A molecular mechanism for gas hydrate nucleation from ice

Modelling of hydrate formation kinetics: State-of-the-art and future directions

“…An explanation for the results of Barrer and Edge (1967) and Falabella (1975) was proposed by Sloan and Fleyfel (1991). Taking into account that both methane and krypton present very close values for the ratio of the guest molecule diameter to the 5 12 cavity diameter in both sI and sII structures, Sloan and Fleyfel (1991) stated that the induction period would be the result of an oscillation between these two kinds of crystalline structure, until the more stable one reached r c and effectively started to grow.…”

“…Taking into account that both methane and krypton present very close values for the ratio of the guest molecule diameter to the 5 12 cavity diameter in both sI and sII structures, Sloan and Fleyfel (1991) stated that the induction period would be the result of an oscillation between these two kinds of crystalline structure, until the more stable one reached r c and effectively started to grow. With the aim of verifying their hypothesis, these authors experimentally studied the kinetics of formation of cyclopropane hydrates, which, depending on the adopted temperature and pressure, may exhibit either sI or sII structure.…”

Studies of hydrate nucleation with high pressure differential scanning calorimetry

“…The stochastic nature of the nucleation event can often lead to large variations in the onset time for hydrate formation between experiments (Maini and Bishnoi, 1981;Englezos et al, 1987;Christiansen et al, 1994). Researchers have also focused on the molecular mechanisms for hydrate nucleation (Sloan and Fleyfel, 1991;Radhakrishnan and Trout, 2002), but a major drawback has been the difficulty in obtaining sufficient laboratory data to validate the proposed mechanisms.…”

Hydrates in the ocean and evidence for the location of hydrate formation

“…On the basis of hydrate nucleation from ice [10][11][12], Sloan and Fleyfel [13] proposed a new hypothesis to describe the molecular mechanism for gas hydrate nucleation from ice; the hypothesis was later extended to hydrate formation from water [ 14]. The model used a new physical parameter, namely, the guest/cavity size ratio.…”