Comparison of SDS and L-Methionine in promoting CO2 hydrate kinetics: Implication for hydrate-based CO2 storage

The continuously increasing CO 2 emissions since industrialization has sparked widespread concerns on environmental and climate change issues. Carbon sequestration and storage technologies (e.g., hydrate-based CO 2 sequestration) present promising potential for the disposing of excessive CO 2 in geological media. High gas uptake capacity and rapid CO 2 hydrate formation kinetics are required for the application of such a technology. In this study, we compared the kinetic promotion effects of sodium dodecyl sulfate (SDS) and L -methionine ( L -Met) on CO 2 hydrate with the objective of identification of an effective and eco-friendly CO 2 hydrate kinetic promoter. The experimental results suggested that L -Met (0.1 wt%) promotes CO 2 hydrates formation significantly with a gas uptake in CO 2 hydrate five times more than SDS at the same concentration. The hydrate morphology observations indicated that the wall-climbing hydrates associated with the addition of L -Met induced by the capillary driving force offer a possible explanation for the difference in the observed kinetics. A novel calculation method was developed to quantify the partition of CO 2 in gas, liquid and hydrate phases. Increasing the initial gas–liquid ratio promotes CO 2 stored in the hydrate phase as solid rather than in the liquid phase as dissolution. We further demonstrated the reusability of L -Met in five consecutive cycles of CO 2 hydrate formation and dissociation. It was assessed that L -Met as a CO 2 hydrate kinetic promoter is superior to SDS and can be employed as an efficient, reliable and eco-friendly kinetic promoter for the hydrate-based CO 2 sequestration technology.