First Investigation of the Kinetic Hydrate Inhibitor Performance of Poly(<i>N</i>-alkylglycine)s

Reyes, Fernando T.; Guo, Li; Hedgepeth, John; Zhang, Donghui; Kelland, Malcolm A.

doi:10.1021/ef501779p

Cited by 40 publications

(81 citation statements)

References 34 publications

(53 reference statements)

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“…8000) and with poly-(vinylcaprolactam) (PVCap, M n = 4000). 33 Table 3 as an average of 8−10 identical parallel tests of the desired polymer. A comparison between T o values for this family of polymers is given in Figure 13.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Kinetic Hydrate Inhibitors: Structure–Activity Relationship Studies on a Series of Branched Poly(ethylene citramide)s with Varying Lipophilic Groups

et al. 2015

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Novel citric-acid-based polyamides were synthesized by polycondensation reactions using tributyl citrate (TBC) and ethylene diamine (EDA), producing hyperbranched poly(ethylene citramide)s with NH 2 termini, which were functionalized with isopropyl, n-butyl, and cyclohexyl groups via the urea group. Characterization was carried out by 1 H and 13 C nuclear magnetic resonance (NMR) spectroscopic techniques. Molecular weights in this polymer family varied from 3000 to 10 000 Da. The activity of this polymer family as gas hydrate kinetic inhibitors (KHIs) was evaluated for the first time. Constant cooling (1°C /h) experiments were carried out in high-pressure steel rocking cells using a synthetic natural gas that preferentially forms structure II gas hydrates. The best KHI performance was given by poly(ethylene citramide) CONHCyHe with pendant Ncyclohexyl groups (M n = 5.65 × 10 3 , and M w = 1.14 × 10 4 ). A structure−activity relationship (SAR) analysis of the KHI test results supports the hypothesis that increasing the size of the lipophilic groups increases the KHI performance as long as water solubility is maintained through hydrogen bonding via the amide and/or urea functional groups.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Kinetic Hydrate Inhibitors: Structure–Activity Relationship Studies on a Series of Branched Poly(ethylene citramide)s with Varying Lipophilic Groups

et al. 2015

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“…Also, for comparative purposes we used our standard slow constant cooling (SCC) test method. 27 The pressure was approximately 76 bar at the start of each SCC experiment. At this pressure, an average equilibrium temperature ( T eq ) of 20.2 °C ± 0.05 °C was obtained from five repeat tests by laboratory slow dissociation experiments in the same rocking cells.…”

Section: Methodsmentioning

confidence: 99%

Nonpolymeric Citramide-Based Kinetic Hydrate Inhibitors: Good Performance with Just Six Alkylamide Groups

Ghosh

Kelland

2022

ACS Omega

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The use of kinetic hydrate inhibitors (KHIs) is a well-known method for preventing gas hydrate formation in oil and gas production flow lines. The main ingredient in KHI formulations is one or more polymers with amphiphilic groups. Here, we report a series of citramide-based nonpolymeric KHIs. The KHI performance of these citramide derivatives has been studied using a synthetic natural gas mixture (forming structure II hydrate as the thermodynamically preferred phase) in slow constant cooling (ca. 1 °C/h starting from 20.5 °C) high-pressure (76 bar) rocking cell experiments. Isobutyl-substituted alkyl chains in the mono/bis(trialkyl citric acid) amide derivative gave better KHI performance than n -propyl-substituted citramide derivatives. Moreover, biscitramides with six alkylamide functional groups gave better performance than the equivalent monocitramides with three alkylamide groups. A solution of 2500 ppm of bis(tributyl citric acid) amide gave an average gas hydrate onset temperature ( T o ) of 8.4 °C compared to 8.9 °C for a low molecular weight N -vinyl pyrrolidone/ N -vinyl caprolactam 1:1 copolymer. For the bis(tributyl citric acid) amide, addition of liquid hydrocarbon ( n -decane) lowered further the average T o value to 6.2 °C, although this is at least partly due to lowering of the hydrate equilibrium temperature. This study demonstrates that good KHI performance can be obtained from molecules with as little as six amphiphilic alkylamide groups.

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“…This is satisfactorily close to the experimental value of 284 K. 89−91 We choose PVCap in this study among many KHIs 23,24 because it is a high-performance KHI and has been frequently used as a standard KHI in experimental studies. 24,26,29,30,[35][36][37][38][39]44,52,53 This KHI has also often been investigated in simulation studies. 58,62,63,65 The parameters for the intramolecular interactions and the Lennard-Jones interactions of PVCap are taken from the OPLS-AA model.…”

Section: ■ Computational Detailsmentioning

confidence: 99%

Adsorption of Kinetic Hydrate Inhibitors on Growing Surfaces: A Molecular Dynamics Study

2017

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We investigate the mechanism of a typical kinetic hydrate inhibitor (KHI), polyvinylcaprolactam (PVCap), which has been applied to prevent hydrate plugs from forming in gas pipe lines, using molecular dynamics simulations of crystal growth of ethylene oxide hydrate. Water-soluble ethylene oxide is chosen as a guest species to avoid problems associated with the presence of the gas phase in the simulation cell such as slow crystal growth. A PVCap dodecamer adsorbs irreversibly on the hydrate surface which grows at supercooling of 3 K when the hydrophobic part of two pendent groups are trapped in open cages at the surface. The amide hydrogen bonds make no contribution to the adsorption. PVCap can adsorb on various crystallographic planes of sI hydrate. This is in contrast to antifreeze proteins, each of which prefers a specific plane of ice. The trapped PVCap gives rise to necessarily the concave surface of the hydrate. The crystal growth rate decreases with increasing surface curvature, indicating that the inhibition by PVCap is explained by the Gibbs-Thomson effect.

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First Investigation of the Kinetic Hydrate Inhibitor Performance of Poly(N-alkylglycine)s

Cited by 40 publications

References 34 publications

Kinetic Hydrate Inhibitors: Structure–Activity Relationship Studies on a Series of Branched Poly(ethylene citramide)s with Varying Lipophilic Groups

Kinetic Hydrate Inhibitors: Structure–Activity Relationship Studies on a Series of Branched Poly(ethylene citramide)s with Varying Lipophilic Groups

Nonpolymeric Citramide-Based Kinetic Hydrate Inhibitors: Good Performance with Just Six Alkylamide Groups

Adsorption of Kinetic Hydrate Inhibitors on Growing Surfaces: A Molecular Dynamics Study

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