Texture specific pore volume

Table 1 shows the textural properties of SBA-15 and the recrystallized samples Wy. These data reveal that sample WO do not contain micropores and their specific surface area Sbet), total specific pore volume (Vtot) and specific mesopore volume (V em) are, in comparison with those of SBA-15, markedly diminished. In the presence of water (samples W5 to W40), the Sbet, Viot and Vmso decrease with increasing water content, while the specific micropore volume (Fmicro) decreases with increasing water content from 0.048 mL/g for SBA-15 to 0.005 mL/g for sample W15, but starts to increase with further increase of the water content for sample W30 and W40. 

It can be further seen from Fig. 5 and Fig. 6 that prolongation of the additional thermal treatment from 24 (sample 4) to 48 h (sample 5), did not change significantly the textural properties of the mesophase of sample 4, therefore, they show nearly identical isotherms (Fig. 5) and pore radius distributions (Fig. 6). In addition, the specific surface area and the specific pore volume of sample 5 are 308 mVg and 1.416 cmVg, respectively, being practically the same when compared with those of sample 4. 

The most important parameter for the characterisation of the surface texture of dispersed solids are the specific surface area, the specific pore volume, the pore size distribution and the particle size distribution. 

The characterization of a solid must be considered at different levels. The first one is the sum of its textural characteristics which corresponds to the classical identification of the solid in terms of its granulometry, specific surface area, pore volume, porosity and density. 

Textural characterization was performed by N2 adsorption-desorption at 77 K using a Micromeritics ASAP 2010 analyzer. The samples were preheated under vacuum in three steps of Ih at 423 K, Ih at 513 K, and finally 4 h at 623 K. BET specific surface area, Sbet, was calculated using adsorption data in the relative pressure range, P/Po, from 0.05 to 0.2. Total pore volume, Vp , was estimated by Gurvitsch rule on the basis of the amount adsorbed at P/Po of about 0.95. The primary mesopore diameter, Dp, was evaluated using the BJH method from the desorption data of the isotherm. The primary mesopore volume, Vp, and the external surface area, Sext were determined using the t-plot method with the statistical film thickness curve of a macroporous silica gel [5]. 

Textural Parameters. Adsorption-desorption isotherms of N2 at 77K were determined in a Micromeritics ASAP 2010 with a micropore system. Prior to measurement, the samples were outgassed at 140 C for at least 16 h. The specific surface area was determined by the BET method, assuming that the area of a nitrogen molecule is 0.162 nm [12]. Micropore volume was calculated by the t-plot method using the Harkins and Jura [13] thickness. We used model isotherms calculated from density functional theory (DFT) to determine the pore size distributions and cumulative pore volume of the pillared samples by taking the adsorption branch of the experimental nitrogen isotherm, assuming slit-like pores [14]. 

The influence of phosphorus on catalyst textural parameters, such as specific surface area (SSA), pore diameter (PD), and pore volume, has been thoroughly investigated (25, 30, 38, 60, 62, 68, 69, 72, 73). The SSA decreases with phosphorus loading, irrespective of the preparation procedures. In particular, it was reported that NiMoP catalysts obtained by coimpregnation have greater SSA decreases than those prepared by sequential impregnation 74). 

The interpretation of adsorption-desorption isotherms provides a wealth of information on the texture of the adsorbent. The main parameters that can be assessed arc specific surface area, pore distribution, specific porous volume and information on the structure (pore shape, interconnection, etc.). The technique is highly suitable for the study of samples where the pore size is between approximately 2 and 50 nm, which corresponds to the mesoporous domain for which the adsorbed gas has liquid phase properties well described by thermodynamic models. 

One of the most important characteristics of a catalyst is its porous texture (specific surface area, pore volume, pore size and size distribution) which must allow good reactant and product circulations in the catalyst bulk. According to its use, it is necessary to give to a catalyst a tailor-made texture. As they present many advantages, silica-aluminas are widely used as matrices (for cracking catalysts) or supports (supported metals) of catalytic phases. 

The alcoholic solvent strongly influences the textural properties of products as the aliphatic chain of the alcohol increases the specific surface area, the pore volume and the mean pore size increase for all Si02/Al203. 

Characterizing the texture of products, that is, the average size of primary microparticles and the average distance between them, originating from measured total pore volume and specific surface area values as was suggested by Hradil [302], Wojaczynska and Kolarz [301] arrived at the conclusion that the primary particles are packed more densely in the binary copolymers. It was found that the porosity of the acrylonitrile copolymers, too, depends on the type of solvent that is being removed on drying the polymer beads. 

In organic TEABF electrolyte, good electrochemical performance and mechanical stability was observed for electrodes with 3.5 wt% of polyvinylpyrrolidone (PVP) binder [61]. This amount of PVP has a negligible impact on porous texture characteristics, with total pore volume of 0.71cm g as compared to 0.73 cm g for the as-received AC. ECs with AC-PVP, AC-PTFE, and AC-PVdF electrodes in 1 mol l" TEABF in PC exhibited specific capacitance values of 112, 107, and 70 Fg", respectively. Hence, this fluorine-free material appears... 

The textural characteristics (Table 3.2 Figure 3.9) show that APS-/ samples are not pure nanopo-rous but contributions of nanopores into the specific surface area and pore volume are predominant. Therefore, one could anticipate strong shielding effects for adsorbates located in narrow pores. 

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