Rapid formation of carbon dioxide hydrate governed by the natural nano-clay for effective carbon dioxide capture

Abstract

Gas hydrate can separate and capture enormous carbon dioxide (CO₂) only using water cages. Capturing CO₂ in hydrate form is viewed as a green and effective technology to reduce the global CO₂ emission. However, the sluggish kinetics and high cost of kinetics promotors of CO₂ hydrate formation limited the application of hydrate-based CO₂ capture technology. Here, we used the nano-clay prepared by cheap natural clay to promote the formation kinetics of CO₂ hydrate. At the low concentration range, the formation period of CO₂ hydrate in the two-dimensional nano-clay dispersion was significantly shorter than that of the one-dimensional nano-clay dispersion. The induction time (5 min) obtained in vermiculite nanoflakes dispersion was shorter than most solid promotors of CO₂ hydrate formation kinetics in reported works. Besides, we found that the water molecules near the negatively charged two-dimensional nano-clay surface were more likely to form the cage-like structure than those around the one-dimensional nano-clay surface. The similar hydrogen-bonded structure of the cage-like water with CO₂ hydrate made them favorable for the CO₂ hydrate formation. These results shed light on the design of the effective kinetics promotors of CO₂ hydrate and contribute to develop the hydrate-based CO₂ capture technologies.