Pore area median

The pore diameter on the abscissa is calculated by employing a particular pore model, usually to the intrusion branch. As a matter of convenience, a cylindrical pore model is traditionally applied. On the ordinate, steep changes in the cumulative diagram are reflected as peak maxima in the incremental curve. From several possible representations (incremental, differential, log differential), the log differential plot seems to be the most revealing, since the areas under the peaks are proportional to the pore volume [79]. Data that can easily derived from mercury intrusion are the pore size distribution, median or average pore size, pore volume, pore area, bulk and skeletal density, and porosity. 

Fluorination of this catalyst altered the pore structure in the following way. The sample pore volume increased from 0.78 to 1.42 cc. per gram, and the median pore radius increased to 154 A. However, the BET surface area of the sample remained close to 228 sq. meters per gram. The total calculated pore area changed only from 226 to 216 sq. meters per gram. The surface area had probably de-... 

Properties Specific surface area, median particle diameter (see Table 3.773). Detailed chemical analysis, particle size distribution, and pore volumes and diameters available [186]. 

The surface separation in the slit-shaped pore is determined by the crystal thickness. For an illite [a fine-grained mica with a surface area of 1.6 X 10 m per kg], the slit-shaped pores have a median size of about 5nm and in the overlap pores the surface separation is about Inm. The stability of day domains within a soil is a crucial feature for agricultural production because the permeability of a soil to aqueous electrolyte solutions depends on this stability. Swelling of these domains reduces permeability. 

Catalyst Fraction Density Limit, g/cc Median Density, z/cc % of Total BET SA m2/g Cum Por Vol. cc/g, Avg Pore Radius, A Micropore Volume, cc/e Micropore Area, m2/ Matrix Area, m2/ ... 

This relatively large surface area and the fact that the isotheim is of Type IV indicate that this film has porosity in the mesoporous range. A pore size distribution using the desorption branch of the isotherm is shown in Figure 4.16 (page 190). A fairly unimodal distribution is obtained with a median pore diameter of... 

The supports used for the various compositions were low surface area, fused alpha-Al203 carriers typically used for supported silver catalysts. Surface areas ranged from 0.2-1.0 m/gm with pore volumes between 0.4-0.6 cc/gm median pore diameters ranged from 1-10 microns. Most catalysts were prepared on shaped carriers, which were sieved to give a narrow range of granules before evaluation. 

The commercial Co-Mo catalysts used for hydrocracking oil sands bitumen and petroleum residua are normally supported on alumina. Several years ago hydrodesulphurization (HDS) studies with thiophene ref. 1) indicated that carbon supported catalysts were superior to alumina supported ones. However HDS of benzothiophene (ref. 2) was found to be greater on alumina supported catalysts than on carbon supported ones. Studies of these two supports were performed in our laboratory with Athabasca bitumen (ref. 3). Care was required in choosing the particular carbon support, since carbons which have very large surface areas also have small pore si2es which would inhibit or perhaps exclude some of the larger molecular species in resid feedstocks, such as Athabasca bitumen The wide pore carbon that was available, had a surface area and a median pore diameter that were respectively half and more than double those of the alumina support used for comparison,... 

Figure 4. Effect of CO2 pressure on on morphology of macroporous crosslinked polymer monolith, (a) BET surface area (continuous line = total surface area, hed line = micropore surface area) (b) Percent micropore volume (c) Median pore diameter (d) Intrusion volume (macropore volume).

It follows from all above said that carbon particles interact with the lead active mass, being adsorbed on its surface and/or incorporated in the bulk of the lead skeleton branches. This results in macrostructural changes (reduced median pore radius and increased specific surface area of NAM). Thus, carbon additives alter the very nature of the lead electrode, converting it into a lead—carbon electrode, which will inevitably affect its electrochemical behaviour. The latter will depend on the affinity of carbon to lead, on the electrical conductivity of the carbon additive and on the electrochemical properties of the carbon surface. 

The ability of surface acoustic wave (SAW) devices to monitor adsorption of Nj onto the surfaces of porous films and diffusion of species Into polymer films has been demonstrated. Calculations based on the N2 adsorption Isotherms Illustrate how sol-gel solution chemistry can be used to tailor the surface area and pore size distribution of thin films. BET surface areas from unity to over 30 cm /cm of film have been obtained on various samples with median pore diameters from less than 0.4 nm to greater than 6 nm. SAW frequency transients occurring during the diffusion of small molecular species Into polymer films have been used to determine diffusion coefficients from 10 to 10 cm /sec. 

Specific reaction conditions determined the extent of reaction that had taken place. The particle size distribution of this powder is shown in Figure 2.15 and was determined to be 7-30 0,m with a median of 18.5 p,m. The surface area of the powder was 60 m /g, which indicated that the powder had a high porosity with a pore volume of 1.16 cm /g. 

Sample Aging Times Refractive Index Porosity" (%) Median Pore" Radius (nm) Surface Area" (mVg)... 

Pore distribution in sepiolite remains almost unaltered through sulphurization, in spite of the variations shown in Fig. 2b and Table 2. Only a decrease in the 10-100 pm range in favour of that of 0.025-0.25 is appreciated. This distribution can be related to a gradual filling of all pore sizes, resulting in a large decrease in surface area and pore volume that leaves nearly constant the values of mean, median and mode pore radius. The rate of sulphur deposition should decrease in line with the fall in accessible sulphur (Fig. 1). 

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