Clathrate Hydrates

Abstract

Hydrogen fuel, if provided via a green method, is renewable and environmentally friendly. However, the lack of practical storage methods has restricted its use to such an extent that hydrogen storage is currently a crucial obstacle in the development of a hydrogen economy. The challenge, particularly for mobile applications, is that the hydrogen storing system needs to be lightweight and compact. The two most popular methods currently being used are the storage of hydrogen as compressed gas under high pressures, or as a cryogenic liquid. To approach the goals required to develop a hydrogen economy, researchers are investigating a range of different techniques.A practical hydrogen storage method must satisfy a number of requirements [1]:1) high hydrogen content per unit mass 2) high hydrogen content per unit volume 3) moderate synthesis pressure (preferably less than 400 MPa, the pressure that can be reached by a simple compressor) 4) near ambient pressure and moderate temperature for storage 5) fast and efficient hydrogen release 6) environmentally friendly byproducts, if any.The most common ways of storing hydrogen fuel as liquid hydrogen and compressed hydrogen gas have the drawbacks that the fuel needs to be stored at extremely low temperatures (20 K for liquid hydrogen) or at high pressures (35 MPa for compressed hydrogen) [2]. To overcome such issues, much attention is currently being given to storing hydrogen in solid-state materials. Recently emerging materials include doped carbon-based nanostructures [3], metal organic frameworks [4], metallic hydrides [5], complex hydrides and destabilized hydrides [6, 7]. However, no material so Handbook of Hydrogen Storage. Edited by Michael Hirscher

Hydrogen Storage Capacity of Tetrahydrofuran and Tetra-N-Butylammonium Bromide Hydrates Under Favorable Thermodynamic Conditions

“…While the majority of hydrate research funding and activities currently are directed toward investigations of natural gas hydrates, there is interest in hydrate storage of H 2 for transportation applications [1,2]. Pure H 2 hydrate requires very high pressures, which makes them impractical under most storage scenarios [1][2][3].…”

“…Pure H 2 hydrate requires very high pressures, which makes them impractical under most storage scenarios [1][2][3]. In order to reduce the prohibitively high pressure requirement, H 2 mixed gas hydrates have been investigated [1][2][3][4][5].…”

“…Pure H 2 hydrate requires very high pressures, which makes them impractical under most storage scenarios [1][2][3]. In order to reduce the prohibitively high pressure requirement, H 2 mixed gas hydrates have been investigated [1][2][3][4][5]. Hashimoto et al [6] demonstrated that adding small amounts of tetra-n-butylammonium bromide (TBAB; C 16 H 36 NBr) to water reduced the hydrogen hydrate formation pressure from 350 MPa to~1 MPa at 280 K. TBAB is a salt that forms a semi-clathrate hydrate crystal (C 16 H 36 N + ·Br − ·38H 2 O) at atmospheric pressure and near room temperature with a unit-cell composed of 16 small (S)-cages and eight large (L)-cages.…”