Methane hydrate nucleation frustration and dimensional reduction of structural order under nanoconfinement

TL;DR

This study explores how nanoconfinement affects methane hydrate formation, revealing suppressed nucleation and reduced molecular order dimensionality in water-methane systems confined between silica slit pores.

Contribution

It provides new insights into the structural organization and nucleation frustration of methane hydrates under nanoconfinement conditions.

Findings

Hydrate-like ordering is suppressed below 2 nm confinement.

Two-dimensional correlations show pronounced in-plane organization.

Confinement reduces the dimensionality of molecular order.

Abstract

Methane hydrate nucleation under nanoconfinement remains poorly understood due to the complex interplay between geometric restriction and molecular ordering. Here, we investigate the structural organization of water-methane systems confined between silica planar slit pores with widths ranging from 1 to 5 nm and temperatures between 250 and 295 K. Three-dimensional radial distribution functions reveal a clear suppression of hydrate-like ordering at strong confinement (below 2 nm), indicating frustrated nucleation. In contrast, projected two-dimensional correlations exhibit pronounced in-plane structural organization, evidencing a confinement-induced reduction in the dimensionality of molecular order.