Spectroscopic identification, thermodynamic stability and molecular composition of hydrogen and 1,4-dioxane binary clathrate hydrate

We present the spectroscopic identification of the binary hydrogen and 1,4-dioxane clathrate hydrates in which H2 molecules are encapsulated in small cages of the structure II hydrate framework. X-ray diffraction, solid-state NMR and Raman spectroscopy were used to confirm the mixed hydrate structure and more importantly the occupancy pattern of hydrogen in clathrate cages. The corresponding pressure–temperature behavior and direct gas release measurements were also determined to support the spectroscopic results. The direct volumetric measurements revealed that the favorable confinement of hydrogen molecules over 0.4wt% could be obtained by the compositional tuning of the binary products. r 2007 Elsevier Ltd. All rights reserved.