Dispersivity quotient

Thus, i) with the Ni-Ti samples, 3h of reduction at 573 K is enough to achieve about 100% of Ni metallic, ii) with Ni-Al, the same reduction treatment only allows us to reach 28% of the attainable Ni (this figure can be easily calculated as 1 minus the quotient of the area below the TPR curve of the pre-reduced sample and of the fresh one). This percentage correspons to the reduction of nickel with weak interaction with the support, iii) with (Ni-Al-Ti)imp and (Ni-Al-Ti)sg catalysts, reduction at 573 K also produces a small percentage of nickel reduction (21% and 17%, respectively), and iv) reduction at 773 K leads to an almost complete reduction of the Ni " into Ni (75%, 100%, 81% and 98% are the reduction percentages achieved in Ni-Al, Ni-Ti, (Ni-Al-Ti)imp and (Ni-Al-Ti)sg, respectively). Only the more dispersed Ni species firmly attached to the support remaining as non-reduced (e.g. NiAl204 in the case of Ni-Al). 

The first HTU term contains the physical and fluid-dynamic parameter and the second NTU term expresses the number of theoretical stages as function of the solute concentration difference. The extractor-specific HTU value is, on the one hand, described by the quotient of flow rate and cross-sectional area of the column, and, on the other hand, it is characterised by the interfacial area per unit volume and the mass transfer coefficient. The former is mainly influenced by drop size and phase hold-up, the latter by the relative movement of the dispersed phase. These characteristic HTU values can be experimentally measured for a certain extractor type and are used for comparison with other extractors or for the projection of larger units. 

Dispersive power is more constitutive than refractivity—a fact first recognized by Gladstone (1886, 1887) when investigating the quotients (w — nXl) d and M nXl — nX2)jd for additivity. Briihl (1891), using the Lorentz-Lorenz expression for the specific or molecular refractions, considerably extended the subject and prepared lists of atomic dispersions for the a and y hydrogen lines these were later revised by von Auwers and Eisenlohr. Tables such as those produced by the last-named author (1912, 1923) have always included values for Rp — Ra and Ry — Ra. Predicted dispersions are sometimes satisfactory when absorption wavelengths are well away from the visible region (e.g. from Table 2 Ry — Ra for acetyl chloride and pentyl alcohol are 0-44 and 0-64 cm3 the observed differences are 0 48 and 0-64 cm3 2 ... 

In these two equations r/ad, is the viscosity of the adsorbed polymer, >i2e the (non-equilibrium) excess interfacial tension and y,2 the (equilibrium) interfacia] tension, so that the quotient yi2j i2 describes the distance of the thermodynamic system from the equilibrium state. It is ea.sy to see that such behaviour is not at all in accordance with the idea of statistically distributed dispersed phases and non-interacting interfaces. 

Table 42 shows values for this quotient if they are small compared with unity, as is usually the case, the dispersion effect is predominant, if thej/ reach unity or over, the influence of the permanent dipoles prevails. 

Figure 7-8. Quotient dj/ a/ (Ap g) as function of specific flow rate of the dispersed phase uq, valid for 25 and 50 mm tube columns stacked aligned with metal Biatecki rings made [11, 12]...

Fig. 16. (A) Dispersion of the wave speed as a function of the controller level tJmin. This level is seen by the propagator in the ID case for various f values and e = 0.01. The dots close to a dispersion curve indicate the speed and minimum v value of the corresponding 2D spiral wave. (B) Ratio of the controller amplitude Ac at the center and An at a point far outside. The quotients of integers give the corresponding frequency ratios /c//o.

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