Effect of Interlayer Ions on Methane Hydrate Formation in Clay Sediments

Abstract

Natural methane hydrates occurring in marine clay sediments exhibit heterogeneous phase behavior with high complexity, particularly in the negatively charged interlayer region. To date, the real clay interlayer effect on natural methane hydrate formation and stability remains still much unanswered, even though a few computer simulation and model studies are reported. We first examined the chemical shift difference of 27Al, 29Si, and 23Na between dry clay and clay containing intercalated methane hydrates (MH) in the interlayer. We also measured the solid-state 13C MAS NMR spectra of MH in Na-montmorillonite (MMT) and Ca-montmorillonite (MMT) to reveal abnormal methane popularity established in the course of intercalation and further performed cryo-TEM and XRD analyses to identify the morphology and layered structure of the intercalated methane hydrate. The present findings strongly suggest that the real methane amount contained in natural MH deposits should be reevaluated under consideration of the compositional, structural, and physical characteristics of clay-rich sediments. Furthermore, the intercalated methane hydrate structure should be seriously considered for developing the in situ production technologies of the deep-ocean methane hydrate.

Methane Hydrate in Confined Spaces: An Alternative Storage System

“…X‐ray powder diffraction has been widely used to identify the crystal structure and the cell parameters of natural, synthetic and confined methane hydrates as well as in their single crystal . In principle, single crystal structure analysis is one of the most reliable methods to obtain crystal structure data, however, it has never been applied for the crystals inside confining pores.…”

Applications of nuclear shielding

“…195 The chemical shift difference of 27 Al, 29 Si and 23 Na between dry clay and clay containing intercalated methane hydrates (MH) in the interlayer was examined. 196 71 Ga, 69 Ga and 115 In isotopes were studied by NMR (NMR) in liquid gallium-indium alloy confined to porous glass and alloy surface film and were compared with the bulk counterparts. Drastic spin relaxation acceleration under nanoconfinement was observed for the three isotopes.…”

“…It was examined the chemical shift difference of 29 Si between dry clay and clay containing intercalated methane hydrates (MH) in the interlayer. 278 2.14.3 Tin ( 117,119 Sn) (I = 1/2, 1/2). D(CH 2 CH 2 S) 2 MSNH(C 6 H 4 ) (M = Ge, Sn; D = O, S) spirocycles were synthesised to analyse the influence of the decrease of the radius of the metal and the change of the hardness of donor atom on the strength of the transannular bond and the hypercoordination of group 14 elements.…”

Investigation on methane hydrate formation in silica gel particles below the freezing point

“…Another large-scale natural gas storage method that stores natural gas as the hydrate has recently been gaining signicant attention. 9 Takeya et al [10][11][12][13][14] have found that the methane hydrate could be preserved for one week at 248 K and 0.1 MPa because of the ice sheet formed around the methane hydrate particles. So the preservation time is longer than that of LNG at 248 K and 0.1 MPa.…”

“…Finally, an increasing number of works have concentrated on how to enhance the rate of natural gas hydrate formation, which is essential to practically make use of NGH. 13,14 Mandal et al 15,16 studied the effect of anionic surfactant on methane hydrate formation. It was found that even though the anionic surfactant could improve the gas uptake, the maximum water conversion to hydrate was only 15.91% and the magnetic stirrer consumed a large amount of energy.…”