Possibilities of determining the polymodal pore-size distribution from physical adsorption of nitrogen

1987 ◽  
Vol 52 (5) ◽  
pp. 1160-1166
Author(s):  
Dagmar Tomanová ◽  
Petr Schneider
Keyword(s):  
Pore Size ◽  
Size Distribution ◽  
Physical Adsorption ◽  
Relative Pressure ◽  
Size Distributions ◽  
Porous Sample ◽  
Fine Grained ◽  
Mesopore Size Distribution ◽  
Pore Size Distributions ◽  
Adsorption Of Nitrogen

It is shown, on the basis of experimentally determined adsorption isotherms of physical adsorption of nitrogen on two- and three-component mixtures of fine grained porous glasses with narrow pore-size distributions, that the polymodal mesopore-size distribution curves can be evaluated in case that the porous sample contains groups of mesopores differing rather significantly in size. The differentiation of groups of pores gets worse with wider pores where the demands on the accuracy of the relative pressure measurement grow stronger.

Two sides of the same inverse problem, in identifying the pore size distribution based on experiments with non-Newtonian fluids

2021 ◽  
Author(s):  
Martin Lanzendörfer
Keyword(s):  
Inverse Problem ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Forward Problem ◽  
Size Distributions ◽  
Pore Sizes ◽  
Pore Size Distributions ◽  
Flow Through ◽  
Effective Pore Size

<p>Following the capillary bundle concept, i.e. idealizing the flow in a saturated porous media in a given direction as the Hagen-Poiseuille flow through a number of tubular capillaries, one can very easily solve what we would call the <em>forward problem</em>: Given the number and geometry of the capillaries (in particular, given the pore size distribution), the rheology of the fluid and the hydraulic gradient, to determine the resulting flux. With a Newtonian fluid, the flux would follow the linear Darcy law and the porous media would then be represented by one constant only (the permeability), while materials with very different pore size distributions can have identical permeability. With a non-Newtonian fluid, however, the flux resulting from the forward problem (while still easy to solve) depends in a more complicated nonlinear way upon the pore sizes. This has allowed researchers to try to solve the much more complicated <em>inverse problem</em>: Given the fluxes corresponding to a set of non-Newtonian rheologies and/or hydraulic gradients, to identify the geometry of the capillaries (say, the effective pore size distribution).</p><p>The potential applications are many. However, the inverse problem is, as they usually are, much more complicated. We will try to comment on some of the challenges that hinder our way forward. Some sets of experimental data may not reveal any information about the pore sizes. Some data may lead to numerically ill-posed problems. Different effective pore size distributions correspond to the same data set. Some resulting pore sizes may be misleading. We do not know how the measurement error affects the inverse problem results. How to plan an optimal set of experiments? Not speaking about the important question, how are the observed effective pore sizes related to other notions of pore size distribution.</p><p>All of the above issues can be addressed (at least initially) with artificial data, obtained e.g. by solving the forward problem numerically or by computing the flow through other idealized pore geometries. Apart from illustrating the above issues, we focus on <em>two distinct aspects of the inverse problem</em>, that should be regarded separately. First: given the forward problem with <em>N</em> distinct pore sizes, how do different algorithms and/or different sets of experiments perform in identifying them? Second: given the forward problem with a smooth continuous pore size distribution (or, with the number of pore sizes greater than <em>N</em>), how should an optimal representation by <em>N</em> effective pore sizes be defined, regardless of the method necessary to find them?</p>

Yield Stress Fluid Method to Measure the Pore Size Distribution of a Porous Medium

2010 ◽  
Author(s):  
Aimad Oukhlef ◽  
Abdlehak Ambari ◽  
Ste´phane Champmartin ◽  
Antoine Despeyroux
Keyword(s):  
Porous Media ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Size Distributions ◽  
First Approximation ◽  
Pore Size Distributions ◽  
Plastic Fluid ◽  
Present Technique ◽  
Mathematical Processing

In this paper a new method is presented in order to determine the pore size distribution in a porous media. This original technique uses the non Newtonian yield-pseudo-plastic rheological properties of some fluid flowing through the porous sample. In a first approximation, the very well-known and simple Carman-Kozeny model for porous media is considered. However, despite the use of such a huge simplification, the analysis of the geometry still remains an interesting problem. Then, the pore size distribution can be obtained from the measurement of the total flow rate as a function of the imposed pressure gradient. Using some yield-pseudo-plastic fluid, the mathematical processing of experimental data should give an insight of the pore-size distribution of the studied porous material. The present technique was successfully tested analytically and numerically for classical pore size distributions such as the Gaussian and the bimodal distributions using Bingham or Casson fluids (the technique was also successfully extended to Herschel-Bulkley fluids but the results are not presented in this paper). The simplicity and the cheapness of this method are also its assets.

scholarly journals Fractal Characteristics of Micro- and Mesopores in the Longmaxi Shale

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1349
Author(s):  
Xiaoqi Wang ◽  
Yanming Zhu ◽  
Yang Wang
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Co2 Adsorption ◽  
Controlling Factors ◽  
Size Distributions ◽  
Pore Size Distributions ◽  
Longmaxi Shale ◽  
Fractal Characteristics ◽  
Multifractal Behavior

To better understand the variability and heterogeneity of pore size distributions (PSDs) in the Longmaxi Shale, twelve shale samples were collected from the Xiaoxi and Fendong section, Sichuan Province, South China. Multifractal analysis was employed to study PSDs of mesopores (2–50 nm) and micropores (<2 nm) based on low-pressure N2/CO2 adsorption (LP-N2/CO2GA). The results show that the PSDs of mesopores and micropores exhibit a multifractal behavior. The multifractal parameters can be divided into the parameters of heterogeneity (D−10–D10, D0–D10 and D−10–D0) and the parameters of singularity (D1 and H). For both the mesopores and micropores, decreasing the singularity of the pore size distribution contributes to larger heterogeneous parameters. However, micropores and mesopores also vary widely in terms of the pore heterogeneity and its controlling factors. Shale with a higher total organic carbon (TOC) content may have a larger volume of micropores and more heterogeneous mesopores. Rough surface and less concentrated pore size distribution hinder the transport of adsorbent in mesopores. The transport properties of micropores are not affected by the pore fractal dimension.

scholarly journals The Pore Size Distribution of Naturally Porous Cigarette Paper and its Relation to Permeability and Diffusion Capacity

2015 ◽  
Vol 26 (7) ◽  
Author(s):  
Bernhard Eitzinger ◽  
Maria Gleinser ◽  
Stefan Bachmann
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Filler Content ◽  
Air Permeability ◽  
Size Distributions ◽  
Diffusion Capacity ◽  
Pore Size Distributions ◽  
Cigarette Paper ◽  
And Diffusion

SummaryThe pore size distribution of cigarette paper determines its air permeability and diffusion capacity and thereby has a significant influence on the gas exchange of a cigarette through the cigarette paper during smoking and during smouldering. For the design of cigarettes and in particular of cigarette papers it is important to understand how the pore size distribution of the cigarette paper is affected by the paper composition and paper properties and how it influences air permeability and diffusion capacity.It was the aim of this study to investigate how the composition of the cigarette paper such as filler content, fibre type and burn additive content qualitatively influenced the pore size distribution and how the pore size distribution and, in particular, which pore size range is correlated with air permeability and diffusion capacity, respectively. To this end eight naturally porous cigarette papers were selected which differed in air permeability, diffusion capacity, fibre type, filler content and burn additive content. The pore size distributions of these papers were measured by mercury porosimetry before and after the papers had been heated to 230 °C for 30 min. The pore size distributions were investigated for qualitative differences when air permeability, fibre type and filler content of the cigarette paper are modified. Furthermore by appropriate weighting of the pore size distributions optimal correlations between a weighted pore volume and air permeability or diffusion capacity were determined. The results show a good correlation with correlation coefficients greater than 0.9 for air permeability as well as for diffusion capacity. The results indicate that large pores are better correlated with changes in air permeability, while small pores are more strongly correlated with changes in diffusion capacity and support previous theoretical results obtained from flow and diffusion models. They also demonstrate the tight relationship between pore size distribution, air permeability and diffusion capacity, which makes the pore size distribution a tool to further optimize cigarette papers, for example, with respect to carbon monoxide yields in the smoke of a cigarette. [Beitr. Tabakforsch. Int 26 (2015) 312-319]

scholarly journals Porogen Effect of Solvents on Pore Size Distribution of Solvent-Casted Polycaprolactone Thin Films

2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Fariba Safaei ◽  
Shahla Khalili ◽  
Saied Nouri Khorasani ◽  
Laleh Ghasemi-Mobarakeh ◽  
Rasoul Esmaeely Neisiany
Keyword(s):  
Thin Films ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Methylene Chloride ◽  
Size Distributions ◽  
Solvent Casting ◽  
Casting Method ◽  
Effect Of Solvents ◽  
Pore Size Distributions

In this study, the effect of porogenic solvents on pore size distribution of the polycaprolactone (PCL) thin films was investigated. Five thin PCL films were prepared using the solvent-casting method. Chloroform, Methylene Chloride (MC) and three different compositions of MC/ Dimethylformamide (DMF) (80/20, 50/50 and 20/80) were used as solvents. Scanning Electron Microscopy (SEM) investigations were employed to study morphology and consequently the pore size distribution of the prepared films. The PCL films made by chloroform and MC as a solvent were completely non-porous. Whereas the other films (made by a combination of MC and DMF) showed both uni-modal and bi-modal pore size distributions.

scholarly journals Modelling of shale rock pore structure based on gas adsorption

2019 ◽  
Vol 92 ◽  
pp. 15006
Author(s):  
Arghya Das ◽  
Sumit Basu ◽  
Ankit Kumar
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Gas Flow ◽  
Gas Adsorption ◽  
Knudsen Diffusion ◽  
Pore Network Model ◽  
Size Distributions ◽  
Shale Rock ◽  
Pore Size Distributions

Shale rock consists of a complex matrix structure due to presence of nano-scale pores. Owing to such complexity determination and/or prediction of the mineralogical, mechanical, and petrophysical properties (e.g., permeability, porosity, pore size distribution, etc.) of shale is a challenging task. A preliminary estimation of these properties is essential before shale gas exploration. In this study, experimental and numerical analyses are conducted to estimate the permeability, porosity, and pore size distribution of a typical shale sample. Gas adsorption experiments were conducted to characterize the pore spaces of the shale via analysing the isotherms. Using conventional theories, such as BET and BJH methods, surface area, pore volume, and pore size distributions were estimated. On the other hand, gross porosity of the shale samples was measured by conducting gas pycnometry experiment. Finally based on the obtained results an equivalent pore network model is constructed which accounts for the pore size distributions and low pore connectivity in the shale matrix. We have simulated gas flow through the network to estimate permeability of the shale. This model considers Knudsen diffusion and the effects of gas slippage on permeability. Further parametric study shows that the apparent permeability primarily depends on the reservoir pressure, pore coordination number and porosity.

Sintering polydispersed spherical glass particles

2003 ◽  
Vol 18 (6) ◽  
pp. 1347-1354 ◽  
Author(s):  
Miguel O. Prado ◽  
Edgar D. Zanotto ◽  
Catia Fredericci
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Cross Sections ◽  
Soda Lime ◽  
Size Distributions ◽  
Glass Spheres ◽  
Pore Size Distributions ◽  
Soda Lime Silica Glass ◽  
First Time

We used the Clusters model to study the densification kinetics and resulting porosity of a compact of polydispersed soda-;lime-;silica glass spheres. In addition to the physical data (viscosity, surface tension, particle size distribution) required by the Clusters model, for the first time in glass-;sintering studies, we took extra variables into account: the average number of necks per sphere, the effects of pre-;existing crystals on the particle surfaces, and sample size. The model predicted both the densification kinetics and the resulting pore-;size distribution of sintered compacts. A cross section of a porous sample displayed a porosity pattern that agreed with computer-;simulated cross sections, whose pore-;size distributions was calculated via the Clusters model using a Monte Carlo technique. Its capacity to predict both density and pore-;size distribution makes the Clusters model a valuable tool for designing sintered glasses with any desired microstructure.

Physical adsorption of gases on porous solids - II. Calculation of pore-size distributions

1951 ◽  
Vol 209 (1096) ◽  
pp. 69-81 ◽  
Keyword(s):  
Pore Size ◽  
Capillary Condensation ◽  
Physical Adsorption ◽  
Large Fraction ◽  
Particle Surface ◽  
Porous Solids ◽  
Size Distributions ◽  
Pore Size Distributions ◽  
Total Particle ◽  
Accessible Surface

When capillary condensation takes place, it is accompanied by multilayer adsorption in empty capillaries. To apply the Kelvin equation to pore-size distributions, it is necessary to make allowance for multilayers, and a method of carrying this out is presented. Any such calculation requires either an estimated or experimental adsorption isotherm for the same surface when capillary condensation is absent. In this paper, it was possible to apply it to the data of part I, in which adsorption isotherms were compared for loose powders and for the same powders compressed into porous plugs. Modification of the calculation when capillaries fill by blockage instead of condensation is discussed. Blockage can prevail over capillary condensation only in pores with radii < 8 to 10 Å, and even then only if heats of adsorption are high, so that a large fraction of the surface is covered at low relative pressures. Owing to presence of adsorbed layers, the Kelvin radius is less than the true pore radius, but it is difficult to decide upon the proper correction, and much uncertainty results for radii < 30 Å. Pore-size distribution curves were derived and compared for plugs of varying porosity. They provided strong evidence of tightly packed aggregates of particles, and of an increasing uniformity of pore size as porosity is decreased. In Carbolac 1 plugs of low porosity, a few pores with radii only a little larger than the radius of a CF 2 CI 2 molecule were encountered, but no pores were smaller. This agrees with the observa­tion that the total particle surface was initially accessible to CF 2 CI 2 molecules, but that a rapid decrease of accessible surface took place before even a complete monolayer had been adsorbed.

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