Holzammer Christine C, Braeuer Andreas S
Institute of Thermal-, Environmental-, and Resources' Process Engineering (ITUN) , Technische Universität Bergakademie Freiberg (TUBAF) , 09599 Freiberg , Germany.
Erlangen Graduate School in Advanced Optical Technologies (SAOT) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Paul-Gordan-Str. 6 , 91052 Erlangen , Germany.
J Phys Chem B. 2019 Mar 14;123(10):2354-2361. doi: 10.1021/acs.jpcb.8b11040. Epub 2019 Mar 1.
We present an experimental Raman study on the thermodynamic inhibition effect of different salts (NaCl, KCl, MgCl, and CaCl from 2.5 to 11 wt %) on the formation of carbon dioxide gas hydrates. We performed the experiments in a high-pressure vessel with two phases: a water-rich phase and a CO-rich phase. We investigated the changes the inhibitors induce in the water-rich phase before the onset of hydrate formation. This includes a study of the change in molar reaction enthalpy between strongly and weakly hydrogen-bonded water and the decrease in solubility of carbon dioxide in water. Additionally, the growth mechanisms of carbon dioxide hydrates were investigated by determining the amount of solid hydrates formed and the reaction constant. The results show that the molar reaction enthalpy, the solubility of CO, and the amount of solid hydrates formed can be correlated with the effective mole fraction, whereas the reaction constant is not affected by the addition of salts. The decrease of the molar reaction enthalpy can be directly correlated with the equilibrium temperature of the gas hydrates.
