Methane Hydrate in Activated Carbon
Recently it has been discovered that methane can form a hydrate structure with water in activated carbons. The storage density of methane on wet activated carbon has been shown to be greater than when it is compressed or adsorbed on dry activated carbon for pressures greater than the hydrate formation pressure (5MPa at 3oC). Similar to bulk phase hydrate, the formation of hydrate in activated carbon is favoured by low temperatures and high pressure. Below the hydrate formation pressure, the adsorption of methane is significantly less than that on dry activated carbon due to the pores being filled with water. Experiments have been conducted over a range of temperatures from 0oC to 20oC and pressures up to 20MPa. By using Monte Carlo simulations it is possible to analyse in which pores the hydrate is formed and in which pores methane still adsorbs by the normal mechanism of layering. The properties of the activated carbon which most strongly affect the storage capacity are discussed together with its potential for methane storage.