Features of Hydrate Formation under Supercritical Conditions

Abstract

The article discusses the physical and chemical features of clathrate hydrate formation under supercritical conditions, when the hydrate former is in a state that combines the properties of gas and liquid. It is shown that in such regimes, the mechanisms of mass transfer, solubility, and nucleation of the hydrate phase are significantly altered due to the high diffusion capacity and low viscosity of supercritical fluids, as well as the blurred phase boundary. Based on the analysis of thermobaric dependencies and phase diagrams, the introduction of the concepts of pseudocritical thermobaric parameters and pseudocritical hydrate formation conditions is proposed. These concepts reflect the characteristic behavior of multicomponent hydrate-forming systems near critical states. The contribution of each component to the phase equilibrium is determined not only by its mole fraction but also by its hydrate-forming ability, which is governed by the degree of interaction with the water framework. Polarizability directly determines the induced dipole interaction between the molecules of the hydrate former and the ice-like associates of water molecules in the hydrate structure: the higher the polarizability, the stronger the change in the degree of cooperativity of hydrogen bonds, which promotes the formation of a stable clathrate; as the size of the molecule and the number of electrons increase, its polarizability also increases. The introduction of pseudocritical parameters, weighted by molar polarizability, extends the applicability of the corresponding states principle to the domain of hydrate systems and ensures the comparability of experimental and calculated data over a wide range, including supercritical conditions. Using the adjusted pseudocritical parameters, it is possible to construct universal dependencies for various mixtures, combining data for single-component and multicomponent systems in a unified dimensionless form

Please cite this article in English as:

Shostak N.A. Features of hydrate formation under supercritical conditions. Herald of the Bauman Moscow State Technical University, Series Natural Sciences, 2026, no. 4 (127), pp. 37--57 (in Russ.). EDN: RNNZLK

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