Effect of Three Kinds of Graphenes on CO2 and CH4 Hydrate Formation

The slow hydrate formation rate, low storage capacity, harsh formation conditions, and environmentally contaminating promoters are the main barriers in applying carbon capture and storage (CCS) technology based on hydrate formation. In order to accelerate gas hydrate formation, three kinds of graphene nanoparticles, i.e., nonfunctionalized graphene (NFG), graphene oxide (GO), and amino graphene (AG), were applied to CO2 and CH4 hydrate formation in this work. The results show that NFG had a promoting effect on the thermodynamics of CO2 hydrate formation, while GO and AG had no effect and even exhibited an inhibiting performance. However, GO and AG effectively promoted gas consumption, with the highest CO2 consumption at 5 MPa 300 mg/L GO, and the gas consumption increased by 107.41% compared with that of the pure water–gas system. When 50 mg/L GO was added, the gas consumption was increased by 110.96% compared with pure water at 4.5 MPa. CH4 consumption was the highest, and AG at 300 mg/L was 128.77% higher than that of pure water. Overall, NFG is able to shorten the induction time while GO and AG are potential additives to improve gas consumption. The presence of oxidized groups and amine groups is the key factor inhibiting the gas hydrate nucleation.