Deciphering the Roles of Dispersed Solid Particulate Additives in THF Hydrate Induction and Crystal Growth

The unique structural characteristics of hydrates endow them with broad application prospects across various fields. However, the inherent stochasticity of nucleation induction time remains a primary obstacle to the commercialization of hydrate-based technologies. Encouragingly, some solid particles have been identified as effective kinetic promoters that can substantially shorten this induction period. To clarify the effect of particle properties on hydrate formation kinetics, this study systematically investigates the influences of nano-SiO₂ (n = 9), SBA-15 (n = 14), and lignite (n = 21) on THF hydrate nucleation using a temperature-controlled optical microscopy system at -13 °C. The experimental results reveal that all three additives can reduce the THF hydrate nucleation induction time across repeated measurements, and the reduction trends vary with additive dosage. Within the tested mass concentration range, nano-SiO₂, SBA-15, and lignite achieve maximum induction time reduction rates of 60.39%, 86.51%, and 94.33%, respectively. Among them, nano-SiO₂ exhibits a nonmonotonic trend with an optimal nucleation mass concentration of 0.5 mg·mL^-1. The promoting effect of SBA-15 gradually weakens as concentration rises, with its optimal induction time observed at 0.2 mg·mL^-1. For lignite, hydrate nucleation is monotonically accelerated with increasing dosage. The hydrate promotion performance of these substances is governed by multiple factors. The proposed mechanisms, involving physical structure, pore confinement, and chemical composition, may provide references for interpreting the experimental observations.