Thermodynamic Stabilities of Tetra-n-butyl Ammonium Chloride + H₂, N₂, CH₄, CO₂, or C₂H₆ Semiclathrate Hydrate Systems

Abstract

The thermodynamic stabilities of semiclathrate hydrates were investigated in the tetra-n-butyl ammonium chloride (TBAC) aqueous solution (mole fraction of TBAC is 0.0323) + H2, + N2, + CH4, + CO2, and + C2H6 systems. The dissociation temperature of each semiclathrate hydrate is higher than that of the simple TBAC semiclathrate hydrate (hydration number is 30) except for the C2H6-containing system in the whole pressure region under the present experimental conditions. Isobaric dissociation temperatures of the TBAC + H2, + N2, + CH4, and + CO2 hydrates increase in this order. The temperature−pressure projection indicated that the hydrate structural transition occurs around 3 MPa in the TBAC + CH4 semiclathrate hydrate system, while the three-phase equilibrium curves of the other TBAC hydrate systems do not show any discontinuity in gradient under the present conditions.

Dissociation behaviour of (tetra-n-butylammonium bromide + tetra-n-butylammonium chloride) mixed semiclathrate hydrate systems

“…For example, the following dissociation temperatures have been reported in ascending order of size: T = 301 K for TBAF and TBA hydroxide hydrates [7,14,15], T = 288 K for TBA chloride (TBAC) hydrate [3,11], and T = $286 K for TBAB hydrate [9][10][11]. Such semiclathrate hydrates can be stable at temperatures between T = (273 and 300) K, and are capable of trapping small gas molecules (e.g., H 2 , CH 4 , CO 2 , and N 2 ) under milder conditions than those required for the corresponding pure gas hydrate (e.g., [16] storage materials have been carried out by many research groups (e.g., [16][17][18][19][20][21][22][23][24][25]). In particular, fundamental and applied studies on TBAB hydrates have been conducted in detail because of the relatively noncorrosive nature of this hydrate system.…”

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

“…×, CO 2 + 0.0874 mass fraction TBAC aqueous solution . Δ, CO 2 + 0.3398 mass fraction TBAC aqueous solution…”

Investigation of kinetics of tetrabutylammonium chloride (TBAC) + CH4 semiclathrate hydrate formation

“…3 showed the experimental conditions as well as equilibrium data of double (TBAC + CH 4 ) SCHs. [43][44][45] It could be seen that the experimental temperatures were higher than the equilibrium temperatures of pure CH 4 hydrate at the same pressure. Hence it could provide a more economical method for hydrated based gas storage.…”