Deactivation index

On the other hand, Spitz 45,97) found strong variations in the deactivation index upon variation of concentration and nature of the external donor. Therefore,... 

As with the polysulphones, the deactivated aromatic nature of the polymer leads to a high degree of oxidative stability, with an indicated UL Temperature Index in excess of 250°C for PEEKK. The only other melt-processable polymers in the same league are poly(phenylene sulphides) and certain liquid crystal polyesters (see Chapter 25). 

Being applied for the relaxation of populations (k = 0), this equality expresses the demands of the detailed balance principle. This is simply a generalization of Eq. (4.25), which establishes the well-known relation between rates of excitation and deactivation for the rotational spectrum. It is much more important that equality (5.21) holds not only for k = 0 but also for k = 1 when it deals with relaxation of angular momentum J and the elements should not be attributed any obvious physical sense. The non-triviality of this generalization is emphasized by the fact that it is impossible to extend it to the elements of the four-index... 

If the mixture to be separated contains fairly polar materials, the silica may need to be deactivated by a more polar solvent such as ethyl acetate, propanol or even methanol. As already discussed, polar solutes are avidly adsorbed by silica gel and thus the optimum concentration is likely to be low, e.g. l-4%v/v and consequently, a little difficult to control in a reproducible manner. Ethyl acetate is the most useful moderator as it is significantly less polar than propanol or methanol and thus, more controllable, but unfortunately adsorbs in the UV range and can only be used in the mobile phase at concentrations up to about 5%v/v. Above this concentration the mobile phase may be opaque to the detector and thus, the solutes will not be discernible against the background adsorption of the mobile phase. If a detector such as the refractive index detector is employed then there is no restriction on the concentration of the moderator. Propanol and methanol are transparent in the UV so their presence does not effect the performance of a UV detector. However, their polarity is much greater than that of ethyl acetate and thus, the adjustment of the optimum moderator concentration is more difficult and not easy to reproduce accurately. For more polar mixtures it is better to explore the possibility of a reverse phase (which will be discussed shortly) than attempt to utilize silica gel out of the range of solutes for which it is appropriate. 

B bulk property d deactivation e effective property G gas phase i component index i reaction index L liquid phase p catalyst particle property equilibrium conditions... 

There have been some examples of the use of LDMS applied to the analysis of compounds separated via TLC, although not specifically dealing with polymer additives [852]. Dewey and Finney [838] have described direct TLC-spectroscopy and TLC-LMMS as applied to the analysis of lubricating oil additives (phenolic and amine antioxidants, detergents, dispersants, viscosity index improvers, corrosion inhibitors and metal deactivators). Also a series of general organics and ionic surfactants were analysed by means of direct normal-phase HPTLC-LMMS [837]. Novak and Hercules [858] have... 

The results on olefin isomers (Table Vll) can also be explained by the observation that the constraint index of ZSM-5 is approximately unity under the conditions of this study. Shape selectivity or preferential conversion of straight chain olefins by ZSM-5 cannot be expected at 500 C. Thus, under the conditions of this study, olefin isomer distribution was not significantly affected by deactivated ZSM-5. At temperatures lower than that employed in the present study, it is conceivable that distribution of olefin isomers could be altered by steam deactivated ZSM-5. 

Figure 4. Effect of regenerator temperature on the Davison SOx Index for a blend of DA-250 + 10% Additive R + 0.37% CP-3. The blend was steam-deactivated at 1350 F, 100% steam, 15 psig, 8 hrs.

Sadana and collaborators (Sadana, Raju and Shahin, 1989) have proposed an empirical stability index (SI) for enzyme deactivation, which makes more quantitative the effect of different variables on enzyme stability. 

Sadana, A., Raju, R.R. and Shahin, E. (1989) A stability index for enzyme deactivation. 

Several benzyl derivatives exhibit potentially hazardous properties arising from the activation by the adjacent phenyl group, either of the substituent or of a hydrogen atom. Halides, in particular, are prone to autocatalytic Friedel Crafts polymerisation if the aromatic nucleus is not deactivated by electron withdrawing substituents. Individually indexed compounds are ... 

Selection of the final candidate for development was based on various properties. In addition to the therapeutic index, availability, synthesis, and softness (the rate and easiness of metabolic deactivation) also had to be considered. Loteprednol etabonate (4, chloromethyl 17a-ethoxycarbonyloxy-l lp-hydroxy-3-oxoandrosta-1,4-diene, 17P-carboxylate 1 A1, R = CH2C1, R2 = COOC2H5,... 

The performance indexes, which define an optimal catalyst distribution, include effectiveness, selectivity, yield and deactivation rate. The key parameters, affecting the choice of the optimal catalyst profile, are the reaction kinetics, the transport resistances, and the production cost of the catalyst. An extensive review of the theoretical and experimental developments in this area is available [20]. Two typical examples to demonstrate the importance of an appropriate distribution of the active components are now described. 

Column. 2.5% SE-30 on 80-100 mesh Chromosorb G (acid-washed and dimethyldichlorosilane-treated), 2 m X 4 mm internal diameter glass column. It is essential that the support is fully deactivated. Column Temperature. Normally between 100° and 300°. As an approximate guide, the temperature to use is the retention index —10. 

The electrophilicity index also accounts for the electrophilic activation/deactivation effects promoted by EW and electron-releasing substituents even beyond the case of cycloaddition processes. These effects are assessed as responses at the active site of the molecules. The empirical Hammett-like relationships found between the global and local electrophilicity indexes and the reaction rate coefficients correctly account for the substrate selectivity in Friedel-Crafts reactions, the reactivity of carbenium ions, the hydrolysis of esters, the reactivity at the carbon-carbon double bonds in conjugated Michael additions, the philicity pattern of carbenes and the superelectrophilicity of nitronium, oxonium and carboxonium ions. This last application is a very promising area of application. The enhanced electrophilicity pattern in these series results from... 

Fig. 8 illustrates the variation of and with the coke content for consecutive coking. The index d indicates that, besides deactivation, diffusional limitations also affect the rate of transformation of A. The steep drop in activity corresponds to a coke content at which the... 

To clarify the difference, the selectivity of NO reduction by CO versus CO oxidation by O2, considered to be the best index of the difference, was measured for fresh, heat-treated and used catalysts. The results are shown in Fig. 2. Here, the closer to the lower right comer the curve is, the lower the selectivity of NO reduction. The A/F s correspond to X = 1.015 at the origin and to X= 1.000 at the upper right comer. The CO conversion was 100% at every point between these two points. At the points near the stoichiometric A/F, at which the selectivity of NO reduction is most important, the curve for the catalyst heated at 1173 K or 1273 K is almost identical to that for the fresh catalyst, but the selectivity of NO reduction on the used catalyst is distinguishably lower. Thus, clearly a decrease in NO reduction selectivity, not explainable by thermal deactivation, occurs on the used catalyst. 

New Developments in FCC Catalyst Deactivation by Metals Metals Mobility and the Vanadium Mobility Index (VMI)... 

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