Argon adsorption on MCM-41 mesoporous crystal studied by in situ synchrotron powder X-ray diffraction

Norihiro Muroyama, Arisa Yoshimura, Yoshiki Kubota, Keiichi Miyasaka, Tetsu Ohsuna, Ryong Ryoo, Peter I. Ravikovitch, Alexander V. Neimark, Masaki Takata, Osamu Terasaki

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56 Citations (Scopus)


Equilibrium argon adsorption from the gas phase on mesoporous MCM-41 silica of hexagonal structure is directly studied by in situ synchrotron powder X-ray diffraction (XRD) measurements at SPring-8. The diffraction intensity data is analyzed by extending the previously developed analytical formula for the crystal structure factors of MCM-41 to account for argon adsorbed in the pores. It is clearly observed that argon adsorbs in layers on the pore walls at low gas pressures and exhibits sudden capillary condensation as the gas pressure increased. The proposed method of interpretation of XRD data allows one to calculate the density ratio between the silica wall and condensed argon, the pore size, and the pore wall fluctuation/roughness, together with the thickness of the adsorbed layer as a function of the gas pressure. The results of in situ XRD experiments are compared with the results of argon adsorption volumetric experiments. The adsorption data are interpreted with the quench solid density functional theory (QSDFT), which takes into account the pore wall roughness. The perfect agreement of the QSDFT isotherm predicted from the adsorption data and the XRD recalculated isotherm suggests that the adsorption porosimetry and XRD measurements can be reconciled provided a proper interpretation of the experimental data.

Original languageEnglish
Pages (from-to)10803-10813
Number of pages11
JournalJournal of Physical Chemistry C
Issue number29
Publication statusPublished - 2008 Jul 24
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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