Guest Molecular Networks Directing Hydrate-Based Methane Storage.

Abstract

Natural gas hydrates are promising unconventional clean energy resources, and clarifying methane hydrate nucleation is critical for their efficient exploitation, gas storage, and carbon sequestration. Here, we challenge the conventional water-dominated hydrate nucleation view by revealing a guest-dominated mechanism where guest molecule networks (GMNs) formed by solvent-separated methane pairs act as active inductive frameworks. Microsecond-scale molecular dynamics simulations show that GMNs undergo crystalline ordering nearly 200 ns earlier than the water hydrogen-bond network (HBN), and triangular GMN motifs template water reorganization into cage-like configurations to form amorphous critical nuclei. We describe GMN evolution using complementary local-geometrical and bond-orientational descriptors and examine their temporal association with subsequent HBN ordering and cage formation. Machine learning models trained on GMN order parameters accurately predict hydrate cage formation on submicrosecond timescales. These findings establish GMNs as structural precursors associated with hydrate nucleation, providing a predictive framework for controlling nucleation processes. This work offers fundamental molecular insights for optimizing NGH exploitation, methane storage, CO2 sequestration, and gas separation technologies, and a generalizable approach for understanding crystallization in energy-related multi-component systems.