Kinetic Measurements on CO₂ Hydrate Formation in the Presence of Tetra-n-butyl Ammonium Bromide

Abstract

Ionic clathrate hydrates are promising materials for hydrate-based CO2 capture due to their mild forming conditions. In this work, hydrate crystallizations from different TBAB solutions were measured. The effect of TBAB concentration on hydrate nucleation time, hydrate growth, and gas storage capacity were evaluated. The TBAB concentration ranging from 0.3 to 7.5 mass % was found to be ideal for efficient hydrate formation. The TBAB hydrates were assumed to form first in the liquid bulk which induced the growth of simple CO2 hydrate. In dilute TBAB solutions, guest ions in TBAB tended to inhibit hydrate nucleation and increase induction time, while concentrated TBAB solutions were found to reduce gas storage capacities. PXRD measurements revealed that the orthorhombic TBAB hydrate preferred to form where TBAB concentration was below 35 mass %. When the concentration was above 40 mass %, tetragonal and trigonal TBAB hydrate dominated the solid hydrate phase. In Raman measurements, C–H stretching modes of the TBA+ cation in different hydrate structures were characterized. CO2 was proved to be captured by tetragonal and orthorhombic TBAB hydrates, which was suggested to be beneficial for hydrate stabilization.

Investigation on methane hydrate formation in silica gel particles below the freezing point

“…The reections at about 27.0 , 28.0 and 44.4 2q were assigned to the (320), (321) and (443) crystal planes of sI hydrate. 9,13,67 So the silica gel did not change the structure of methane hydrate. It can be seen from Fig.…”

High‐efficiency CO2 capture and separation based on hydrate technology: A review

“…To accelerate the hydrate formation rate and improve the CO 2 separation performance it is necessary to enhance the hydration kinetics. Typical kinetic promoters such as sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), cyclopentane, and lauryl alcohol ethoxylate (LAE) have been employed during the formation of CO 2 hydrate …”

“…Typical kinetic promoters such as sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), cyclopentane, and lauryl alcohol ethoxylate (LAE) have been employed during the formation of CO 2 hydrate. [66][67][68][69][70] Sodium dodecyl sulfate was reported to be one of the most effective kinetic promoters. Zhong and Rogers 71 claimed that SDS, as a carrier of gas molecules, could reduce surface tension, and decrease the equilibrium pressure in the aqueous phase.…”

Hydrate-Based Mild Separation of Lean-CH4/CO2 Binary Gas at Constant Pressure

“…It can significantly reduce the phase equilibrium conditions , and has high selectivity for CO 2 without reducing the separation factor. − Therefore, it is meaningful to use TBAB as a thermodynamic promoter for CH 4 /CO 2 separation. The literature studies , mention that using 5 wt % TBAB can increase CO 2 gas consumption. In addition, 5 wt % TBAB , may be the best concentration for carbon capture, and the separation effect at higher and lower concentration needs to be explored.…”