The chemistry of low dosage clathrate hydrate inhibitors

Abstract

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This review aims to introduce the chemistry of low dosage inhibitors of clathrate hydrate formation 5 within the context of their role in the oil and gas industry. The review covers both kinetic hydrate inhibitors and anti-agglomerants from the point of view of structure-function relationships, focussing on recent refinements in mechanistic understanding and chemical design, and the consequently evolving and increasingly fine-tuned properties of these fascinating compounds. Clathrate hydrates 10Clathrate hydrates are crystalline, non-stoichiometric host-guest compounds comprising a hydrogen bonded water framework, into which small molecular guest species such as methane are included within cavities formed by the water cages. Because there are no strong directional interactions between guest and host the 15 guests are free to vibrate and rotate but possess limited translational motion. 1 Typically common clathrate hydrates comprise 85 mol% water and 15 mol% guest(s) when all of the cavities are occupied.2 These materials form when the components are subjected to ambient temperatures (generally less 20 than 300 K) and moderate pressures (>0.6 MPa); conditions frequently found in oil and gas pipelines. 3 The initial reporting of gas hydrates is accredited to Sir Humphrey Davy in 1811, who focussed upon the crystallisation 25 of a cold aqueous solution of chlorine (known as oxymuriatic gas at the time). 4 In 1934 a pivotal report by Hammerschmidt acted as a catalyst for stimulating research in this area, by confirming that clathrate hydrates are responsible for the plugging of gas and oil pipelines and thereby dramatically increasing industrial 30 investment and research on the topic. 5 Today clathrate hydrates pose a major problem to the oil and gas industry with pipeline blockage causing many safety concerns in addition to requiring the shutdown of the pipeline for a time 35 whilst the plug is removed. This shutdown period results in reduced field site performance and may cause significant financial loss. Avoidance of pipeline shutdown is a priority to many oil and gas companies, and as such considerable investment is being made into research into clathrate hydrate inhibition to 40 circumvent such potentially catastrophic effects. Problems associated with gas hydrate formation reached the headlines in 2010 due to their destructive effects during BP's efforts to contain the oil spillage after the Deepwater Horizon blowout, thereby illustrating the importance of research in this area. While...

First investigation of modified poly(2-vinyl-4,4-dimethylazlactone)s as kinetic hydrate inhibitors

“…One of the methods to combat this problem is the use of kinetic hydrate inhibitors (KHIs) (Kelland, 2006;Kelland, 2011;Perrin et al, 2013). KHIs are one class of low dosage hydrate inhibitors (LDHIs) which, as the name implies, are added at low concentrations in the order of 0.5-2 wt.% as formulations in solvents.…”

N-Alkyl pyrrolidone ether podands as versatile alkali metal ion chelants

“…Reaction of compound 1 with NaPF 6 in acetonitrile followed by solvent evaporation after brief sonication to aid dissolution results in the isolation of three crystalline solids; two discrete complexes 10 of formulae [Na (1) 2 ]PF 6 (3) and [Na 3 (H 2 O) 2 (-1) 2 ](PF 6 ) 3 (4), and a coordination polymer {[Na 3 (µ 3 -1) 2 (µ 2 -1) 2 ](PF 6 ) 3 } n (5), with metal:ligand stoichiometry 1:2, 3:2 and 3:4, respectively. The product obtained is dependent primarily on the ratio of metal salt and ligand added and highlights the extremely versatile 15 coordination behaviour of ligand 1.…”

“…2 As a result, lactam 30 oligomers and polymers have remarkable properties, such as very high hydrophilicity (including water solubility), and high surface activity such that they find a range of applications, for example polyvinylpyrrolidone and polyvinylcaprolactam in the inhibition of gas hydrate crystallization in the oil industry. [3][4][5] Other 35 applications include uses in the pharmaceutical, cosmetic and detergent industries and in membranes, glue sticks, hot-melt adhesives, hydrogels and for crop protection. 2 The bis(pyrrolidone) derivative 1-{2-[2-(2-oxo-pyrrolid-1-yl)-ethoxy]-ethyl}-pyrrolid-2-one (1, Fig.…”

Janus effect of antifreeze proteins on ice nucleation

“…The contradiction also exists for the research of ice nucleation on solid surfaces immobilized with AFPs (12, 13). Therefore, it is highly desirable to elucidate the exact role of AFPs on ice nucleation and to correlate AFP structures at the molecular level with their function in tuning ice nucleation, which is essential for practical applications in food, pharmaceutical, and chemical industries (14,15).Herein, we investigate the effect of IBF and NIBF of AFPs on ice nucleation via binding AFPs to solid substrates in a way that either IBF or NIBF is exposed to liquid water. This binding method is readily extendable to other AFPs because of the clear distinction between IBF and NIBF; and IBFs of AFPs are relatively flat and often have a regular array of hydroxyl groups in comparison with the NIBFs (16, 17).…”

“…The contradiction also exists for the research of ice nucleation on solid surfaces immobilized with AFPs (12, 13). Therefore, it is highly desirable to elucidate the exact role of AFPs on ice nucleation and to correlate AFP structures at the molecular level with their function in tuning ice nucleation, which is essential for practical applications in food, pharmaceutical, and chemical industries (14,15).…”