title: Spectroscopic Observation of the Hydroxy Position in Butanol Hydrates and Its Effect on Hydrate Stability.
abstract: In this study, we investigate the crystal structures and phase equilibria of butanols+CH4+H2O systems to reveal the hydroxy group positioning and its effects on hydrate stability. Four clathrate hydrates formed by structural butanol isomers are identified with powder X-ray diffraction (PXRD). In addition, Raman spectroscopy is used to analyze the guest distributions and inclusion behaviors of large alcohol molecules in these hydrate systems. The existence of a free OH indicates that guest molecules can be captured in the large cages of structure II hydrates without any hydrogen-bonding interactions between the hydroxy group of the guests and the water-host framework. However, Raman spectra of the binary (1-butanol+CH4) hydrate do not show the free OH signal, indicating that there could be possible hydrogen-bonding interactions between the guests and hosts. We also measure the four-phase equilibrium conditions of the butanols+CH4+H2O systems.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Republic of Korea).
authors.forename: Yeobum
authors.initials: Y
authors.lastname: Youn
authors.affiliation: Department of Energy and Resources Engineering, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon-si, Gangwon-do, 200-701 (Republic of Korea).
authors.forename: Minjun
authors.initials: M
authors.lastname: Cha
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Republic of Korea).
authors.forename: Huen
authors.initials: H
authors.lastname: Lee
keywords: Raman spectroscopy; X-ray diffraction; butanol; hydrates; phase equilibria