Crystal lattice size and stability of type H clathrate hydrates with various large-molecule guest substances

Satoshi Takeya, Akira Hori, Tsutomu Uchida, Ryo Ohmura

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

To gain a better understanding of the effects of guest molecules on the lattice and stability of type H hydrates, we performed powder X-ray diffraction (PXRD) measurements and semiempirical molecular orbital calculations. The unit cell parameters and cohesive energies of various type H hydrates that contain methane (CH4) were analyzed. PXRD measurements indicated that an increase in the large-molecule guest volume caused the unit cell volume to increase. It was also indicated that a large-molecule guest substance caused the a-axis-direction of the unit cell to increase with little decrease in the c-axis direction. Calculations of cohesive energy by means of a semiempirical molecular orbital method indicated that the functional group and configuration of large-molecule guest substances affects the stability of type H hydrates. It was concluded that the icosahedron (51268) cages do not easily increase in length along the c-axis direction when larger guest molecules are used to form the hydrate, but the 51268 cage and the layer of dodecahedron (512) cages can easily increase in length along the a-axis direction due to interactions of the guest-host molecule.

Original languageEnglish
Pages (from-to)12943-12947
Number of pages5
JournalJournal of Physical Chemistry B
Volume110
Issue number26
DOIs
Publication statusPublished - 2006 Jul 6

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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