2-4-2 Nucleation and Dissociation Behavior of TBAB Semiclathrate Hydrate

Abstract

The structural variety of tetra-n-butyl ammonium bromide (TBAB) semiclathrate hydrate implies that its crystal structure is relatively soft and easily disordered. To elucidate the structural variety of the TBAB semiclathrate hydrate and to solve the large supercooling for the TBAB semiclathrate hydrate nucleation, the equilibrium pressure– temperature relations of TBAB semiclathrate hydrate were measured at pressures up to 80 MPa by the high-pressure differential scanning calorimetry (DSC). As a pressurizing medium, tetrafluoromethane (CF₄) was used. The dissociation temperature of tetragonal TBAB semiclathrate hydrate increases with the increase in pressure, while the dissociation enthalpy is 192±3 J/g and almost constant at pressures up to 80 MPa. The maximum allowable degree of supercooling is 17.7±0.7 K and independent of the pressure.