Aluminum-Based Promotion of Nucleation of Carbon Dioxide Hydrates

Gas hydrate formation has several applications in CO₂ sequestration, flow assurance, and desalination. Nucleation of hydrates is constrained by very high induction (wait) times, which necessitates the use of complex nucleation promotion techniques to form hydrates. Presently, we report the discovery of a simple, passive nucleation promotion technique, wherein an aluminum surface significantly accelerates nucleation of CO₂hydrates. Statistically meaningful measurements of induction times for CO₂ hydrate nucleation were undertaken using water droplets as individual microsystems for hydrate formation. The influence of various metal surfaces, droplet size, CO₂ dissolution time, and the presence of salts in water on nucleation kinetics was characterized. Interestingly, we observe nucleation initiation only on aluminum surfaces, the influence of which cannot be replicated by salts of aluminum. We discover that the aluminum–water interface is responsible for nucleation promotion. We hypothesize that hydrogen bubbles generated at the aluminum–water interface are responsible for nucleation promotion.