Gas Hydrate-Based Post-combustion Carbon Dioxide Capture and Separation from Flue Gas

Gas hydrates are crystalline, non-stoichiometric inclusion compounds formed by host water molecules, which encage the guest molecules through hydrogen bonding. There exist several applications of gas hydrates including in energy (methane/natural gas) storage, gas separation, CO2 capture, desalination, etc. Considerable research efforts are put forth globally on CO2 capture, utilization, and sequestration to battle global warming and climate change. Post-combustion carbon dioxide capture encompasses a method of removing CO2 from exhaust flue gas. The development of such a technology can retrofit the existing direct flue gas emission points. In this study, we examine the kinetics of hydrate formation using a simulated flue gas mixture (75 mol % N2/25 mol % CO2) in the presence of Tetrabutyl ammonium chloride (TBAC) and L-methionine. Experiments were conducted between the 274.2–283.2 K temperature range and 8–8.8 MPa pressure. It was found that 0.5 wt% L-methionine effectively promoted the hydrate formation, resulting in a high separation factor for CO2. For different concentrations of the TBAC and L-methionine, various kinetic parameters including the gas uptake, separation factor, and t90 were calculated. Morphology observations during the formation are also presented.