An Overview of Thermodynamics and Growth Kinetics of Gas Hydrate Systems

Clathrate hydrates (or gas hydrates) belong to the class of crystalline guest-host compounds where water molecules act as hosts forming cage-like structures to entrap small guest molecules with suitable size, such as methane, ethane, CO2, and N2. The design of oil and gas production facilities and hydrate-based applications (desalination, energy storage/transportation, etc.) require a clear understanding of the thermodynamics and kinetics of gas hydrate formation. The current work encapsulates the fundamentals of thermodynamics, nucleation, and growth kinetics of gas hydrates critical in developing processes for gas hydrate-based applications. In the thermodynamics part, the original van der Waals and Platteeuw model and its modifications are discussed, and the challenges with inhibited hydrate phase equilibria measurements and predictions are highlighted. Nucleation and growth kinetics of gas hydrates are also briefly reviewed to present the current state of understanding in this field. While gas hydrate thermodynamics is reasonably well understood, the understanding of nucleation and growth kinetics of gas hydrates is relatively poor. However, molecular simulations have advanced our understanding considerably in recent years.