Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

In this study, the thermophysical properties of lysine amino acid, alongside its methane and carbon dioxide hydrate inhibition effect is reported. The physical properties (density, viscosity, and refractive index) of aqueous lysine solution are measured at 5 wt% and 10 wt% in the temperature range of (298.15 to 313.15) K at 5 K intervals. The hydrate inhibition potential of lysine is tested in the temperature and pressure range of (1.87 to 10.45) MPa and (276.45 to 285.15) K, respectively, at 5 wt% and 10 wt% using the T-cycle method in a sapphire cell hydrate reactor. The density, viscosity and refractive index of the aqueous lysine solution are found to increase with increasing concentration, but decreases with increasing temperature. Furthermore, the presence of lysine significantly inhibited both methane and carbon dioxide hydrate by shifting the methane and carbon dioxide hydrate equilibrium phase boundary condition to higher pressures and/or lower temperatures region. The lysine hydrate inhibition impact is increased with increasing concentration. An average depression temperature of 1.44 K and 1.49 K is observed at 10 wt% for methane and carbon dioxide hydrate, respectively. In addition, the hydrate dissociation enthalpies in the presence and absence of lysine are calculated using the Clausius-Clapeyron equation. The findings are useful as it presents data which can be used to understand the effect of amino acids physical properties on their thermodynamic hydrate inhibition influence.