Pase equilibria for semiclathrate hydrate formed with CH4, CO2 and CH4+CO2 gas mixture in presence of tetrabutylphosphonium bromide and tributylphosphine oxide
Abstract
Gas hydrates or clathrate hydrates are crystalline compounds formed by a combination of guest molecules and a network of water molecules. They are formed at under suitable condition of high pressure and low temperature. On the other hand, using some promoters it is possible to form the called semiclathrates at significantly lower pressure and higher temperature. Some small cages dodecahedral cavities are available in the structure of these solids and can encaged small gas molecules, such as CH4, CO2 and H2S. In recent years, research involving gas separation and gas storage process using semiclathrate formation have increased substantially. These processes require knowledge about phase diagram of the system containing the gas and the additive in aqueous solution. Several kinds of promoters have already been studied, but mostly for pure gases. Works involving the gas mixture are still rare. In this work we studied the equilibrium conditions for semiclathrate formation for two promoters: Tetrabutylphosphonium bromide (TBPB) and tributylphospine oxide (TBPO) are promising promoters