N2 sorption measurements

N2 sorption measurements for calcined 3D SBA-15 without and with addition of TMB show typical IV isotherms with large type H, hysteresis loops and relative narrow mesopore distributions at mean size of 10.7 and 17.6 nm, respectively. It is interesting that the mean pore sizes calculated from the adsorption branches for 3D SBA-15 are much larger than that from the desorption branches. However, the mean pore sizes for conventional SBA-15 (<373 K) have almost the same values calculated from both adsorption and desorption branches, indicating that latter have perfect cylinder channels while the former do not. Furthermore, the cell parameters (13.0 or 10.4 nm) for 3D SBA-15 products with or without TMB are smaller than the pore sizes (17.6 or 10.7 nm). These results imply that 3D SBA-15 products have interconnections of channels. 

N2 sorption measurements for calcined mesoporous silica SBA-16L (413 K) with large window confirm that the window size of the cages can be opened. A representative isotherm for ealcined conventional SBA-16 prepared without TMB shows a type IV isotherm with typical Hj hysteresis loops, suggesting that the material consists of large cages connected with small size windows (<4 nm). ft should be noted that the window... 

The applicability of the Pt deposition precipitation technique (DP) on mesoporous silica has been evaluated and discussed. A detailed synthesis procedure is given, and a suitable support from the SBA-15 family has been identified. The material synthesized at the conditions described here was clearly able to withstand the severe conditions of the DP treatment, indicating improved hydrothermal stability. The incorporation of the active species was accomplished without compromising the structural integrity of the parent material, as monitored by XRD and N2-sorption measurements. Using UV-Vis diffuse reflectance spectroscopy we were able to detect the platinum surface complex that coexists with platinum nanoparticles on the impregnated solid. 

Figure 36.5. Physical data obtained for mesostructures prepared at 25 °C (left) and at 110 °C (right) with molar TEOS PTMOS ratios of 100 0 and 80 20 a) powder X-ray diffractograms of as-synthesized and extracted samples b) Si HPDEC NMR spectra of as-synthesized samples c) N2 sorption measurements on extracted samples.

N2 sorption isotherms were measured for the pure carrier and for all the immobilized complexes, respectively. Sorption isotherms and textural characteristics for pure and loaded samples are compared in Fig. 2.1.6.1 and Table 2.1.6.1. In all cases these isotherms presented the characteristic form of mesoporous materials. It is clear that the N2 adsorbed/desorbed volume was higher in the case of pure carrier than in the case of immobilized complexes. 

For TGA, a Setaram TGA-DTA 92 apparatus was used. Alternatively, a home-built apparatus was employed for TPD-MS. GC analysis was on a Chrompack CP-Sil-5 column, eventually coupled to a Fisons mass spectrometer. ESR spectra were recorded with a Bruker ESP-300 and a TE104 cavity at temperatures between 130 and 300 K. N2 sorption experiments were performed with an Omnisorp-100 instrument. The t-plot method was applied for the analysis of the pore volume. Solid state NMR spectra were recorded using a Bruker MSL 400 spectrometer at a resonance frequency of 100.61 MHz. Cross polarization was optimized with glycine as a reference. For the measurement of liquid samples, a Bruker AMX 300 system was used, operating at 300.13 and 75.47 MHz for iH and C, respectively. 

Methyl-modified MSU-1 mesostructures were prepared by one-pot strategy. The microstructure and the interfacial characteristic were measured with N2 sorption, IR, SiNMR, SEM, TEM, TGA and SAXS. The results showed that methyl groups have been incorporated into MSU-X silica framework and the surface and texture properties of the resultant materials varied with the amount of incorporated methyl groups. 

The characterization of these P-zeolite samples via N2-sorption (BET) revealed, that catalyst C only had micropores and a BET surface area of 640 m g whereas the two catalysts with a higher conversion had meso- and macroporous volumina resulting in a faster mass transport. The difference in the performance of samples A and B can be attributed to the highest BET surface area of A (750 m g ) in contrast to B (680 m g ). Additionally, TPD measurements revealed that the total amount of acidic sites on sample A was still higher than on sample B. A shape-selective effect in the microporous system might be also involved since the dialkoxylation of limonene occurs only to a minor extent. In order to... 

The N2 sorption isotherm measured for MCM-41 is distinctive, being a type IV isotherm, presenting an unusually sharp capillary condensation step (Fig. 9.17). MCM-41 type mesoporous silicas are highly porous, showing BET surface areas exceeding 1000 m g and pore volumes up to 1 cm g The pore sizes usually vary between 2 and 10 nm depending on the alkylammonium surfactant chain length, the presence of... 

An ASAP 2400 from Micromeritics Instrument Corporation was used to measure N2 sorption, BET surface area, and pore size distributions. 

Porosity measurements by the N2 sorption method were carried out on T iQy hybrids prepared by the fast gelation of hydrogensilesquioxane resin (Table 2). 

The sorption and the permeation of pure CO2, CH4, N2 and O2 through an ABS membrane (Lustran 246) have been measured (87). 

When the gas or vapor feed stream contains a component that is highly soluble in the polymer membrane and causes plasticization, then the selectivity as defined by Equation 4.6 will depend on the partial pressure or the amount of the plasticizing component sorbed into the membrane. Furthermore, pure-gas permeation measurements are generally not a good indicator of the separation performance, and mixed-gas permeation measurements will be needed [21-23]. Often, the mixed-gas selectivity is less than predicted from pure-gas measurements [8] however, the opposite has been observed [24], Competitive sorption effects can also compromise the prediction of mixed-gas behavior from pure-gas measurements [25], For gas pairs where each component is less condensable than C02, like 02/N2, it is generally safe to conclude that the selectivity characteristics can be accurately judged from pure-gas permeabilities at all reasonable pressures. When the gas pair involves a component more condensable than C02, plasticization is likely to be a factor and pure-gas data may not adequately reflect mixed-gas selectivity. When C02 is a component, the situation depends on the partial pressures and the nature of the polymer. 

The micropore volume is defined as the pore volume of the pores < 2 nm. Microporous volumes calculated from the application of the Dubinin-Radushkevich equation to the N2 adsorption isotherms at 77 K. The mean pore size of each sample obtained from N2 adsorption was determined by applying Dubinin-Radushkevich equation. The hydrogen sorption isotherms were measured with the High Speed Gas Sorption Analyser NOVA 1200 at 77 K in the pressure range 0-0.1 MPa. 

Characterization of the crosslinked polymer in the dry state [apparent density (16), surface measurement by N2-ad sorption (17,18), Hg-intrusion for measurement of the pore volume (iS)] is not conclusive for the properties as polymeric reagent, However, extensive knowledge about the porous structure and the accessibility of different regions in the polymer network can be obtained by gel-permeation chromatography (GPC) (20). GPC is used in an inverse mode. Well-characterized samples are keys for the pore structure. 

Experimentally measured pure-component adsorption characteristics of O2, N2, CO2, and SO2 on H-mordenite were correlated to predict the behavior of multicomponent mixture of these gases. These correlations, based upon the relationships developed by Myers and Prausnitz, were successfully substantiated experimentally. The CO2 and SO2, which are the predominantly adsorbed components, controlled the fate of the multi-component sorption. This prevailed even at the concentration levels where the pure-component data indicate comparable affinity for both the strongly and the weakly adsorbed species. Hence, indications are that adsorption may be effectively useful in exhaust gas cleanup processes. The temperature sensitivity of the pure components contributes significantly to the selectivity of the sieve for the various components, and the data obtained indicate that this also tends to favor the desired applications in pollution combat. 

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