Experimental measurements and modeling of the dissociation conditions of semiclathrate hydrates of tetrabutyl ammonium nitrate and carbon dioxide

In this study, the mixed semiclathrate hydrate phase equilibrium condition of carbon dioxide in presence of various concentrations of TBANO₃ solution was determined using isochoric method. The mole fractions of TBANO₃ employed were 0.5, 1.0 and 3.0%. The presence of TBANO₃ reduces the hydrate phase equilibrium of CO₂ considerably. Increase in concentration of TBANO₃ decreases the mixed semiclathrate hydrate formation conditions. From the equilibrium data, enthalpy of dissociation of the mixed semiclathrate hydrate was calculated using the Clausius-Clapeyron equation. The calculated enthalpy of dissociation for mixed semiclathrate hydrate with various concentration employed in this study were similar suggesting formation of same type of semiclathrate hydrate structure (type b). The thermodynamic model of Paricaud [J. Phys. Chem. B 2011, 115, 288-299] was extended to fit the new experimental data.