Preponderant Occurrence of sl natural methane hydrates: Spectroscopic analysis of crystalline structure transition

sI 천연 메탄하이드레이드의 존재 : 결정구조 변화의 분광학적 분석

  • 연순화 (한국과학기술연구원) ;
  • 설지웅 (한국과학기술연구원) ;
  • 이흔 (한국과학기술연구원)
  • Published : 2006.06.22

Abstract

We report here that under strong attacksof external $CH_4$ guest molecules the sII and sH methane hydrates are structurally transformed to the crystalline me framework of sI, leading to favorable change of the lattice dimension of the host-guest networks. The High Power Decoupling $^{13}C$ NMR and Raman spectroscopies were used to identify structure transitions of the mixed $CH_4+C_2H_6$ hydrates (sIIl) and hydrocarbons (methylcyclohexane, isopentane) + $CH_4$ hydrates (sH). The resulting spectra indicate that most of the synthesized sII and sH hydrates were transformed to methane hydrate of sl under 110 bar and particularly the coexistence of sl with sII or sH appear according to the surrounding methane-rich gas conditions. The present findings might be expected to Provide rational evidences regarding the preponderant occurrence of naturally-occurring sI methane hydrates in marine sediments.