High pressure DSC study of mixed semi-clathrate hydrates of tetra-n-butylammonium bromide and CO2, N2 and (CO2 + N2) and ( CO2 + CH4) mixtures
Abstract
Semi-clathrate hydrates, also known as ionic clathrates, are supra-molecular compounds in which an organic cation is enclathrated into an aqueous lattice while the anion takes place in the water framework. Semi-clathrates of peralkylonium salts have been studied extensively [1]. Since the capability of entrapping gas molecules into various semi-clathrates was demonstrated, these compounds have been proposed as materials in a variety of novel processes, including phase change materials for cold transport, hydrogen storage materials and CO2 capture media in gas mixtures.
The objective of the present study, conducted within the framework of SECOHYA* project funded by the French “Agence Nationale de la Recherche”, is to demonstrate the possibility of using semi-clathrates to separate CO2 in gas mixtures such as natural gas or combustion exhausts. We present results of determinations of pressure-temperature domains of formation, and the associated enthalpy change, of semi-clathrate hydrates of tetra-n-butylammonium bromide (TBAB) with various gases and gas mixtures containing CO2.