Distortion of the Large Cages Encapsulating Cyclic Molecules and Empty Small Cages of Structure II Clathrate Hydrates

Satoshi Takeya, Saman Alavi, Shunsuke Hashimoto, Keita Yasuda, Yuji Yamauchi, Ryo Ohmura

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Understandings of structure-based properties of porous materials, such as gas storage and gas separation performance, are important. Here, the crystal structures of the canonical structure II (sII) clathrate hydrates encapsulating cyclic molecules (tetrahydrofuran, cyclopentane, furan, and tetrahydropyran) are studied. To understand the effect of guest molecules on the host water framework, we performed powder X-ray diffraction measurements where the hydrate structures and guest distribution within 51264 cages were obtained by the direct-space technique followed by the Rietveld refinement. It was shown that the sizes of the 512 and 51264 cages of sII hydrates expand, as its unit-cell size is enlarged by the guest. In this process, it is revealed that the shape of 51264 cages with larger guest molecules became more spherical and volume ratio of empty small 512 cages in the unit cell decreases. Our findings from crystallographic point of view may give insights into better understanding of the thermodynamic stability and higher gas storage capacity of binary clathrate hydrates.

Original languageEnglish
Pages (from-to)18134-18141
Number of pages8
JournalJournal of Physical Chemistry C
Volume122
Issue number31
DOIs
Publication statusPublished - 2018 Aug 9

ASJC Scopus subject areas

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

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