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Transport Parameters and Textural Properties of Porous Solids
Soukup, Karel ; Šolcová, Olga ; Schneider, Petr
Based on a study of a set of porous materials with wide range of mean pore radii (from 50 to 3000 nm) and mono- or bidisperse pore structure, transport characteristics and textural properties are compared. Structure characteristics relevant to transport processes were evaluated from multicomponent gas diffusion and gas permeation measurements. For data analysis the Mean Transport Pore Model (MTPM) based on Maxwell - Stefan diffusion equation and Weber permeation law was used. Two standard methods - physical adsorption of nitrogen and mercury porosimetry (ASAP2010M and AutoPore 9200, Micromeritics, USA) were used for determination of textural properties. Results from liquid expulsion permporometry that correspond to situation in industrial processes were also taken into account.
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Efektivní difuzivity a transportní charakteristiky monolitických automobilových konvertorů s nanesenou vrstvou katalyzátoru
Starý, T. ; Šolcová, Olga ; Schneider, Petr ; Marek, M. ; Schejbal, M.
The effective diffusivity in the pores of catalytic monolith was studied in single pellet-string columns by chromatographic technique. The column was packed with small monolith particles. Dispersion due to extra column effects was eliminated via convolution of responses for two column lenghts. The measurements were done for both cordierite support with alumina based washcoat. The effective diffusion coefficients for two tracer-carrier pairs were evaluated by fitting column response (chromatographic) peaks in time domain. Mean transport parameters were evaluated for both types of porous particles. Obtained mean transport pore radii are in reasonable agreement with pore size distribution from mercury porosimetry.
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Effective Transport Properties of Reconstructed Porous Catalysts
Salejová, G. ; Kosek, J. ; Šolcová, Olga ; Schneider, Petr
The structure of porous catalysts is traditionally characterized by textural analysis, such as mercury porosimetry and BET sorption isotherm. Moreover, the effective transport properties of porous catalysts could be measured in the Graham diffusion cell, in the permeation cell, etc. In this contribution the electron microscopy images of porous catalysts are systematically analyzed, the spatially 3D porous media are reconstructed and their effective transport properties evaluated and critically compared with experimental values of effective transport parameters.
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Transport Parameters of Porous Solids: Wicke-Kallenbach and Graham's Diffusion Cell
Soukup, Karel ; Šolcová, Olga
The arrangement has two disadvantages: the necessity to monitor composition of the two outlet gas streams, which requires analytical instruments and the strict requirement of equal pressure in both compartments. On the other hand measurement could be carry out in raised temperature and/or pressure. GrahamŽs diffusion cell is based on validity of GrahamŽs law. This cell overcomes both disadvantages of the classic Wicke-Kallenbach cell.
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