A thermodynamic framework for modeling semiclathrate hydrate phase stability conditions in gas + tetra‐n‐butyl ammonium halide aqueous solution system

To estimate the dissociation conditions of semiclathrate hydrates in gas + tetra‐n‐butyl ammonium halide aqueous solution systems, we introduce an extended thermodynamic framework, which was originally proposed by Javanmardi and colleagues for modeling of gas hydrate dissociation conditions in aqueous solutions of electrolytes (12 [1998] 219–222, Energy and Fuels). For evaluating the hydrate dissociation conditions, we apply the van der Waals–Platteuw theory. In addition, we incorporate the Peng–Robinson equation of state and the activity coefficient model of Pitzer and Mayorga to respectively calculate gas/vapor fugacity and tetra‐n‐butyl ammonium halide activity coefficient. Using this model, we have estimated the semiclathrate hydrate dissociation conditions in the systems of CH4, N2, or CO2 + tetra‐n‐butylammonium bromide + water; CO2 + tetra‐n‐butylammonium fluoride + water; and CH4 or CO2 + tetra‐n‐butylammonium chloride + water systems. The model results are found in satisfactory agreement with the selected experimental data collected from literature. Also, the average absolute temperature deviations for the studied systems are about 0.3 K.