Unveiling the Promotion Mechanism of 1,3-Dioxolane on CO ₂ Hydrate Formation in Hydrate-Based CO ₂ Sequestration: A Molecular Simulation Investigation

With the intensification of human industrial activities, atmospheric CO2 concentrations have sharply increased, aggravating the urgent global challenge of climate warming. Hydrate-based CO2 separation has emerged as a promising carbon-neutral technology; however, its practical application is hindered by low capture efficiency and slow formation kinetics. In this study, we propose and systematically evaluate the use of low-concentration 1,3-dioxolane (DIOX) as a dual-function thermodynamic and kinetic promoter for CO2 hydrate formation. Combining molecular dynamics simulations with experimental validation, we uncover the underlying mechanisms by which DIOX enhances hydrate nucleation and cage stabilization. The results show that the initial solubility of CO2 can significantly influence the formation rate of CO2 hydrates. The primary promoting mechanism of DIOX lies in the acceleration of CO2 dissolution in water, thereby facilitating the nucleation of hydrates and stabilizing the cage structure. Notably, we find that DIOX can partially occupy the 51264 cages to induce sII hydrate structures, yet at low concentrations, sI hydrates remain dominant with DIOX acting primarily as a kinetic enhancer. Furthermore, DIOX effectively suppresses CO2 precipitation and delays hydrate dissociation, offering improved storage stability. These findings provide important theoretical insights for optimizing low-concentration promoters and developing efficient CO2 hydrate-based separation technologies.