Pore-size distributions from nitrogen adsorption revisited: Models comparison with controlled-pore glasses

Šolcová, Olga; Matějová, Lenka; Schneider, P.

doi:10.1016/j.apcata.2006.07.021

Cited by 25 publications

(22 citation statements)

References 24 publications

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“…where t is the thickness of the adsorbed layer on the pore wall (Å), p the partial pressure of N 2 , and p 0 the saturation pressure of N 2 at 77 K (14).…”

Section: Methodsmentioning

confidence: 99%

“…Introduction of the statistical film thickness (t thickness) that accounts for the formation of the liquidlike layer on the pore wall prior to commencement of capillary condensation was shown to more accurately represent experimental data. A universal dependence of the t thickness on the partial pressure of nitrogen was found for various adsorbate surface types (14,15). de Boer et al conducted an extensive study of the t-curve method for various porous materials (15)(16)(17)(18)(19)(20)(21) and determined the actual pore radius to be the sum of the radius calculated by the Kelvin equation and the thickness of the adsorbed t layer at each given partial pressure.…”

Section: Introductionmentioning

confidence: 99%

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On the Micro-, Meso-, and Macroporous Structures of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers

Soboleva

Zhao

Malek

et al. 2010

ACS Appl. Mater. Interfaces

345

309

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In this work, N 2 adsorption was employed to investigate the effects of carbon support, platinum, and ionomer loading on the microstructure of polymer electrolyte membrane fuel cell catalyst layers (CLs). Brunauer-Emmett-Teller and t-plot analyses of adsorption isotherms and pore-size distributions were used to study the microstructure of carbon supports, platinum/carbon catalyst powders, and three-component platinum/carbon/ionomer CLs. Two types of carbon supports were chosen for the investigation: Ketjen Black and Vulcan XC-72. CLs with a range of Nafion ionomer loadings were studied in order to evaluate the effect of an ionomer on the CL microstructure. Regions of adsorption were differentiated into micropores associated with the carbon primary particles (<2 nm), mesopores ascribed to the void space inside agglomerates (2-20 nm), and meso-to macroporous space inside aggregates of agglomerates (>50 nm). Ketjen Black was found to possess a significant fraction of micropores, 25% of the total pore volume, in contrast to Vulcan XC-72, for which the corresponding fraction of micropores was 15% of the total pore volume. The microstructure of the carbon support was found to be a significant factor in the formation of the microstructure in the three-component CLs, serving as a rigid porous framework for distribution of platinum and the ionomer. It was found that platinum particle deposition on Ketjen Black occurs in, or at the mouth of, the support's micropores, thus affecting its effective microporosity, whereas platinum deposition on Vulcan XC-72 did not significantly affect the support's microstructure. The codeposition of ionomer in the CL strongly influenced its porosity, covering pores < 20 nm, which are ascribed to the pores within the primary carbon particles (pore sizes < 2 nm) and to the pores within agglomerates of the particles (pore sizes of 2-20 nm).

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“…where t is the thickness of the adsorbed layer on the pore wall (Å), p the partial pressure of N 2 , and p 0 the saturation pressure of N 2 at 77 K (14).…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the Micro-, Meso-, and Macroporous Structures of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers

Soboleva

Zhao

Malek

et al. 2010

ACS Appl. Mater. Interfaces

345

309

View full text Add to dashboard Cite

show abstract

“…Fig. 6 depicts three total isotherms for different CPG adsorbents and the corresponding actual pore size distributions measured via mercury porosimetry and borrowed from Solcova et al [13]. Table 4 presents all intermediate results and final values using the iterative method with no unrealistic assumptions.…”

Section: Application Of Iterative Methods For Real Case Studiesmentioning

confidence: 99%

“…In this section, three real case studies (i.e., experimental total isotherms borrowed from literature [13]) are used along with the corresponding measured (actual) pore size distributions to demonstrate the reliable performance of our iterative algorithm. The following comparative study focuses on comparison of the newly proposed method with the conventional procedure for evaluation of local adsorption isotherm parameters from experimental nitrogen physical adsorption isotherms (at 77 K) measured on a series of controlled-pore glasses (CPG) with wide range of nominal pore sizes.…”

Section: Application Of Iterative Methods For Real Case Studiesmentioning

confidence: 99%

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Reliable estimation of adsorption isotherm parameters using adequate pore size distribution

Husseinzadeh

Shahsavand

2015

Korean J. Chem. Eng.

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The equilibrium adsorption isotherm has a crucial effect on various characteristics of the solid adsorbent (e.g., pore volume, bulk density, surface area, pore geometry). A historical paradox exists in conventional estimation of adsorption isotherm parameters. Traditionally, the total amount of adsorb material (total adsorption isotherm) has been considered equivalent to the local adsorption isotherm. This assumption is only valid when the corresponding pore size or energy distribution (PSD or ED) of the porous adsorbent can be successfully represented with the Dirac delta function. In practice, the actual PSD (or ED) is far from such assumption, and the traditional method for prediction of local adsorption isotherm parameters leads to serious errors. Up to now, the powerful combination of inverse theory and linear regularization technique has drastically failed when used for extraction of PSD from real adsorption data. For this reason, all previous researches used synthetic data because they were not able to extract proper PSD from the measured total adsorption isotherm with unrealistic parameters of local adsorption isotherm. We propose a novel approach that can successfully provide the correct values of local adsorption isotherm parameters without any a priori and unrealistic assumptions. Two distinct methods are suggested and several illustrative (synthetic and real experimental) examples are presented to clearly demonstrate the effectiveness of the newly proposed methods on computing the correct values of local adsorption isotherm parameters. The so-called Iterative and Optima methods' impressive performances on extraction of correct PSD are validated using several experimental data sets.

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Production of activated carbon by H₃PO₄ activation treatment of corncob and its performance in removing nitrobenzene from water

et al. 2007

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Activated carbon was produced by fast precarbonization of corncobs in a fluidized bed followed by H 3 PO 4 activation. The results showed that the product is essentially microporous carbon whose BET surface area and pore volume when the carbon was activated at 9008C were 1588 m 2 /g and 0.8163 mL/g, respectively. The experimental operating conditions were as follows: carbonizing the corncobs in the preheated fluidized-bed at 3508C for 5 min using N 2 as carrier gas; impregnating the char with H 3 PO 4 with an impregnation ratio of 1:5 (Char/H 3 PO 4 ); and activating the mixture at 9008C for 30 min in the tubular furnace. The potential usefulness of the resultant carbons for removal of nitrobenzene from water was also investigated.

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Pore-size distributions from nitrogen adsorption revisited: Models comparison with controlled-pore glasses

Cited by 25 publications

References 24 publications

On the Micro-, Meso-, and Macroporous Structures of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers

On the Micro-, Meso-, and Macroporous Structures of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers

Reliable estimation of adsorption isotherm parameters using adequate pore size distribution

Production of activated carbon by H₃PO₄ activation treatment of corncob and its performance in removing nitrobenzene from water

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Pore-size distributions from nitrogen adsorption revisited: Models comparison with controlled-pore glasses

Cited by 25 publications

References 24 publications

On the Micro-, Meso-, and Macroporous Structures of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers

On the Micro-, Meso-, and Macroporous Structures of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers

Reliable estimation of adsorption isotherm parameters using adequate pore size distribution

Production of activated carbon by H3PO4 activation treatment of corncob and its performance in removing nitrobenzene from water

Contact Info

Product

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About

Production of activated carbon by H₃PO₄ activation treatment of corncob and its performance in removing nitrobenzene from water