Experimental evaluation of RAFT-based Poly(N-isopropylacrylamide) (PNIPAM) kinetic hydrate inhibitors

Park, Juwoon; Kim, Hyunho; Silveira, Kelly Cristine da; Sheng, Qi; Postma, Almar; Wood, Colin D.; Seo, Yutaek

doi:10.1016/j.fuel.2018.08.036

Cited by 30 publications

(16 citation statements)

References 34 publications

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“…The advantages of the route to make acrylamido-based KHI polymers from poly(acrylic acid) (PAA) include the simple two-stage synthesis procedure, the cheap starting material, and the fixed similar molecular weights of all the acrylamido products, thereby dismissing the molecular weight as an issue, and as a result, we can then better compare the functional groups. We focused on the acrylamido polymers with isopropyl, n -propyl, and pyrrolidinyl groups in this study, as those are the ones known to have the best KHI effect. ,− …”

Section: Resultsmentioning

confidence: 99%

A Simple and Direct Route to High-Performance Acrylamido-Based Kinetic Gas Hydrate Inhibitors from Poly(acrylic acid)

2020

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(Meth)acrylamido-based polymers are used commercially in kinetic hydrate inhibitor formulations to prevent gas hydrate formation in upstream oil and gas flow lines. The monomers used to make these polymers are relatively expensive. We have now synthesized a series of acrylamido-based polymers directly from low molecular weight poly(acrylic acid) (PAA) in a high-yield process, avoiding the use of expensive monomers. Cloud points of the polymers made from PAA were similar to the homopolymers made from the acrylamido monomers, indicating a good conversion from the acid to the amide group. Slow constant-cooling KHI screening tests were carried out on the new polymers in a series of steel rocking cells using a structure II-forming natural gas mixture. Poly(N-isopropylacrylamide), poly(N-(n-propyl) acrylamide), and polyacryloylpyrrolidine prepared directly from PAA all gave an excellent KHI performance, comparable to the homopolymers made from the acrylamido monomers. This direct synthesis method also allows for a very controlled comparison of the activity of the acrylamido functional groups because every polymer can be derived from the same PAA starting material. Thus, the number of monomer units in each homopolymer is kept constant. Conversion of the poly(methacrylic acid) or poly(methyl methacrylate) by the reaction with amines to give the methacrylamido polymers was not successful, probably due to the steric effect of the backbone methyl groups.

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Section: Resultsmentioning

confidence: 99%

A Simple and Direct Route to High-Performance Acrylamido-Based Kinetic Gas Hydrate Inhibitors from Poly(acrylic acid)

2020

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“…Homo/copolymers of cyclic amides are generally synthesized using conventional free-radical polymerization. ,,, Although any flask can be used as the polymerization reaction vessel, a Schlenk flask is typically used. ,− It has a side arm connected to a gas line that replaces the air (having the reactive oxygen) inside the flask with an inert gas like nitrogen for air-sensitive chemical reactions . The flask is immersed in a water bath and is generally fitted with a reflux condenser.…”

Section: Khis Based On Cyclic Amidesmentioning

confidence: 99%

“…The initial step is to mix the desired monomer to be polymerized with four to five times its weight with a solvent. , The solvents generally used are organic solvents like propanol, , ethanol, dioxane, ,,− or dimethylformamide. − Subsequently, 1–20 wt % of the radical initiator is added. The radical initiator in most cases is 2,2′-azobis (2-methylpropionitrile) (AIBN). ,,,− After that, because the presence of oxygen is detrimental to the reaction, , the system is degassed and sealed under the protection of nitrogen. , Procedures like the freeze–pump–thaw method , or a high vacuum line are used for the degassing process. The freeze–pump–thaw method is more efficient; , however, a high vacuum line is commonly used because of its simplicity. , The reaction mixture is then vigorously stirred at 800–1000 rpm, ,, preferably using a magnetic stirrer at high temperatures between 60 and 80 °C for 16–20 h − for the monomer molecules to polymerize.…”

Section: Khis Based On Cyclic Amidesmentioning

confidence: 99%

Review of Kinetic Hydrate Inhibitors Based on Cyclic Amides and Effect of Various Synergists

Singh

Suri

2021

Energy Fuels

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This Review presents a comprehensive literature review of an important class of kinetic hydrate inhibitors (KHIs) that is based on cyclic amides (lactams). The major aspects of the KHIs, such as their synthesis, inhibition mechanism, toxicity, biodegradability, performance, and cloud point, are thoroughly discussed. Data for 70 KHIs made of homo/co/terpolymers from 330 experiments are collected and evaluated for performance. The effects of the inhibitor concentration, molecular weight, monomer ratio of the co/terpolymers, and 35 different synergist chemicals on various KHIs are also studied. In conclusion, the top 10 KHIs with the highest performances that had a cloud point above 70 °C are presented. The copolymer (1:1) N-vinylpyrrolidone/N-vinyl-caprolactam (VP/VCap) is found to have the highest induction time (IT) of 13 to 14 h at 0.25 wt % and at a cooling rate of 1 °C/h. Some KHIs like Inhibex BIO-800 and poly(N-vinyl azacyclooctanone) (PVACO) also have a very high ITs (17 and 13.5 h, respectively) at 0.25 wt % and at a cooling rate of 1 °C/h, but they have low cloud points (<25 °C). Guanidinium salts (n-Bu6GuanCl/n-Bu6GuanBr) and a phosphonium salt, (n-Pe)4PBr, are found to be the best synergists for the cyclic-amide-based KHIs. When used at 0.15 to 0.30 wt % along with the KHIs, they further increase the IT by 3–5 h.

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“…This level of dosing is accompanied by environmental and economical issues. In view of this, application of “low-dosage hydrate inhibitors” has become a research hotspot. − Such inhibitors, e.g., poly( N -vinyl caprolactam) [PVCap, International Union of Pure and Applied Chemistry (IUPAC) name of poly(1-ethenylazepan-2-one)], and poly( N -vinylpyrrolidone) [PVP, IUPAC name of poly(1-ethenylpyrrolidin-2-one)], have an excellent kinetic inhibition effect and unique solution properties. − Up to now, the majority of studies on the kinetic hydrate inhibitors have focused on mixtures with synergists and other kinetic or thermodynamic inhibitors or copolymer formation to achieve different amphiphilicity or cloud point transition temperatures. − …”

Section: Introductionmentioning

confidence: 99%

Dependence of the Kinetic Hydrate Inhibition Effect of Poly(N-vinylpyrrolidone) upon the Molecular Weight Is Influenced by Water Mobility in Millisecond Dynamics

Laroui

et al. 2020

Energy Fuels

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Explosive formation of a natural gas clathrate hydrate in production lines has been a technical bottleneck in ocean field natural gas drilling and gas transport. To mitigate this problem, polymer inhibitors can be used as a low-dosage kinetic inhibitor during operation. Key factors affecting the physicochemical performance of a benchmark inhibitor, poly(N-vinylpyrrolidone) (PVP),are not yet completely known. It is found here that the ability of PVP to delay the rapid crystal growth of the clathrate hydrate is correlated to the surrounding water dynamics. PVP can produce immobilized non-freezable water molecules with fast transverse relaxation on a sub-millisecond to millisecond time scale as revealed by nuclear magnetic resonance relaxometry. The unique water dynamics are also determined as a form of non-freezable bound water measured by differential scanning calorimetry. Changes in the molecular weight of PVP lead to changes in the entire inhibition time before the rapid growth of the hydrate crystals, and an optimal size of the PVP chain is found for the best inhibition. The hydrate crystallization rate constants are lowered by 1−2 orders of magnitude when the PVP chains have near the optimal size, further providing an explanation of the chain length dependence of the inhibition time.

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Experimental evaluation of RAFT-based Poly(N-isopropylacrylamide) (PNIPAM) kinetic hydrate inhibitors

Cited by 30 publications

References 34 publications

A Simple and Direct Route to High-Performance Acrylamido-Based Kinetic Gas Hydrate Inhibitors from Poly(acrylic acid)

A Simple and Direct Route to High-Performance Acrylamido-Based Kinetic Gas Hydrate Inhibitors from Poly(acrylic acid)

Review of Kinetic Hydrate Inhibitors Based on Cyclic Amides and Effect of Various Synergists

Dependence of the Kinetic Hydrate Inhibition Effect of Poly(N-vinylpyrrolidone) upon the Molecular Weight Is Influenced by Water Mobility in Millisecond Dynamics

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