The influence of clay minerals in marine sediments – strong interactions between clay particles, water and CO2 hydrate – on hydrate-based carbon sequestration has long been a controversial topic, hampered in part by a lack of experimental evidence. In this study, we investigated experimentally and morphologically the effect of clay minerals on the nucleation and growth kinetics of CO2 hydrate in sodium montmorillonite (Na-MMT) suspensions with mass fractions ranging from 0 wt% – 10.0 wt%. The results indicated that Na-MMT greatly reduced the induction time tind by ~77%. While, the average growth rate (NR20) of CO2 hydrate was reduced by ~70% in high Na-MMT mass fraction systems (>5.0 wt%). Furthermore, significant morphological changes were identified, which were in accordance with the growth kinetics. The flakes-corolla lobes-like hydrate rapidly rises up toward spreading growth across the gas-liquid interface to the gas phase space and then extends down into bulk suspension. The clay induces significant changes in hydrate morphology, which results in the upward water migration, hydrate-clay stratification and the growth of densely packed hydrate particles.
Keywords CO2 hydrate, montmorillonite clay, formation kinetics, gas uptake, hydrate-clay morphology