Decomposition kinetics and recycle of binary hydrogen‐tetrahydrofuran clathrate hydrate

Abstract

Decomposition kinetics and recycle of hydrogen-tetrahydrofuran (H 2 -THF) clathrate hydrates were investigated with a pressure decay method at temperatures from 265.1 to 273.2 K, at initial pressures from 3.1 to 8.0 MPa, and at stoichiometric THF hydrate concentrations for particle sizes between 250 and 1000 lm. The decomposition was modeled as a two-step process consisting of H 2 diffusion in the hydrate phase and desorption from the hydrate cage. The adsorption process occurred at roughly two to three times faster than the desorption process, whereas the diffusion process during formation was slightly higher (ca. 20%) than that during decomposition. Successive formation and decomposition cycles showed that occupancy seemed to decrease only slightly with cycling and that there were no large changes in hydrate structure due to cycling. Results provide evidence that the formation and decomposition of H 2 clathrate hydrates occur reversibly and that H 2 clathrate hydrates can be recycled with pressure.

Low barriers for hydrogen diffusion in sII clathrate

“…Florusse et al 3 showed that the inclusion of tetrahydrofuran (THF) as a promoter molecule allowed such hydrates to form at ambient conditions. NMR studies 5 and decomposition studies 6 with THF have produced diffusion barriers as low as 3 kJ mol À1 , but this contrasts the rather large barriers found by molecular simulations. Lee et al 4 found that this cost could be tuned by varying the content of THF.…”

“…In order for the hydrate to be usable as a storage medium, low barriers for gas diffusion are required. NMR studies 5 and decomposition studies 6 with THF have produced diffusion barriers as low as 3 kJ mol À1 , but this contrasts the rather large barriers found by molecular simulations. 7,8 The purpose of this paper is to investigate this discrepancy.…”

A database approach for materials selection for hydrogen storage in aerospace technology

“…The last two stabilizing agents yield relatively high hydrogen storage capacities (1.35 and 1.42 wt%, respectively). Another very well studied and promising promoter for hydrogen clathrate stabilization is tetrahydrofuran (THF), whose addition drastically decreases the formation pressure (Kawamura et al 2011;Prasad et al 2009;Lee et al 2005;Veluswamy and Linga 2013;Nagai et al 2008;Ogata et al 2008;Yoshioka et al 2011;Arca et al 2008). The hydrogen storage capacities in THF-containing binaryclathrate hydrates can be increased up to 4.03 wt% at modest pressures by tuning their composition to allow the hydrogen guests to enter both the larger and the smaller cages, while retaining low-pressure stability.…”

Methane and hydrogen storage in clathrate hydrates

“…However, contrasting views exist among researchers, with some disputing the influence of THF concentration on H2 storage and failing to replicate comparable storage capacities through tuning [277,286,287]. While tetrahydrofuran (THF) has been extensively studied as a promoter for sII H2 hydrate formation [288][289][290][291][292][293][294][295][296][297][298][299][300][301][302][303][304], there is a growing interest in exploring alternative promoters such as dioxolane (DIOX), epoxy(cyclopentane), cyclohexanone, 1,4-dioxane (DXN), tetrahydropyran, and 2,5-dihydrofuran [293,295,300,[305][306][307][308][309][310][311][312][313]. These promoters are being investigated for their potential to enhance thermodynamics, improve hydrate stability, and increase H2 storage capacity.…”

“…To improve the kinetics of binary H2/THF hydrates, Veluswamy et al [295] utilized a stirred tank reactor (STR) and achieved a maximum H2 storage capacity of 0.19 wt.% within 6 hours at 13.3 MPa and 279.2 K. Other researchers also conducted similar experiments using STR to enhance the kinetics of hydrate formation, as summarized in Table 1.10. Other studies aimed to enhance H2 mass diffusion by exposing high-pressure H2 gas to presynthesized finely crushed THF-hydrate particles [296,299,315]. Although this method demonstrated an increasing trend in H2 storage capacity with rising H2 gas pressure (reaching 1 wt.% at 60 MPa), it is not compatible with continuous cycles as the THF or other promoter hydrate particles revert to the bulk/liquid phase upon melting.…”