Influence of Guest Molecular Mass on Gas Hydrate Nucleation via Molecular Simulation

Abstract

Hydrates are ice-like crystals. Its nucleation event has important significance for many industrial fields, such as seawater desalination, gas separation, and gas storage. Therefore, researchers are looking for a kind of highly effective promoters to accelerate hydrate nucleation and stabilize hydrate crystals so that hydrate-based technology can be sustainable and economical. Herein, we use the molecular simulation method and construct ideal guest molecules to study the influence of guest molecular mass on the hydrate nucleation process. Our results show that lighter guest molecules nucleate more easily. However, when the light and heavy guest molecules coexist, the light guest molecules can only enhance the formation of the nucleation precursor but cannot effectively reduce the free energy barrier of hydrate nucleation because of the competition between the light and heavy guest molecules around the critical nuclear state. Overall, our work provides a theoretical basis for the development of hydrate promoters, which is expected to be helpful for their efficient design.