Equilibrium Data and Thermodynamic Modeling of Nitrogen, Oxygen, and Air Clathrate Hydrates

Air hydrates can form at high-pressure and low-temperature conditions found in deep ice sheets of Arctic and Antarctic regions. These hydrates can play a major role in analyzing the data gathered in these regions. However, there are limited experimental data and thermodynamic modeling on air hydrates. In this work, we present new experimental data on methane, nitrogen, oxygen, and air hydrates. An experimental setup based on a quartz crystal microbalance (QCM) has been used in measuring all the experimental data reported in this work. The QCM method needs much smaller samples, resulting in a significant reduction in the time required for each experiment. The available data on oxygen hydrates are used in optimizing the Kihara potential parameters for oxygen hydrates. Using the previously reported nitrogen Kihara potential parameters and the optimized Kihara potential parameters for oxygen, the hydrate stability zone of air hydrates (21 mol % oxygen and 79 mol % nitrogen) has been predicted. The predictions of the thermodynamic model are in good agreement with the independent experimental data on air hydrates, demonstrating the reliability of experimental and modeling techniques used in this work.