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Title: Microstructural Characterization of Adsorption and Depletion Regimes of Supercritical Fluids in Nanopores

Abstract

Fluid accommodation in porous media has been studied over a wide range of pressures at three supercritical temperatures by small-angle neutron scattering. A new formalism gives for the first time the mean density and volume of the adsorbed fluid phase formed in the pores from experimental data; thus, excess, absolute, and total adsorption become measurable quantities without the introduction of further assumptions. Results on propane adsorption to a silica aerogel show the formation of a thin adsorption layer of high density at low bulk fluid pressures and densities. In that region, the density of the adsorption layer increases with increasing fluid density while its volume remains approximately constant. Depletion of the fluid from the pore space is found near and above the critical density, which leads to negative values of the excess adsorption. At high fluid densities, the pores are evenly filled with fluid of lower density than the bulk fluid. The total amount of fluid confined in the pore spaces increases with the fluid density below the critical density and remains approximately constant at higher fluid densities. Application of the new model also gives insight into the sorption properties of supercritical carbon dioxide in silican aerogel. The concept presentedmore » here has potential to be adopted for the study of numerous other sub- and supercritical fluids and fluid mixtures in a variety of micro- and nanoporous materials.« less

Authors:
 [1];  [1];  [1];  [2];  [1]
  1. ORNL
  2. Forschungszentrum Julich, Julich, Germany
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
930826
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry C; Journal Volume: 111; Journal Issue: 43
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ADSORPTION; CARBON DIOXIDE; MIXTURES; NEUTRONS; PROPANE; SCATTERING; SILICA; SORPTION

Citation Formats

Rother, Gernot, Melnichenko, Yuri B, Cole, David R, Frielinghaus, H., and Wignall, George D. Microstructural Characterization of Adsorption and Depletion Regimes of Supercritical Fluids in Nanopores. United States: N. p., 2007. Web. doi:10.1021/jp073698c.
Rother, Gernot, Melnichenko, Yuri B, Cole, David R, Frielinghaus, H., & Wignall, George D. Microstructural Characterization of Adsorption and Depletion Regimes of Supercritical Fluids in Nanopores. United States. doi:10.1021/jp073698c.
Rother, Gernot, Melnichenko, Yuri B, Cole, David R, Frielinghaus, H., and Wignall, George D. Mon . "Microstructural Characterization of Adsorption and Depletion Regimes of Supercritical Fluids in Nanopores". United States. doi:10.1021/jp073698c.
@article{osti_930826,
title = {Microstructural Characterization of Adsorption and Depletion Regimes of Supercritical Fluids in Nanopores},
author = {Rother, Gernot and Melnichenko, Yuri B and Cole, David R and Frielinghaus, H. and Wignall, George D},
abstractNote = {Fluid accommodation in porous media has been studied over a wide range of pressures at three supercritical temperatures by small-angle neutron scattering. A new formalism gives for the first time the mean density and volume of the adsorbed fluid phase formed in the pores from experimental data; thus, excess, absolute, and total adsorption become measurable quantities without the introduction of further assumptions. Results on propane adsorption to a silica aerogel show the formation of a thin adsorption layer of high density at low bulk fluid pressures and densities. In that region, the density of the adsorption layer increases with increasing fluid density while its volume remains approximately constant. Depletion of the fluid from the pore space is found near and above the critical density, which leads to negative values of the excess adsorption. At high fluid densities, the pores are evenly filled with fluid of lower density than the bulk fluid. The total amount of fluid confined in the pore spaces increases with the fluid density below the critical density and remains approximately constant at higher fluid densities. Application of the new model also gives insight into the sorption properties of supercritical carbon dioxide in silican aerogel. The concept presented here has potential to be adopted for the study of numerous other sub- and supercritical fluids and fluid mixtures in a variety of micro- and nanoporous materials.},
doi = {10.1021/jp073698c},
journal = {Journal of Physical Chemistry C},
number = 43,
volume = 111,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}