Thermodynamic and Kinetic Promoters for Gas Hydrate Technological Applications

In recent years, there has been growing interest in gas hydrates as technological applications, such as for energy (methane and hydrogen) storage and transportation, separation (gas and desalination), and carbon capture. However, there are several challenges that deter large-scale applications and commercialization of these hydrate-based technologies. One of the main challenges is the long induction time and slow growth of hydrate particles, which can increase the overall operating costs of these technologies. It has been reported that the addition of additives (known as hydrate promoters) can help improve the nucleation and growth rate of hydrates. In general, there are two types of hydrate promoters: thermodynamic hydrate promoters and kinetic hydrate promoters. Thermodynamic hydrate promoters shift the hydrate equilibrium curve to milder conditions (i.e., lower pressures and higher temperatures), while kinetic hydrate promoters reduce the induction time for hydrate formation and increase the growth rate. In this review, we provide a comprehensive review of the two types of hydrate promoters (thermodynamic and kinetic) and their effects on hydrate phase equilibria, induction time, and growth rate.