Brunauer-Emmett-Teller method,

EA = elemental analysis IR = infrared spectroscopy PXRD = powder X-ray diffraction BET = Brunauer-Emmett-Teller method (specific BET surface area) and BJH = Barrett-)oyner-Halenda method (determination of pore volume and diameter), both determined by nitrogen physisorption ... 

TABLE 9.2 Values of Asp and c as Determined in 10 Different Laboratories by the Brunauer-Emmett-Teller Method for the Same Silica Sample Shown in Figure 9.9... 

Surface area Nitrogen adsorption multipoint Brunauer-Emmett-Teller method... 

The heats of adsorption of nitrogen on evaporated metal films of nickel and iron have been reported to decrease from 10 to 5 kcal./mole as the surface coverage increased from about 0.1 to 1.0 monolayer. Beeck (150) states that nitrogen is unsuitable for the evaluation of surface areas of evaporated iron and nickel films by the Brunauer-Emmett-Teller method because of its high heat of adsorption at 78°K., which would yield a value for monolayer adsorption too high by 50%. The author feels that this objection does not apply to the nitrogen adsorption on reduced electropolished planar copper plates for the following reasons. 

Various gas and liquid adsorption techniques are used to determine the porosity of a specimen. They are mostly based on the Brunauer-Emmett-Teller method (BET) [14]. Atoms or molecules penetrate into a sample through interconnected pores with links to the sample surface. The adsorbed volume and temperature and pressure dependent data are used to quantify the porosity and surface to volume ratios, which contain information about the pore size distribution [15]. A recent review is published by Schneider [11], Care must be taken that the used probe (gas or liquid) does not react with the sample. When pores become too small, the probe may not penetrate into them. Pores or interconnected pores are not detected, when no connection to the sample surface exists. For example, thin capping layers would close all pores and render the technique useless, even though the pores may be totally interconnected below the cap. 

BET Brunauer-Emmett-Teller method PEN-1 Soviet grade of epoxide-novolac... 

The present article deals primarily with the elucidation of the surface nature of common metallic and oxidic catalysts, and with statistical-mechanical investigations of the chemisorption equilibrium on these catalysts. The surface areas of these catalysts as determined by the Brunauer-Emmett-Teller method have been taken into consideration. It was shown that a number of certain metallic catalysts such as nickel, cobalt, and platinum and also oxide catalysts of the spinel type act as an array of homogeneous active sites. There is no reason to believe that a few limited regions of the surfaces of these catalysts, such as corners, edges, lattice defects, etc. are particularly important for their catalytic activity. This conclusion is in accordance with the poisoning experiments of Maxted et al. There is some evidence that the surfaces of these catalysts... 

Brunauer-Emmett-Teller, method, 581 Buffers, effect on specific adsorption, 324 Bunsenite... 

The point-R method of estimating surface areas was frequently used prior to the development of the Brunauer-Emmett-Teller approach. It entailed choosing from an absorption diagram such as Fig. 8-3 the point at which the central linear section begins. This procedure worked well for some systems, but it was extremely difficult, if not impossible, to select a reliable point B on an isotherm such as that shown for n-butane in Fig. 8-3. In contrast, the Brunauer-Emmett-Teller method was found to be reasonably satisfactory for this type of isotherm. 

BET Brunauer, Emmett, Teller method of measuring surface area... 

Reaction conditions 20% w/v TRIM based on volume of H2O, 2,2"-azobisisobutyronitrile (AIBN, 2% w/v), 0.5% w/v poly(vinyl alcohol) (88% hydrolyzed, 88,000 g/mol), 60 C, 6h. Mean diameter calculated fiom >100 particles. Measured by mercury intrusion porosimetry over the pore size range 7 nm-20 pm. Measured by N2 adsorption desorption using the Brunauer-Emmett-Teller method. 

The BET surface area of powder samples was determined by applying the standard Brunauer-Emmett-Teller method to the nitrogen adsorption isotherm obtained at -196°C using a Quantachrome, Nova 2000e (Boynton Beach, FL) instrument... 

The specific surface area of the powders (expressed in m g usually measured by Brunauer-Emmett-Teller method of nitrogen adsorption— BET) is inversely proportional to their median particle diameter (dso). 

A commercial neutral AI2O3 powder was used (Merck, 1077, particle size 0.063A).200 mm). The specific surface area of the oxide powder, determiued by the N2-Brunauer-Emmett-Teller method was 156 9 m g while by a methylene blue adsorption method 17 3 m g was obtained. 

Another technique commonly used to measure the powder surface area and the pore size is the physical gas adsorption technique based on the well-known BET (Brunauer-Emmett-Teller) method on monolayer coverage of adsorptives such as nitrogen, krypton, and argon. The application is very well established, and detailed discussions are available in Allen (1975). 

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