[Paper Review] Molecular simulation of methane hydrate growth confined into a silica pore

Ángel M. Fernández-Fernández, M. M. Conde+3 more|arXiv (Cornell University)|Jan 4, 2026

Methane Hydrates and Related Phenomena0 citations

TL;DR

This study uses all-atom MD to simulate methane hydrate growth inside a silica slit pore, showing defected hydrate structure and a high-density water layer trapped between the walls and crystallized hydrate.

ABSTRACT

The growth of a methane hydrate seed within a silica slit pore of fixed width has been studied using AllAtom Molecular Dynamics (AA-MD). An AA force field has been used to describe the molecules of the solid silica substrate, with a-quartz crystalline structure. The crystallisation of hydrates in confined geometries is not well understood yet, and the objective of this work is to study the hydrate growth inside a silica pore using molecular simulation. Both NVT and NpT ensembles were used in the AA-MD simulations to analyse the hydrate growth from an initial seed. Results showed that the boundary conditions imposed by the nanometric slit pore yielded a hydrate with structural defects, filling the accessible space between the silica walls. The water molecules which were not incorporated to the initial seed hydrate formed a high density water layer trapped between the silica walls and the crystallised hydrate. These results provide an interesting insight into the hydrate crystallisation process in confined geometries, resembling those found in natural hydrate deposits.

Motivation & Objective

• Investigate how confinement in a nanometric silica slit pore affects methane hydrate growth.
• Understand structural defects and space filling behavior of hydrates formed from an initial seed.
• Explore the role of confinement on water distribution during hydrate crystallization."
• Assess how boundary conditions in confined geometries resemble natural hydrate deposits.

Proposed method

• All-atom Molecular Dynamics (AA-MD) simulations.
• Silica substrate modeled with a-quartz crystalline structure and an AA force field.
• Hydrate growth studied from an initial seed under NVT and NpT ensembles.
• Analysis of hydration structure and space filling within the pore."

Experimental results

Research questions

• RQ1 How does confinement within a silica slit pore influence methane hydrate growth compared to bulk systems?
• RQ2 What structural defects arise in hydrates grown in confined geometries?
• RQ3 What is the behavior of free water that is not incorporated into the seed during confinement?
• RQ4 How do boundary conditions in nanometric pores affect the crystallisation process of methane hydrates?

Key findings

• The confined pore boundary conditions yield a hydrate with structural defects that fills the accessible space between silica walls.
• Water molecules not in the seed form a high-density water layer trapped between the silica walls and the crystallised hydrate.
• Hydrate growth in confinement provides insights into crystallisation processes relevant to natural hydrate deposits."
• Use of both NVT and NpT ensembles elucidates the dynamics of hydrate growth under fixed and pressure-controlled conditions.