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In this work, the thermodynamics and kinetics of hydrate formation in 9.01 wt% tetra butyl ammonium bromide (TBAB) mixed with water-soluble hydroxylated multi-wall carbon nanotube (MWCNTol) systems were characterized by measuring hydrate formation conditions, induction time, and final gas consumption. The results showed that MWCNTols had little effect on the phase equilibrium of CO2 hydrate formation. Nanoparticles (graphene nanoribbons (GNs) and MWCNTols) could significantly shorten the induction time. When the concentration was ≤0.06 wt%, MWCNTols had a better effect on the induction time than the GN system, and the maximum reduction in induction time reached 44.22%. The large surface area of MWCNTols could provide sites for heterogeneous nucleation, thus shortening the induction time of hydrate formation. Furthermore, adding different concentrations of nanoparticles to the 9.01 wt% TBAB solution effectively increased the final gas consumption, and the maximum increase was 10.44% of the 9.01 wt% TBAB + 0.08 wt% GN system. Meanwhile, the suitable initial pressure and experimental temperature could also promote the hydrate formation and increase the motivation in hydrate formation. The 9.01 wt% TBAB + 0.02 wt% MWCNTol system had the best effect at 3.5 MPa and 277.15 K. The induction time was reduced by 66.67% and the final gas consumption was increased by 284.11% compared to those of the same system but at a different initial pressure and experimental temperature. This work helps to promote the industrial application of hydrate technology in CO2 capture and storage. [ABSTRACT FROM AUTHOR]

Hydrate based CO 2 separation process is affected by many factors which mainly includes additive concentration, gas-liquid volume ratio and operating conditions. The most of the investigations on the CO 2 hydrate-based separation in the previous work were carried out around the kinetics and thermodynamics of the hydrate formation along with the CO 2 separation efficiency. However, few studies focus on the morphology of hydrate though the difference of the morphologies directly leads to the difference of the CO 2 separation efficiency. In this work, the morphology along with the kinetics of the hydrate-based CO 2 separation from CO 2 /H 2 (40%/60%) is carried out in the presence of tetra- n -butyl ammonium bromide (TBAB) of 0.29 mol%. The results indicate, firstly, TBAB hydrate formation and TBAB/gas mixture hydrate formation were two independent processes. Secondly, the different operating conditions resulted in different hydrate morphologies. Thirdly, the consumption of CO 2 in low pressure (<2.5 MPa) was controlled by the driving force, while that was controlled by the formed hydrate layer in the gas-liquid interface in the relatively high pressure especially for the initial pressure ≥4.5 MPa. [ABSTRACT FROM AUTHOR]