This paper reports an experimental study to further increase the ozone storage capacity in a clathrate hydrate and to better understand the relationship between the gas phase O3 concentration and the O 3 storage capacity in the hydrate. We performed experiments with the O3 + O2 + CO2 feed gas with an increased O 3 fraction in the gas phase exceeding that covered by a preceding study. To accurately specify the thermodynamic conditions to form the hydrate, we first measured the three-phase (gas + liquid + hydrate) equilibrium conditions for the (O3 + O2 + CO2 + H 2O) and (O2 + CO2 + H2O) systems. The phase equilibrium data cover the temperature range from 272 to 277 K, corresponding to pressures from 1.6 to 3.1 MPa, for each of the two different (O3 + O2)-to-CO2 or O2-to-CO 2 molar ratios in the feed gas, which are approximately 4:6 and 5:5, respectively. The O3 fraction in the gas phase was ∼0.025. Based on the equilibrium data, we prepared crystal samples of the O3 + O2 + CO2 hydrates at a system pressure of 3.0 MPa and a temperature of 272 K. The highest O3 storage capacity in the hydrates was measured to be 2.15 mass% which is 2.36 times higher than the highest past record of 0.91 mass%. The results also show that the dominant factor to control the O3 storage capacity in the hydrates is the O3 mole fraction in the gas phase in contact with the hydrates.
ASJC Scopus subject areas
- Materials Chemistry