Inaccessible Pore Characterization of Less-Crystalline Microporous Solids

Abstract

The pore structures of microporous carbon fibers having less-crystalline structures with different activation extents were examined by small-angle X-ray scattering (SAXS), N2 adsorption, and density measurements.The different kinds of porosities were associated with observable quantities and a new concept of an inaccessible pore was introduced. Inaccessible pores include closed pores and ultrapores which are accessible by He at 303 K but not by NZ at 77 K. The surface area of samples was determined by both the high-resolution a, plot of the N2 adsorption isotherm and the Debye-Bueche plot of the SAXS profile. The surface area a, from SAXS was greater than that a, from N2 adsorption. The difference a, -a, was associated with the volume and size of the inaccessible pores. The possibility for a general application of this inaccessible pore

Carbon Aerogels: a study with different models of the effect resorcinol/catalyst at different ratios after pyrolysis and the effect on textural properties

“…Figure 2d shows the nitrogen adsorption-desorption isotherms of N2 to -196 C for the series II: Aew400, AeW600, AeW800 and AeW1500. It is observed, that they are similar and correspond to Type I isotherms combined with those of type IV, in accordance with [20,22,46], that fit also to the recent recommendations suggested by the IUPAC [46]. The hysteresis loop is submitted to different ranges of relative pressure, according to the samples of aerogels thus: samples AeW400, AeW600 and AeW800 to relatively high pressures (0.4 to 1.0) and the sample AeW1500 to pressures of (0.1 to 0.9), which shows the development of mesopores, when using these relations of Na2CO3 as a catalyst during the synthesis of aerogel.…”

“…Several authors [15][16][17][18][19][20][21] have conducted studies to evaluate adequately and systematically porosity that develops in carbon materials by different methods, including the effect pore subtraction method (SPE) using the graphics high αs resolution, for N2 adsorption isotherms at 77 K by which they can properly evaluate the structure of micropores [15,19]. According to these authors, to apply the analysis of highresolution αs it is possible to find adequate information on the microporosity developed in the process of synthesis of aerogels, as well as of the mesoporosity [22] that are in good agreement with other methods that have been used for several decades [23][24][25].…”

Pore classification in the characterization of porous materials: A perspective

“…Numerous studies attempt to categorize pores in solid materials based on defined physical frames [4][5][6][7][8], but many more examples could be found in the literature [9][10][11][12]. It is difficult to give a consistent classification of porous structure in solid materials.…”

“…These arrangements can be categorized as interaggreation (intracluster) and intercluster pores as mentioned by J. Kodikara [9]. According to Ruike et al [11], the term "closed pore" is used for pores that cannot be penetrated by He at 303 K. The other interpretation of the term "closed pore" is an open pore whose width is smaller than the probe's molecular size (ultrapores). Such effectively closed pores and chemically closed pores should be designated as latent pores [8].…”

A multi-method study of the transformation of the carbonaceous skeleton of a polymer-based nanoporous carbon along the activation pathway

“…[13]), analysis of the small-r region of the PDF [43] (e.g. [65]), and from small-angle X-ray scattering (SAXS) [66,67]. The first of these approaches is unsuitable as it cannot probe the micropores that dominate the PFA-based carbons considered here [63].…”