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| '''Clathrate hydrates''' (or ''gas clathrates'', ''gas hydrates'', ''clathrates'', ''hydrates'', etc.) | | This is a preview for the new '''MathML rendering mode''' (with SVG fallback), which is availble in production for registered users. |
| are [[crystal]]line water-based [[solid]]s physically resembling [[ice]], in which small [[Chemical polarity|non-polar]] [[molecule]]s (typically [[gas]]es) or [[Chemical polarity|polar]] molecules with large hydrophobic moieties are trapped inside "cages" of [[hydrogen bond]]ed [[water (molecule)|water molecules]]. In other words, clathrate hydrates are [[clathrate compounds]] in which the host molecule is [[water]] and the guest molecule is typically a gas or liquid. Without the support of the trapped molecules, the [[Crystal structure|lattice]] structure of hydrate clathrates would collapse into conventional ice crystal structure or liquid water. Most low molecular weight gases (including {{oxygen}}<sub>2</sub>, {{hydrogen}}<sub>2</sub>, {{nitrogen}}<sub>2</sub>, [[carbon dioxide|CO<sub>2</sub>]], [[methane|CH<sub>4</sub>]], [[hydrogen sulfide|H<sub>2</sub>S]], {{argon}}, {{krypton}}, and {{xenon}}), as well as some higher [[hydrocarbon]]s and [[freon]]s will form [[hydrate]]s at suitable temperatures and pressures. Clathrate hydrates are not chemical compounds as the sequestered molecules are never bonded to the lattice. The formation and decomposition of clathrate hydrates are [[Phase_transition#Classification_of_phase_transitions|first order phase transitions]], not chemical reactions. Their detailed formation and decomposition mechanisms on a molecular level are still not well understood.<ref>{{cite journal | author = Gao S | coauthors = House W, Chapman WG | year = 2005 | title = NMR MRI Study of Gas Hydrate Mechanisms | volume = 109 | pages = 19090–19093 | publisher = American Chemical Society | doi = 10.1021/jp052071w | url = http://www.scribd.com/doc/9701479/NMR-MRI-Study-of-Gas-Hydrate-Mechanisms | accessdate = August 3, 2009 | pmid = 16853461 | last1 = Gao | first1 = S | last2 = House | first2 = W | last3 = Chapman | first3 = WG | issue = 41 | journal = The journal of physical chemistry. B }}</ref><ref>{{cite journal | author = Gao S | coauthors = Chapman WG, House W | year = 2005 | title = NMR and Viscosity Investigation of Clathrate Formation and Dissociation | journal = Ind.Eng.Chem.Res. | volume = 44 | pages = 7373–7379 | publisher = Americal Chemical Society | doi = 10.1021/ie050464b | url = http://www.scribd.com/doc/9701466/NMR-and-Viscosity-Investigation-of-Clathrate-Formation-and-Dissociation | accessdate = August 3, 2009 | issue = 19 }}</ref>
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| Clathrate hydrates were first documented in 1810 by Sir [[Humphry Davy]].<ref>{{cite web |url=http://ethomas.web.wesleyan.edu/ees123/clathrate.htm |title=Clathrates: little known components of the global carbon cycle |accessdate=13 December 2007 |year=2004 |month=November |author=Ellen Thomas |publisher=Wesleyan University }}</ref>
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| Clathrates have been found to occur naturally in large quantities. Around 6.4 trillion (i.e. 6.4x10<sup>12</sup>) tonnes of [[methane]] is trapped in deposits of [[methane clathrate]] on the deep [[ocean floor]].<ref>{{Cite paper | first = B. | last = Buffett | first2 = D. | last2 = Archer | title = Global inventory of methane clathrate: sensitivity to changes in the deep ocean | year = 2004 | pages = 185–199 | journal = Earth Planet. Sci. Lett. |doi=10.1016/j.epsl.2004.09.005 | bibcode=2004E%26PSL.227..185B}}</ref> Such deposits can be found on the [[Norwegian continental shelf]] in the northern headwall flank of the [[Storegga Slide]]. Clathrates can also exist as [[permafrost]], as at the [[Mallik gas hydrate field]] in the [[Mackenzie River|Mackenzie Delta]] of northwestern [[Canadian Arctic]]. These natural gas hydrates are seen as a potentially vast energy resource, but an economical extraction method has so far proven elusive. [[Hydrocarbon]] clathrates cause problems for the petroleum industry, because they can form inside [[Pipeline transport|gas pipelines]] often resulting in plug formation. Deep sea deposition of [[carbon dioxide clathrate]] has been proposed as a method to remove this [[greenhouse gas]] from the atmosphere and control [[climate change]].
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| Clathrates are suspected to occur in large quantities on some outer [[planet]]s, [[natural satellite|moons]] and [[trans-Neptunian object]]s, binding gas at fairly high temperatures.
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| == Structure == | | '''MathML''' |
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| [[Image:HydrateStructures.jpg|thumb|200px|Cages building the different gas hydrate structures.]]
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| Gas hydrates usually form two [[Crystallography|crystallographic]] cubic structures – structure (Type) I and structure (Type) II<ref>von Stackelberg, M. & Müller, H. M. (1954) ''Zeitschrift für Elektrochemie'' '''58''', 1, 16, 83</ref> of space groups <math>Pm\overline{3}n</math> and <math>Fd\overline{3}m</math> respectively. Seldom, a third hexagonal structure of space group <math>P6/mmm</math> may be observed (Type H).<ref>Sloan E. D., Jr. (1998) Clathrate hydrates of natural gases. Second edition, Marcel Dekker Inc.:New York.</ref>
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| The unit cell of Type I consists of 46 water molecules, forming two types of cages – small and large. The small cages in the unit cell are two against six large ones. The small cage has the shape of a pentagonal [[dodecahedron]] (5<sup>12</sup>) and the large one that of a [[tetradecahedron]], specifically a [[hexagonal truncated trapezohedron]] (5<sup>12</sup>6<sup>2</sup>), together forming a [[Weaire-Phelan structure]]. Typical guests forming Type I hydrates are [[carbon dioxide|CO<sub>2</sub>]] in [[carbon dioxide clathrate]] and [[methane|CH<sub>4</sub>]] in [[methane clathrate]].
| | <span style="color: red">Follow this [https://en.wikipedia.org/wiki/Special:Preferences#mw-prefsection-rendering link] to change your Math rendering settings.</span> You can also add a [https://en.wikipedia.org/wiki/Special:Preferences#mw-prefsection-rendering-skin Custom CSS] to force the MathML/SVG rendering or select different font families. See [https://www.mediawiki.org/wiki/Extension:Math#CSS_for_the_MathML_with_SVG_fallback_mode these examples]. |
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| The unit cell of Type II consists of 136 water molecules, forming also two types of cages – small and large. In this case the small cages in the unit cell are sixteen against eight large ones. The small cage has again the shape of a pentagonal dodecahedron (5<sup>12</sup>) but the large one is a [[hexadecahedron]] (5<sup>12</sup>6<sup>4</sup>). Type II hydrates are formed by gases like O<sub>2</sub> and N<sub>2</sub>.
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| The unit cell of Type H consists of 34 water molecules, forming three types of cages – two small of different type and one huge. In this case, the unit cell consists of three small cages of type 5<sup>12</sup>, twelve small ones of type 4<sup>3</sup>5<sup>6</sup>6<sup>3</sup> and one huge of type 5<sup>12</sup>6<sup>8</sup>. The formation of Type H requires the cooperation of two guest gases (large and small) to be stable. It is the large cavity that allows structure H hydrates to fit in large molecules (e.g. [[butane]], [[hydrocarbon]]s), given the presence of other smaller help gases to fill and support the remaining cavities. Structure H hydrates were suggested to exist in the Gulf of Mexico. Thermogenically-produced supplies of heavy hydrocarbons are common there.
| | Here are some [https://commons.wikimedia.org/w/index.php?title=Special:ListFiles/Frederic.wang demos]: |
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| == Hydrates in the Universe ==
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| Iro ''et al.'',<ref>{{cite journal | last1 = Iro | first1 = N. | last2 = Gautier | first2 = D. | last3 = Hersant | first3 = F. | last4 = Bockelée-Morvan | first4 = D. | last5 = Lunine | first5 = J. I. | year = 2003 | title = An interpretation of the Nitrogen deficiency in comets | url = | journal = Icarus | volume = 161 | issue = 2| page = 513 |bibcode=2003Icar..161..511I |doi=10.1016/S0019-1035(02)00038-6 }}</ref> trying to interpret the [[nitrogen]] deficiency in [[comet]]s, stated most of the conditions for hydrate formation in the [[Protoplanetary disk|protoplanetary nebulae]], surrounding the [[Main sequence|pre-main and main sequence]] stars were fulfilled, despite the rapid grain growth to meter scale. The key was to provide enough microscopic ice particles exposed to a gaseous environment. Observations of the [[Radiometry|radiometric]] [[Continuum (theory)|continuum]] of [[Protoplanetary disk|circumstellar discs]] around <math>\tau</math>[[T Tauri star|-Tauri]] and [[Herbig Ae/Be stars]] suggest massive dust disks consisting of millimeter-sized grains, which disappear after several million years (e.g.,<ref>{{cite journal | last1 = Beckwith | first1 = S. V. W. | last2 = Henning | first2 = T. | last3 = Nakagawa | first3 = Y. | year = 2000 | title = Dust properties and assembly of large particles in protoplanetary disks | url = | journal = Protostars and Planets | volume = IV | issue = | page = 533 | arxiv=astro-ph/9902241 }}</ref><ref>{{cite journal | last1 = Natta | first1 = A. | last2 = Grinin | first2 = V. | last3 = Mannings | first3 = V. | year = 2000 | title = Properties and Evolution of Disks around Pre-Main-Sequence Stars of Intermediate Mass | url = | journal = Protostars and Planets | volume = IV | issue = | page = 559 |id={{hdl|2014/17884}} }}</ref>). A lot of work on detecting water ices in the Universe was done on the [[Infrared Space Observatory]] (ISO). For instance, broad [[Spectral bands|emission bands]] of water ice at 43 and 60 μm were found in the disk of the isolated [[Herbig Ae/Be stars|Herbig Ae/Be star]] HD 100546 in [[Musca]]. The one at 43 μm is much weaker than the one at 60 μm, which means the water ice, is located in the outer parts of the disk at temperatures below 50 K.<ref>{{cite journal | bibcode = 1998A&A...332L..25M | author=Malfait, K., Waelkens, C., Waters, L. B. F. M., Vandenbussche, B., Huygen, E. & de Graauw, M. S. |year=1998 |title= The spectrum of the young star HD 100546 observed with the Infrared Space Observatory |journal=Astron. Astrophys.|volume=332 |pages= L25–L28 | last2 = Waelkens | last3 = Waters | last4 = Vandenbussche | last5 = Huygen | last6 = De Graauw}}</ref> There is also another broad ice feature between 87 and 90 μm, which is very similar to the one in [[NGC 6302]] <ref>Barlow, M.J., In the proceedings of ‘ISO’s view on stellar evolution’, Noordwijkerhout, July, 1-4, 1997</ref> (the Bug or Butterfly nebula in [[Scorpius]]). Crystalline ices were also detected in the proto-planetary disks of [[Epsilon Eridani|ε-Eridani]] and the isolated Fe star HD 142527<ref>{{cite journal | title= Modeling the infrared emission from the ε-Eridani disk| doi = 10.1086/380495 | year= 2003 | last1= Li | first1= Aigen | last2= Lunine | first2= J. I. | last3= Bendo | first3= G. J. | journal= The Astrophysical Journal | volume= 598 | pages= L51–L54 | bibcode=2003ApJ...598L..51L}}</ref><ref>{{cite journal | last1 = Malfait | first1 = K. | last2 = Waelkens | first2 = C. | last3 = Bouwman | first3 = J. | last4 = De Koter | first4 = A. | last5 = Waters | first5 = L. B. F. M. | year = 1999 | title = The ISO spectrum of the young star HD 142527 | url = | journal = Astron. Astrophys | volume = 345 | issue = | page = 181 |bibcode=1999A&A...345..181M}}</ref> in [[Lupus (constellation)|Lupus]]. 90 % of the ice in the latter was found crystalline at temperature around 50 K. [[Hubble Space Telescope|HST]] demonstrated that relatively old [[Protoplanetary disk|circumstellar disks]], as the one around the 5 million year old B9.5Ve<ref>Jaschek, C. & Jaschek, M. (1992) ''Astron. Astrophys.'', '''95''', p. 535</ref> [[Herbig Ae/Be stars|Herbig Ae/Be star]] HD 141569A, are dusty.<ref>{{cite journal | last1 = Clampin | first1 = M. | year = 2003 | title = Hubble Space Telescope ACS Coronagraphic Imaging of the Circumstellar Disk around HD 141569A | url = | journal = Astron. J. | volume = 126 | issue = | pages = 385–392 | doi = 10.1086/375460 | last2 = Krist | first2 = J. E. | last3 = Ardila | first3 = D. R. | last4 = Golimowski | first4 = D. A. | last5 = Hartig | first5 = G. F. | last6 = Ford | first6 = H. C. | last7 = Illingworth | first7 = G. D. | last8 = Bartko | first8 = F. | last9 = Bentez | first9 = N. | bibcode=2003AJ....126..385C}}</ref> Li & Lunine<ref>{{cite journal | last1 = Li | first1 = A. | last2 = Lunine | first2 = J. I. | year = 2003 | title = Modeling the infrared emission from the HD 141569A disk | url = | journal = Astrophys. J. | volume = 594 | issue = 2| pages = 987–1010 | doi = 10.1086/376939 | bibcode=2003ApJ...594..987L}}</ref> found water ice there. Knowing the ices usually exist at the outer parts of the [[Protoplanetary disk|proto-planetary nebulae]], Hersant ''et al.''<ref>{{cite journal | bibcode = 2004P&SS...52..623H | doi=10.1016/j.pss.2003.12.011 | title = Enrichment in volatiles in the giant planets of the Solar System | year = 2004 | last1 = Hersant | first1 = F | journal = Planetary and Space Science | volume = 52 | issue = 7 | pages = 623–641 }}</ref> proposed an interpretation of the [[Volatility (physics)|volatile]] enrichment, observed in the four [[Gas giant|giant planets]] of the [[Solar System]], with respect to the Solar [[Abundance of the chemical elements|abundances]]. They assumed the [[Volatility (physics)|volatiles]] had been trapped in the form of hydrates and incorporated in the [[planetesimal]]s flying in the [[Protoplanet|protoplanets’]] feeding zones.
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| Kieffer ''et al.'' (2006) suggest that the geyser activity in the south polar region of [[Saturn]]'s moon [[Enceladus (moon)|Enceladus]] originates from clathrate hydrates, where carbon dioxide, methane, and nitrogen are released when exposed to the vacuum of space by the "[[Tiger Stripes (Enceladus)|Tiger Stripe]]" fractures found in that area.<ref name=Kieffer2006>{{cite journal| first=Susan W.| last= Kieffer| coauthors= Xinli Lu, Craig M. Bethke, John R. Spencer, Stephen Marshak, Alexandra Navrotsky| year=2006| doi=10.1126/science.1133519| title=A Clathrate Reservoir Hypothesis for Enceladus' South Polar Plume| journal=Science| volume=314| issue=5806| pages=1764–1766| pmid=17170301| bibcode=2006Sci...314.1764K}}</ref>
| | ==Test pages == |
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| [[Carbon dioxide clathrate]] is believed to play a major role in different processes on Mars. [[Hydrogen clathrate]] is likely to form in condensation nebulae for gas giants. | | To test the '''MathML''', '''PNG''', and '''source''' rendering modes, please go to one of the following test pages: |
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| == Hydrates on Earth==
| | *[[Inputtypes|Inputtypes (private Wikis only)]] |
| ===Natural gas hydrates===
| | *[[Url2Image|Url2Image (private Wikis only)]] |
| {{main|Methane clathrate}}
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| Naturally on [[Earth]] gas hydrates can be found on the [[seafloor]], in ocean sediments,<ref>{{cite journal |year=1980 |author1=Kvenvolden, K. A. |author2=McMenamin, M. A. |title=Hydrates of Natural Gas: Their Geologic Occurrence |journal=U. S. Geological Survey Circular |volume=825 }}</ref> in deep lake sediments (e.g. [[Lake Baikal]]), as well as in the [[permafrost]] regions. The amount of [[methane]] potentially trapped in natural [[Methane clathrate|methane hydrate]] deposits may be significant (10<sup>15</sup> to 10<sup>17</sup> cubic metres),<ref>http://www.newscientist.com/article/dn16848-ice-that-burns-could-be-a-green-fossil-fuel.html Ice that burns could be a green fossil fuel [[New Scientist]] 26 March 2009 by Michael Marshall</ref> which makes them of major interest as a potential energy resource. Catastrophic release of methane from the decomposition of such deposits may lead to a global climate change, because [[methane|CH]]<sub>4</sub> is more efficient greenhouse gas even than [[carbon dioxide|CO]]<sub>2</sub> (see [[Atmospheric methane]]). The fast decomposition of such deposits is considered a [[geohazard]], due to its potential to trigger [[landslide]]s, [[earthquake]]s and [[tsunami]]s. However, natural gas hydrates do not contain only methane but also other [[hydrocarbon]] gases, as well as [[Hydrogen sulfide|H<sub>2</sub>S]] and [[Carbon dioxide|CO<sub>2</sub>]]. [[Air hydrates]] are frequently observed in polar ice samples.
| | If you find any bugs, please report them at [https://bugzilla.wikimedia.org/enter_bug.cgi?product=MediaWiki%20extensions&component=Math&version=master&short_desc=Math-preview%20rendering%20problem Bugzilla], or write an email to math_bugs (at) ckurs (dot) de . |
| [[Pingo]]s are common structures in permafrost regions.<ref>{{cite journal | last = Ussler, W.; Paull, C. K.; Lorenson, T.; Dallimore, S.; Medioli, B.; Blasco, S.; McLaughlin, F.; Nixon, F. M. | title = Methane Leakage from Pingo-like Features on the Arctic Shelf, Beaufort Sea, NWT, Canada | work = Physics Abstract Service | publisher = SAO/NASA ADS | month = December | year = 2005 | bibcode = 2005AGUFM.C11A1069U | author1 = Ussler, W. | author2 = Paull, C. K. | author3 = Lorenson, T. | author4 = Dallimore, S. | author5 = Medioli, B. | author6 = Blasco, S. | author7 = McLaughlin, F. | author8 = Nixon, F. M. | volume = 11 | pages = 1069 | journal = American Geophysical Union | last2 = Paull | last3 = Lorenson | last4 = Dallimore | last5 = Medioli | last6 = Blasco | last7 = McLaughlin | last8 = Nixon }}</ref> Similar structures are found in deep water related to methane leakages.
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| It is important to notice that gas hydrates can even be formed in the absence of a liquid phase. Under that situation, water is dissolved in gas or in liquid hydrocarbon phase (<ref>YOUSSEF, Z.; BARREAU, A., MOUGIN, P., JOSE, J.; MOKBEL, I. Ind. Eng. Chem. Res. 2009, 48, 4045-4050</ref>).
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| ===Gas hydrates in pipelines===
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| Thermodynamic conditions favouring hydrate formation are often found in [[Pipeline transport|pipelines]]. This is highly undesirable because the clathrate crystals might agglomerate and plug the flowline<ref>{{cite journal | doi = 10.1021/ef800189k | title = Investigation of Interactions between Gas Hydrates and Several Other Flow Assurance Elements | year = 2008 | last1 = Gao | first1 = Shuqiang | journal = Energy & Fuels | volume = 22 | issue = 5 | pages = 3150–3153 }}</ref> and cause [[flow assurance]] failure and damage valves and instrumentation. The results can range from flow reduction to equipment damage.
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| ====Hydrate formation, prevention and mitigation philosophy====
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| Hydrates have a strong tendency to [[agglomerate]] and to adhere to the pipe wall and thereby plug the pipeline. Once formed, they can be decomposed by increasing the temperature and/or decreasing the pressure. Even under these conditions, the clathrate dissociation is a slow process.
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| Therefore, preventing hydrate formation appears to be the key to the problem. A hydrate prevention philosophy could typically be based on three levels of security, listed in order of priority:
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| # Avoid operational conditions that might cause formation of hydrates by depressing the hydrate formation temperature using [[glycol dehydration]];
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| # Temporarily change [[operating conditions]] in order to avoid hydrate formation;
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| # Prevent formation of hydrates by addition of chemicals that (a) shift the hydrate equilibrium conditions towards lower temperatures and higher pressures or (b) increase hydrate formation time ([[Reaction inhibitor|inhibitor]]s)
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| The actual philosophy would depend on operational circumstances such as pressure, temperature, type of flow (gas, liquid, presences of water etc.)
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| ====Hydrate inhibitors====
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| When operating within a set of parameters where hydrates could be formed, there are still ways to avoid their formation. Altering the gas composition by adding chemicals can lower the hydrate formation temperature and/or delay their formation. Two options generally exist:
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| * Thermodynamic inhibitors
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| * Kinetic inhibitors/anti-agglomerants | |
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| The most common thermodynamic inhibitors are [[methanol]], [[ethylene glycol|monoethylene glycol]] (MEG), and [[diethylene glycol]] (DEG), commonly referred to as [[glycol]]. All may be recovered and recirculated, but the economics of methanol recovery is not favourable in most cases. MEG is preferred over DEG for applications where the temperature is expected to be −10 °C or lower due to high viscosity at low temperatures. [[Triethylene glycol]] (TEG) has too low vapour pressure to be suited as an inhibitor injected into a gas stream. More methanol is lost in the gas phase when compared to MEG or DEG.
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| The use of [[kinetic inhibitor]]s and anti-agglomerants in actual field operations is a new and evolving technology. It requires extensive tests and optimisation to the actual system. While kinetic inhibitors work by slowing down the kinetics of the nucleation, anti-agglomerants do not stop the nucleation, they rather stop the agglomeration (sticking together) of gas hydrate crystals. These two kinds of inhibitors are also known as [[LDHI|Low-Dosage-Hydrate-Inhibitors]] because they require much smaller concentrations than the conventional thermodynamic inhibitors. Kinetic inhibitors (which do not require water and hydrocarbon mixture to be effective) are usually polymers or copolymers and anti-agglomerants (requires water and hydrocarbon mixture) are polymers or [[zwitterionic]] (usually ammonium and COOH) surfactants being both attracted to hydrates and hydrocarbons.
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| ==See also==
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| * [[Clathrate]]
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| * [[Star#Formation and evolution|Star Formation and evolution]]
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| * [[Clathrate gun hypothesis]]
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| ==References== | |
| {{Reflist|2}}
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| ==Further reading==
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| * Shuqiang Gao, Waylon House, and Walter Chapman, “NMR/MRI Study of Clathrate Hydrate Mechanisms”, J. Phys. Chem. B, 109(41), 19090-19093, 2005.
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| * http://gashydrate.fileave.com/NMR-MRI%20study%20of%20clathrate%20hydrate%20mechanisms.pdf
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| * Mohamed Iqbal Pallipurath, "DISSOCIATION OF HYDRATED MARINE SEDIMENT", Oil and Gas Business Journal, 2006 http://www.ogbus.ru/eng/authors/Iqbal/Iqbal_1.pdf
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| * N Sultan, P Cochonat, JP Foucher, J Mienert, Effect of gas hydrates melting on seafloor slope instability - ►ifremer.fr [PDF], - Marine Geology, 2004 - Elsevier http://linkinghub.elsevier.com/retrieve/pii/S0025322704002798
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| ==External links==
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| {{Commons category|Gas hydrates}}
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| * [http://www.ifm-geomar.de/index.php?id=1201&L=1 Gas hydrates], from [http://www.ifm-geomar.de/index.php?id=1&L=1 Leibniz Institute of Marine Sciences], Kiel (IFM-GEOMAR)
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| * [http://www.ifm-geomar.de/index.php?id=3563&L=1 The SUGAR Project (Submarine Gas Hydrate Reservoirs)], from [http://www.ifm-geomar.de/index.php?id=1&L=1 Leibniz Institute of Marine Sciences], Kiel (IFM-GEOMAR)
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| * [http://www.psl-systemtechnik.de/gas_hydrate_autoclave.html?&L=1 Gas hydrates in video] and [http://www.psl-systemtechnik.de/gas_hydrate_autoclave_knowledge.html?&L=1 - Background knowledge about gas hydrates, their prevention and removal] (by manufacturer of hydrate autoclaves)
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| {{DEFAULTSORT:Clathrate Hydrate}}
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| [[Category:Clathrate hydrates| ]]
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| [[Category:Ice]]
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| [[ar:هيدرات الغاز]]
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| [[be:Газавыя гідраты]]
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| [[ca:Hidrat de gas]]
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| [[de:Gashydrat]]
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| [[es:Hidrato de gas]]
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| [[ko:가스 하이드레이트]]
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| [[it:Clatrato idrato]]
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| [[nl:Gashydraat]]
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| [[ja:包接水和物]]
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| [[pt:Hidrato de clatrato]]
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| [[ru:Газовые гидраты]]
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| [[th:มีเทนคลาเทรต]]
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| [[tr:Klatrat hidrat]]
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