Thermodynamics and Applications of CO2 Hydrates

Hydrate is a term related to a substance that contains water of crystallization. In inorganic chemistry, hydrates refer to inorganic salts that have water molecules crystallized with salt compounds in a definite ratio. An example is copper sulfate, which turns from gray-white (anhydrous form) to blue (pentahydrate) uptm hydration. Such hydration can easily be carried out by dissolving anhydrous (water free) copper sulfate in water and crystallizing. Laboratory research reveals that five water molecules occur in a copper sulfate crystal unit, and four of them are attached to the copper ion by coordination bonds, whereas the fifth is supposed to be held to sulfate 

Co-authored by Junjie Zheng, Ponnivalavan Babu, and Praveen Linga, Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore with the Singapore Ministry of Education, MOE s Tier 1 (R-279-000-386-112) financial support. 

Aresta et al., Reaction Mechanisms in Carbon Dioxide Conversion, DOI 10.1007/978-3-662-46831-9 10 

Another class of hydrates is gas hydrates. Unlike the stoichiometric inorganic salt hydrates, gas hydrates are nonstoichiometric clathrate soUd crystalline substances consisting of a lattice formed by water molecules (host) and entrapped gas molecules (guest). They are stable under high pressure and low temperature. The hydrate formation reaction can be described by the following general equation  

The right combination of pressure and temperature (high pressure and low 

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