Gas Clathrate Hydrates

Nada, H. (2006). Growth mechanism of a gas clathrate hydrate from a dilute aqueous gas solution A molecular dynamics simulation of a three-phase system. J. Phys. Chem. B, 110 (33,1, 16526-16534. 

Stem, L.A. Kirby, S.H. Circone, S. Durham, W.B. (2004). Scanning Electron Microscopy investigations of laboratory-grown gas clathrate hydrates. American Mineralogist, 89, 1162-1175. 

A (gas) clathrate hydrate is a crystalline compound which can be obtained by the formation of a hydrogen-bonded host lattice around one or more species of guest molecules. It s a pleasing thought to a crystallographer that when it snows on the outer planets it might snow gas hydrates. (Jeffrey and McMullan, 1967.)... 

Figure 2.5 Three cavities in gas clathrate hydrates (a) pentagonal dodecahedron (512), (b) tetrakaidecahedron (51262), (c) hexakaidecahedron (51264), (d) irregular dodecahedron (435663), and (e) icosahedron (51268).

Natural gas clathrate hydrates normally form either in the primitive cubic structure I, in the face-centered cubic structure II, or in the hexagonal structure H. 

Hydrate research has expanded substantially over the past decade, resulting in more than 4,000 hydrate-related publications. Collating this vast amount of information into one source, Clathrate Hydrates of Natural Gases, Third Edition presents a thoroughly updated, authoritative, and comprehensive description of all major aspects of natural gas clathrate hydrates. 

Provides a historical perspective of natural gas clathrate hydrates existing from 1790 to 2006... 

The original X-ray studies of the gas clathrate hydrate structures were based on powder diffraction data, since the gas hydrates are notoriously difficult to obtain as single crystals. Clathrate hydrates formed by compounds which are liquids above 0°C, such as those of ethylene oxide and tetrahydrofuran, can be readily grown as large single crystals, and X-ray single crystal studies of both these hydrates have been carried out [787, 788]. 

Answers to such difficult questions can be found in applied thermodynamics - in terms of measured, macroscopic values of pressures, temperatures, compositions, volumes, enthalpies, etc. This chapter provides an overview of natural gas clathrate hydrates - structures, phase diagrams, and thermodynamic predictions/measurements that guide our understanding in dealing with such questions. The hydrate historical perspective provides an example of how knowledge advances in a technical field. At the conclusion of the chapter, future thermodynamic challenges are presented. 

Gas clathrate hydrates (also known as gas hydrates) are crystalline inclusion compounds composed of hydrogen-bonded water cavities (host) which encage small gas (guest) molecules. Generally, a maximum of one guest molecule occupies each water cavity. Typical guest molecules that form gas hydrates are meth-... 

Table II Phase Equilibria Data of Gas Clathrate Hydrates...

This table gives measured phase equilibria data of si and sll gas clathrate hydrates (see Table I for gas hydrate structure and physical property data). The temperature and pressure conditions at which gas... 

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