Molecular dynamics insights into tetrahydrofuran-assisted formation of CH4, CO2, and H2 gas hydrates

Abstract

Gas hydrates, also known as clathrate hydrates, are crystalline compounds formed when water molecules organize into cage-like structures that encapsulate gas molecules under conditions of high pressure and low temperature. These hydrates occur naturally in permafrost regions and deep-sea sediments and have gained significant interest as potential energy sources and for applications in gas storage, transportation, and sequestration. Here, we deploy molecular dynamics (MD) simulations to investigate the molecular-level mechanisms governing the formation and stabilization of CH4, CO2, and H2 hydrates in the presence of tetrahydrofuran (THF). We analyze key structural and energetic properties, including tetrahedral order parameters, cage dynamics, and gas uptake throughout different hydrate formation stages: pre-nucleation, nucleation (induction), growth, and saturation. Our findings provide insights into the role of THF concentration in altering hydrate phase behavior, as well as kinetic and gas occupancy preferences within hydrate cages. The study offers a comprehensive understanding of hydrate nucleation mechanisms and thermodynamic stability, contributing to advancements in gas hydrate applications for energy and environmental technologies.