An investigation into the kinetic hydrate inhibitor properties of two imidazolium-based ionic liquids on Structure II gas hydrate

Villano, Luca Del; Kelland, Malcolm A.

doi:10.1016/j.ces.2010.06.033

Cited by 106 publications

(78 citation statements)

References 14 publications

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“…Such affinity between KHIs and the formed hydrate particles prevents water molecules from approaching the formed hydrate (and allowing it to grow bigger) and significantly retards the blockage problem even under hydrate-forming conditions. There are also reports of a few ionic liquids that act as dual function inhibitors (playing both thermodynamic and kinetic inhibition roles) [14][15][16][17]. Basically, a dual function inhibitor is designed to improve inhibiting performance by playing two inhibition roles.…”

Section: Introductionmentioning

confidence: 99%

Anti-Agglomeration Effects of Biodegradable Surfactants from Natural Sources on Natural Gas Hydrate Formation

Kang

Lee

2020

Energies

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Kinetic hydrate inhibitors (KHI) and anti-agglomerants (AA) rather than thermodynamic hydrate inhibitors (THI) are often used for flow assurance in pipelines. This is because they require much lower dosages than thermodynamic inhibitors. Although the hydrate-phase equilibria are not affected, KHI and AA prevent the formed hydrate crystals from growing to a bulky state causing pipeline blockage. However, these KHIs might have huge environmental impact due to leakages from the pipelines. In this study, two biodegradable AA candidates from natural sources (that is, lecithin and lanolin) are proposed and their performances are evaluated by comparing them with and without a conventional AA (Span 80, sorbitan monooleate). At 30% and 50% water cut, the addition of AA materials was found to enhance the flow characteristics substantially in pipelines and hardly affected the maximum value of the rotational torque, respectively. Considering the cost-effective and environmental advantages of the suggested AA candidates over a conventional AA such as Span 80, the materials are thought to have potential viability for practical operation of oil and gas pipelines. However, additional investigations will be done to clarify the optimum amounts and the action mechanisms of the suggested AAs.

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Section: Introductionmentioning

confidence: 99%

Anti-Agglomeration Effects of Biodegradable Surfactants from Natural Sources on Natural Gas Hydrate Formation

Kang

Lee

2020

Energies

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“…Others besides Shell have also confirmed the THF hydrate growth inhibition properties of TBAB. 5,6 Bis-quaternary and polyquaternary ammonium salts have also been studied as tetrahydrofuran hydrate crystal growth inhibitors. 7 Quaternary salts in these classes have been used in two ways to control gas hydrate formation in the upstream oil and gas industry in low dosage hydrate inhibitor formulations: as synergists for kinetic hydrate inhibitor polymers 8−14 and as antiagglomerants when modified into surfactants.…”

Section: ■ Introductionmentioning

confidence: 99%

Tetra(iso-hexyl)ammonium Bromide—The Most Powerful Quaternary Ammonium-Based Tetrahydrofuran Crystal Growth Inhibitor and Synergist with Polyvinylcaprolactam Kinetic Gas Hydrate Inhibitor

2012

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Tetraalkylammonium salts, particularly with several n-butyl or n-pentyl or iso-pentyl groups, have previously been shown to be excellent structure II (SII) gas and tetrahydrofuran (THF) hydrate crystal growth inhibitors. We have investigated the ability of quaternary ammonium salts with isoalkyl groups with 5 to 7 carbons atoms to inhibit the growth of tetrahydrofuran (THF) hydrate crystal. Two new quaternary salts were synthesized for the first time: tetra(iso-hexyl)ammonium bromide (TiHexAB) and tetra(iso-heptyl)ammonium bromide (TiHepAB). It was found that tetra(iso-pentyl)ammonium bromide (TiPeNB) gave poorer crystal growth inhibition than isomeric tetra(n-pentyl)ammonium bromide (TPAB) but similar performance to tetra(n-butyl)ammonium bromide (TBAB). However, TiHexAB gave better inhibition than any quaternary ammonium previously reported, including TPAB. TiHepAB was a poorer THF hydrate crystal growth inhibitor, similar in performance to isomeric tetra(n-hexyl)ammonium bromide. We believe the reason for these results is related to the optimal length of the n-alkyl/isoalkyl groups and the improved van der Waals interaction with open SII hydrate cages with the isoalkyl branching at the end of the chains, compared to a straight alkyl chain. The superior inhibition performance of TiHexAB was illustrated by testing its ability as a synergist for the well-known kinetic hydrate inhibitor (KHI) polyvinylcaprolactam (PVCap). In high pressure rocking cell tests using a SII-forming natural gas mixture, TiHexAB clearly outperformed TBAB, TPAB, and all the other quaternary ammonium salts tested. In addition, tetra(n-hexyl)ammonium bromide (THexAB) gave KHI synergism with PVCap superior to that of TBAB, even though TBAB was a better THF hydrate crystal growth inhibitor. We speculate that adsorption onto hydrate crystal surfaces may not be the only synergistic mechanism operating and that the more hydrophobic THexAB is perturbing the nucleation of hydrate more than the less hydrophobic TBAB. In addition, it was investigated whether replacing a carbon atom with an oxygen atom (ether linkage) in the alkyl chains of TPAB would affect the THF hydrate crystal growth inhibition. Thus, tetra(alkoxyethyl)ammonium bromides were prepared for the first time where the alkoxy group is ethoxy or methoxy. Both of these quaternary ammonium salts gave negligible THF hydrate crystal growth inhibition. ■ INTRODUCTIONIt has been known for about two decades that certain onium salts (quaternary ammonium and phosphonium salts) are capable of perturbing and inhibiting the growth of structure II (SII) clathrate hydrates. 1−4 Shell, the oil and energy company, was the first to discover this fact from tests with a study on SII tetrahydrofuran (THF) hydrates. The most active inhibitors of THF hydrate were found to have either n-butyl, n-pentyl, or iso-pentyl groups on the quaternary N or P atom (Figure 1). Shell's patents on this subject also cover sulphonium salts, which can have a maximum of three alkyl groups attached to the sulfur atom, althoug...

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“…Compared to some traditional gas consumption evaluations of KHIs, in which hydrate formation can be evaluated only at a single subcooling, with a single experiment, the 3‐in‐1 technique allowed hydrate film growth rates to be evaluated under several subcoolings in the presence of commercial inhibitors. Additionally, the traditional screening of KHI is time‐consuming with experimental times that can be from 10 hours to several days of experimentation per datum and under only one driving force . Many KHI performance studies still rely on induction times, which explain, in part, the long experimental times.…”

Section: Resultsmentioning

confidence: 99%

“…Additionally, the traditional screening of KHI is time-consuming with experimental times that can be from 10 hours to several days of experimentation per datum and under only one driving force. [10][11][12][13]28,29] Many KHI performance studies still rely on induction times, which explain, in part, the long experimental times. Nonetheless, measuring growth rates from systems with hydrate history, such as we have done here, has been proven to be reproducible and to overcome many limitations of the induction time-based approaches.…”

Section: Kinetics and Growthmentioning

confidence: 99%

Assessment of commercial hydrate inhibitors using the 3‐in‐1 method

et al. 2019

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Phase equilibria, kinetics, and morphology studies of gas hydrates require separate pieces of equipment and experimentation times in the order of days. Recently, we designed a reactor that allows for tight control of the crystallization temperature. Coupled with a novel method, this reactor can screen the crystal morphology, phase equilibria, and apparent kinetics of gas hydrates. Compared to traditional multi‐trial methods, the main advantage of this method is that only a single experiment, completed in the order of hours, is required to assess: (a) the change in hydrate growth velocity with respect to temperature, (b) the HLV equilibrium temperature at the experimental pressure, and (c) the change in crystal morphology with respect to driving force. Using this 3‐in‐1 method, methane hydrate growth and dissociation was studied in the presence of four commercial inhibitors. Phase equilibria, kinetics, and morphology were obtained for all hydrate systems with inhibitors. The standard uncertainty for the HLV equilibrium temperature was 0.05 K and for pressure 0.005 MPa. The apparent rates of growth were measured for all systems (standard uncertainty was 0.008 mm · s−1) and the difference between the inhibited systems and the pure system was very clear. Crystal habits varied considerably among inhibitors and radically with respect to the uninhibited system. Overall, we present an innovative technology to assess the morphology, kinetics, and thermodynamics of hydrate forming systems with a single apparatus. Furthermore, with little time investment, small sample sizes can be used to obtain replicates with minimum temperature and pressure uncertainties.

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An investigation into the kinetic hydrate inhibitor properties of two imidazolium-based ionic liquids on Structure II gas hydrate

Cited by 106 publications

References 14 publications

Anti-Agglomeration Effects of Biodegradable Surfactants from Natural Sources on Natural Gas Hydrate Formation

Anti-Agglomeration Effects of Biodegradable Surfactants from Natural Sources on Natural Gas Hydrate Formation

Tetra(iso-hexyl)ammonium Bromide—The Most Powerful Quaternary Ammonium-Based Tetrahydrofuran Crystal Growth Inhibitor and Synergist with Polyvinylcaprolactam Kinetic Gas Hydrate Inhibitor

Assessment of commercial hydrate inhibitors using the 3‐in‐1 method

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