Thermodynamic modeling for clathrate hydrates of ozone

We report a theoretical study to predict the phase-equilibrium properties of ozone-containing clathrate hydrates based on the statistical thermodynamics model developed by van der Waals and Platteeuw. The Patel-Teja-Valderrama equation of state is employed for an accurate estimation of the properties of gas phase ozone. We determined the three parameters of the Kihara intermolecular potential for ozone as a = 6.815 . 10 (2) nm, sigma = 2.9909 . 10 (1) nm, and epsilon . k(B) (1) = 184.00 K. An infinite set of epsilon-sigma parameters for ozone were determined, reproducing the experimental phase equilibrium pressure- temperature data of the (O-3 + O-2 + CO2) clathrate hydrate. A unique parameter pair was chosen based on the experimental ozone storage capacity data for the (O-3 + O-2 + CCl4) hydrate that we reported previously. The prediction with the developed model showed good agreement with the experimental phase equilibrium data within +/- 2% of the average deviation of the pressure. The Kihara parameters of ozone showed slightly better suitability for the structure-I hydrate than CO2, which was used as a help guest. Our model suggests the possibility of increasing the ozone storage capacity of clathrate hydrates (similar to 7% on a mass basis) from the previously reported experimental capacity (similar to 1%). (c) 2013 Elsevier Ltd. All rights reserved.