic reactions are done in solution, and it is therefore important to recognize some of the ways in which solvent can affect the course and rates of reactions. Some of the more common solvents can be roughly classified as in Table 4.10 on the basis of their structure and dielectric constant. There are important differences between protic solvents—solvents fliat contain relatively mobile protons such as those bonded to oxygen, nitrogen, or sulfur—and aprotic solvents, in which all hydrogens are bound to carbon. Similarly, polar solvents, those fliat have high dielectric constants, have effects on reaction rates that are different from those of nonpolar solvent media. 

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