Experimental study of carbon dioxide gas hydrate formation in the presence of zwitterionic compounds

In this work, the effect of a series of zwitterionic compounds (ZIs) aqueous solutions on the thermodynamic equilibrium and kinetic conditions of carbon dioxide hydrate formation is investigated. The hydrate dissociation conditions for (CO2 + ZI + water) systems are studied at different concentrations of ZI, viz. (0.10; 0.20, 0.30) mass fraction. The experiment was performed over a temperature range of T = (272-282) K and pressures range of p = (1.27-4.31 MPa) using a high pressure equilibrium cell. In this work the following ZIs: 4-(triethylammonio)butane-l-sulfonate [N222C4S], 4-(tributylammonio)-butane-1-sulfonate [N444C4S] and 4-(tributylphosphonio) butane-1-sulfonate [P444C4S] were investigated, therefore it was possible to determine the influence of alkyl chain length and the structure of the core atom on the kinetic behaviour of carbon dioxide gas hydrate formation. The results show that the gas hydrate phase equilibrium in the presence of zwitterionic compounds is shifted to higher pressures and lower temperatures so that the ZIs act slightly as a thermodynamic inhibitor of hydrate formation. (C) 2019 Elsevier Ltd.