Enhanced CO₂ Hydrate Formation Using l‑methionine and SiO₂ Nanoparticles as Combined Kinetic Promoters

In this study, l-methionine (l-Met) and l-Met + SiO₂ nanoparticle systems were investigated for CO₂ hydrate formation through kinetic measurements and direct morphological observation. l-Met significantly promoted hydrate formation, with 0.100 wt % identified as the optimum single-promoter concentration.

The enhancement was closely associated with the formation of a porous wall-climbing hydrate layer, which improved gas–liquid contact and sustained hydrate growth through capillary-assisted water supply. Introducing SiO₂ nanoparticles into the optimized l-Met system further enhanced the formation kinetics within an appropriate concentration range, with the 0.100 wt % l-Met + 0.10 wt % SiO₂ formulation selected for the subsequent five-cycle evaluation based on the combined mean performance of induction time, final normalized gas consumption, and <i>t</i>₉₀.