Facilitating clathrate hydrates with extremely rapid and high gas uptake for chemical-free carbon capture and methane storage

Clathrate hydrates are crystalline solid compounds comprising water and gas with remarkable potential for energy storage and carbon capture because of their large gas storage capacity and ability to selectively capture certain species upon crystallization. However, their use in real life has been hindered by low gas uptake kinetics, primarily limited by mass transfer. While extensive efforts have been made to overcome this limitation using chemical additives, their kinetic effects are insufficient, and environmental problems are caused. Here, the highest CO2 and CH4 gas uptake kinetics ever reported in clathrate hydrates were achieved without any chemical additives or mechanical mixing. The CO2 gas uptake rate and amount far exceeded previous records by 55.3% and 21.6%, respectively. Such excellent kinetics were accomplished using a fixed-bed reactor filled with surface-modified silica sand, which can be easily produced by simple treatment. Raman analysis and morphological studies demonstrated that its hydrophobic surface significantly affects interfacial interactions with water, greatly enhancing mass transfer. This new method is energy-efficient and environment-friendly, not requiring mechanical mixing or chemical injection at all. Mechanistic understandings of hydrate formation with hydrophobic surfaces would be applicable to hydrate-based carbon capture, methane storage, and natural gas hydrate production systems.