Surface area development

By cross-plotting the data in Figs. 13 and 14, the relation between the specific surface area and the porosity of the carbon rods after reaction at different temperatures can be presented, as in Fig. 15. It is seen that the surface area developed in the rods is not only a function of the porosity developed but also a function of the reaction temperature. The development... 

No attempt is made here to explain the intricate temperature dependence of the hydrations of the three calcium silicates. Work on the kinetics of these hydration processes is not complete, so the authors could give at present only highly tentative and speculative explanations. The conclusion from Figures 2 to 7 for the purposes of this paper is that the surface area development in pastes of all three silicates is determined primarily by the degree of hydration of the silicate. For a simple reaction, in which the reactants have negligible surface areas compared with the reaction products, such a conclusion would be trivial. However, for as complex... 

The specific surface area (5, m /g) including the geometric surface of the grains, which depends on the granulometric distribution and their form, and the surface area developed by the pore walls... 

Figure 7 shows that the development of microporosity is very significant in the wood chars. Just as it was in the cellulose char. In fact, a very similar pattern of surface area development is seen in the wood chars as in the cellulose chars. 

This chapter is concerned with the energetics of gas adsorption on carbons, or more specifically the thermodynamic quantities involved when carbon materials are employed as the adsorbents. Out of these solids, activated carbons, due to their exceptional surface area development and consequent technological implications, are the carbonaceous adsorbents that have attracted the attention of most publications. A more comprehensive account of the energetic aspects of adsorption on carbons has been published elsewhere [1]. 

Two aluminum oxide samples were used in the experimental studies. Results relative to the interfacial characteristics reported in B were obtained employing the rough industrial sample of specific area equal to 3.0 m2/g. Those relative to the colloidal stability reported in A were obtained employing a fractionated sample of specific area equal to 2.35 m2/g. The correspondence between the interfacial characteristics of the polymer coated particles and their colloidal stability is established as a function of the degree of polymer coating expressed in terms of mg/m2. However, the correspondence cannot be strictly established on the basis of the specific surface areas as far as the polymer doses relate to the surface area developed by the peptized oxide, which is only available prior to aggregation. Fortunately, comparing the instability domains of the two samples leads us to see that polymer doses determined for the fractionated sample must be multiplied... 

The relatively high newly developed mesopore surface area of 120 m g is however in contrast to alkaline-treated silicalite-1, in which despite the high degree of unselective silicon dissolution hardly any mesoporosity has been observed. Due to the uncontrolled silicon extraction in the absence of framework aluminum, mostly large macropores were obtained in alkaline-treated silicalite [18]. We have previously reported a correlation between mesopore surface area development and framework Si/Al ratio of the parent... 

The proper activation condition provide an oxidation which selectively erodes the sur ce so as to increase the surface area, develop greater porosity, and leave the remaining atoms arranged m configurations that have specific affinftfes (54). 

In contrast to IGC-ID, a measurable amount of probe is injected in the column resulting in a large range of coverage ratios of the solid surface by the probe. Injections of liquid probe of a few microliters are required for ICG in finite concentration conditions. The injected volume is mainly dependent on the surface area developed by the solid in the chromatographic column, and on the measurement temperature. 

ASC = Mti (lEPsi - IEPtj/Si)/(Msi(IEPr,/si-IEPTi) - MTi(IEPTi/Si-IEPsi)) where Mji and M i are the molecular weights of titania and silica respectively, and the subscripts Si and Ti/Si refer to the silica and titania-silica samples, respectively, llie surface area developed by the supported TiOa was calculated as the product of ASC value and BET value of the sample. 

Carbon dioxide isotherms at room temperature, and the corresponding surface areas estimated by the Dubinin-Radushkevich equation, are shown in Figures 21 and 22 as a function of reaction time and temperature. CO2 surface areas changed only slightly with CsHe reaction time and ranged between 130 and 170 m /g at 500°C, and 104 to 164 m /g at 700°C. For all samples, no distinct trends are identified on the possible effect of temperature and cracking reaction time on CO2 surface area development. 

Equations (2) and (25) are difficult to work with because values of aFe /aFe or (Fe +l/IFe ] are required. These are generally not measured. Hence, further development of kinetics treatments, with an eye toward eliminating the dependence of the rate on aFe /aFe, appears to be in order. Parametric studies may reveal an appropriate correlation of aFe /aFe with commonly measured properties. Also, the surface area development term in Equations (16), (21), and (24), that is, a"X1 - a), must be rewritten in more fundamental terms so that bulk magnetite as well as powdered magnetite may be adequately described by these relations. The porosity and cylindrical pore models of Simons and Petersen, respectively, may serve this purpose. 

Gasification kinetics during entrained flow gasification Part II - intrinsic char reaction rate and surface area development. Fuel, 107, 653-661. 

The drop size achieved is important in estimating the mass-transfer surface area developed in the dispersion. In certain situations, the surface area of the dispersion per unit volume of the total liquid phase, a, is available from measurements. The average or mean drop size appropriately defined can then be related to For example, the Sauter mean diameter ( 2 of the drop size number density distribution has been related to via the following relation and the dispersed phase volume fraction... 

When a remote control operates, spill-over oxygen must flow easily from one phase to the other. The number of contacts between the small domains of different chemical composition should thus be large and the quality of the contacts excellent for permitting an easy "jump" of spill over species from one phase to the other. The formation of the spill-ovo species depends on the surface area developed by the phase dissociating oxygen (e.g. Sb204). The number of sites to create on the catalytic phase (e.g. M0O3) depends on the surface area of that last phase. A second very important parameter is thus the phase A hase B surface area ratio. 

The surface area developped by antimony oxide over the surface of the support can be calculated by the difference, after reaction, between the surface area of the impregnated support and that of the pure support. For example, in the case of lSb/Sn02, the antimony oxide develops a total... 

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