Specific surface area nitrogen adsorption

The new composite (SC-155) and some of its precursors and derivatives were characterized by LOI (loss on ignition), XRD ( X ray diffraction), 1R (infrared spectra), BET specific surface area, nitrogen adsorption desorption isotherms, pore size distribution (mercury porosimetry), dynamic methylene blue adsorption and SEM (Scanning Electron... 

Another part of the sol was adjusted to pH 6 and aged for 1 hr at 25 C. then readjusted to pH 2. The particle size had grown to 23 A as indicated by a surface area of 1215 m g" . When this sol was dried in the same manner, the gel. which looked the same as the previous one, had a specific surface by nitrogen adsorption of 626m g- . 

Specific surface area of carbon blacks before and after graphitization, determined by electron microscopy (A,) end by nitrogen adsorption (A ]t... 

Another standard industry method for surface area is based on the adsorption of cetyltrimethylammonium bromide (CTAB) from aqueous solution. This is ASTM method D3765-85 (2). This method measures the specific surface area of carbon black exclusive of the internal area contained in micropores that are too small to admit the large CTAB molecules. Eor mbber-grade nonporous blacks the CTAB method gives excellent agreement with nitrogen surface areas. 

Nitrogen adsorption experiments showed a typical t)q5e I isotherm for activated carbon catalysts. For iron impregnated catalysts the specific surface area decreased fix>m 1088 m /g (0.5 wt% Fe ) to 1020 m /g (5.0 wt% Fe). No agglomerization of metal tin or tin oxide was observed from the SEM image of 5Fe-0.5Sn/AC catalyst (Fig. 1). In Fig. 2 iron oxides on the catalyst surface can be seen from the X-Ray diffractions. The peaks of tin or tin oxide cannot be investigated because the quantity of loaded tin is very small and the dispersion of tin particle is high on the support surface. 

Specific surface areas of the catalysts used were determined by nitrogen adsorption (77.4 K) employing BET method via Sorptomatic 1900 (Carlo-Erba). X-ray difiraction (XRD) patterns of powdered catalysts were carried out on a Siemens D500 (0 / 20) dififactometer with Cu K monochromatic radiation. For the temperature-programmed desorption (TPD) experiments the catalyst (0.3 g) was pre-treated at diflferent temperatures (100-700 °C) under helium flow (5-20 Nml min ) in a micro-catalytic tubular reactor for 3 hours. The treated sample was exposed to methanol vapor (0.01-0.10 kPa) for 2 hours at 260 °C. The system was cooled at room temperature under helium for 30 minutes and then heated at the rate of 4 °C min . Effluents were continuously analyzed using a quadruple mass spectrometer (type QMG420, Balzers AG). 

Activated carbon has high specific surface area with respect to its volume, and thus has high adsorption capacity. Activated carbon adsorption is considered to be one of the most versatile treatment technologies and can remove classical pollutants such as COD, TOC, BOD, and nitrogen, as well as toxic pollutants such as phenol, refractory organic compounds, VOCs, and soluble heavy metals.38 Activated alumina and peat have also demonstrated similar abilities. 

The specific surface area of the fresh and used catalysts was measured by nitrogen adsorption method (Sorptometer 1900, Carlo Erba Instruments). The catalysts were outgassed at 473 K prior to the measurements and the Dubinin equation was used to calculate the specific surface area. The acidity of investigated samples was measured by infrared spectroscopy (ATI Mattson FTIR) by using pyridine (>99.5%, a.r.) as a probe molecule for qualitative and quantitative determination of both Bronstcd and Lewis acid sites (further denoted as BAS and LAS). The amounts of BAS and LAS were calculated from the intensities of corresponding spectral bands by using the molar extinction coefficients reported by Emeis (23). Full details of the acidity measurements are provided elsewhere (22). 

The structure of the catalysts was characterized by X-ray diffraction, IR-spectroscopy and transmission electron microscopy, their thermal stability was followed by thermal analytical method. The specific surface area and pore size distribution of the samples were determined by nitrogen adsorption isotherms. 

Physisorption measurements showed that carbon nanomaterials exhibit rather meso- and macroporous structures (maximum micropore fraction, 15% see Table 2.1). The lowest specific surface area was measured with the platelet fiber catalyst exhibiting slightly more than 100 m2/g. The Co/HB material offers 120 m2/g of surface area, and the highest BET value was determined with the Co/ MW catalyst featuring nearly 290 m2/g. Carbon nanomaterials, though, are not really porous, as the space between the graphene layers is too small for nitrogen molecules to enter. The only location of adsorption is the external surface of the nanomaterials and the inner surface of the nanotubes. 

Simply calculating specific surface areas from the values in Tables 3-5 leads to apparent specific surface areas of approximately 400-500 m2/g [49,51], Specific surface areas obtained from similar analyses of nonpolar gas (nitrogen or krypton) adsorption studies, however, are typically in the range of 1 m2/g, independent of sample pretreatment. 

Calculate C and the specific surface area As of a material from the nitrogen adsorption isotherm according to the BET equation from the data points given in the figure. Use the ideal gas equation to convert the adsorbed volumes into moles (STP indicates that the volumes adsorbed are given for standard temperature and pressure, i.e., 273 K and 101.3 kPa). 

Likewise, the Haul and Dtimbgen method of measuring specific surface areas through nitrogen adsorption has developed into an industrial standard [8]. 

Prior to nitrogen adsorption experiment to determine surface properties, ACC sample was degassed at 130°C under vacuum (up to 10 torr) for 12 h. The adsorption data were obtained at the Central Laboratory of Middle East Technical University (METU) with a Quantachrome Autosoib-l-C/MS apparatus over a relative pressure ranging from 10" to 1. The BET specific surface area, total pore volume, micropore volume, mesopore volume, and pore size distribution, PSD, of ACC were yielded by using the software of the apparatus. 

Although there are several methods for analysis of nitrogen physisorption data, the most commonly used is BET surface area. Because for microporous materials the boundary conditions for multilayer adsorption are not fulfilled, the calculated BET surface area has no physical meaning. Such data should be considered proportional to the total micropore volume rather than the specific surface area. The Tplot method can be used to calculate the micropore volume and the mesopore... 

The distillation fractions were also analysed for their caibon and hydrogen contents using a Leco CHN Determinator which was also used for similar analysis of die used catalysts. The hydrocracked liquid and the used catalysts were analysed for their sulphur contents using a Leco Suli iur Determinator. Some specific surface area analysis by nitrogen adsorption was carried out on the used catalysts using a Micromeritics instrument... 

Nitrogen sorptiometry, also referred to as BET method (named after their inventors Brunauer [202], Brunauer and Emmet [203], and Teller and coworkers [204]), is an approach for the determination of the specific surface area of a (porous) support material based on the multilayer adsorption of nitrogen at the temperature of liquid nitrogen (77 K) according to following procedure ... 

The specific surface area was measured by nitrogen adsorption at -195 C. The cumene cracking reaction was conducted by pulse technique under the following conditions O.IO g catalyst, H, flow rate 75 ml/nin, pulse volume 1 ul. 

However, nitrogen adsorption reveals considerable differences, as shown in Fig. 5.14, in terms of surface area distribution of a 28-day hydrated C3S specimen [20], or of specific surface area as a function of hydration time... 

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