Formation and Properties of Gas Hydrates

Knowledge concerning the mechanism of hydrates formation is important in designing inhibitor systems for hydrates. The process of formation is believed to occur in two steps. The first step is a nucleation step and the second step is a growth reaction of the nucleus. Experimental results of nucleation are difficult to reproduce. Therefore, it is assumed that stochastic models would be useful in the mechanism of formation. Hydrate nucleation is an intrinsically stochastic process that involves the formation and growth of gas-water clusters to critical-sized, stable hydrate nuclei. The hydrate growth process involves the growth of stable hydrate nuclei as solid hydrates [129]. 

Surfactants like sodium dodecyl sulfate reduce the surface tension at the liquid-gas interface considerably. In fact, the addition of surfactants in small 

Nucleation and growth of gas hydrate crystals have been investigated with optical methods under different pressures and temperatures. The particle sizes measured during gas hydrate nucleation ranged from 2 to 80 imi [1334,1335]. The nucleation process is nondeterministic, because of a probabilistic element within the nucleation mechanism [1393]. 

A controversy exists regarding the early stages of formation of gas hydrates. The mechanism proposed by Sloan and Fleyfel [384,613,1637] for the kinetics of hydrate formation is composed of 

The formation of clusters of hydrogen-bonded water molecules around different sizes of apolar molecules 

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