Kinetics of Hydrate Formation in the CO₂+TBAB+H₂O System at Low Mass Fractions

Abstract

In the present study, CO 2 gas and tetra-n-butyl ammonium bromide (TBAB) is adopted to form CO 2 +TBAB double hydrate at mass fractions w = 0.05 and 0.10. The moles of CO 2 +TBAB double hydrate are calculated by the variation of pressure of CO 2 gas from initial pressure at about 4.03 MPa and the solubility of CO 2 in TBAB aqueous solution at various subcoolings of 2.0−5.0 K. In addition, the formation characteristics of CO 2 +TBAB double hydrate are observed by the visualization, and it is verified to be a type B double hydrate. The kinetics of CO 2 +TBAB double hydrate formation at w = 0.05 and 0.10 is determined by the normalized rate of hydrate formation in the hydration process.

Review of Morphology Studies on Gas Hydrate Formation for Hydrate-Based Technology

“…The thermodynamic promoters could actively take part in the hydrate formation and shift the phase boundary to a milder region (higher temperature and lower pressure conditions), with a more stable hydrate structure. The thermodynamic promoters commonly used in laboratories include tetrahydrofuran (THF), cyclopentane (CP), and quaternary ammonium/phosphonium salts . It is known that THF and CP can form structure II (sII) hydrates under atmospheric pressure and at moderately low temperatures.…”

“…It was also found that a system with agitation or with a continuous supply of gas could strongly influence the dissolution rate of the gas, thus affecting the gas mass-transfer mechanism and promoting the crystal growth in the liquid phase. In the agitation system, a better heat exchange and perturbation would be favorable for nucleation to increase the number of crystals and decrease the size . When CO 2 was continuously supplied, the shapes of the hydrate crystals were similarly polygonal flat-plate, columnar crystals and dendritic crystals as Δ T sub increased .…”

Kinetics of (TBAF + CO2) semi-clathrate hydrate formation in the presence and absence of SDS

“…Despite a large number of studies undertaken on the thermodynamics of semi-clathrate hydrates, few attempts have been made to investigate the kinetics of this type of hydrates (Fan et al 2011;Ye et al 2014).…”

Investigation of kinetics of tetrabutylammonium chloride (TBAC) + CH4 semiclathrate hydrate formation

“…Thus this kind of ionic clathrate hydrate, known as semiclathrate hydrate (SCH), shows many special features, such as cohost inclusion and improved thermal stability, due to the ionic interaction between host and guest molecules. 6 Recently, SCH has been studied as a more promising medium as compared with ordinary clathrate hydrate for many engineering practices, such as gas separation/ storage/transportation, [7][8][9][10][11][12][13][14][15][16][17][18][19][20] seawater desalination, 21 and cold energy storage. [22][23][24][25] SCHs of TBAX (X ¼ F/Cl/Br) were rst founded by Fowler et al 26 in 1940 and structurally determined by Jeffery 27 in 1969.…”

“…In 2013, Roosta et al 36 reported that TBAB could increase the CH 4 hydrate formation rate. In 2014, Zhang et al 14 studied the formation kinetics of (TBAB + CO 2 ) SCHs at mass fraction ¼ (0.05 and 0.10), and the results revealed that the moles of formed SCHs and the formation rates both increased with the increase of subcooling degree. In 2016, Verrent et al 37 investigated the hydrate growth of (TBAB + CO 2 ) at 0.40 salt mass fraction.…”