词条 | Gas to liquids |
释义 |
The motivation for GTL is to produce liquid fuels, which are more readily transported than methane. Methane must be cooled below its critical temperature of -82.3 °C in order to be liquified under pressure. Because of the associated cryogenic apparatus, LNG tankers are expensive, not to mention potentially dangerous. Methanol is a conveniently handled combustible liquid, but its energy density is half of that of gasoline.[3] Fischer–Tropsch process{{Main|Fischer–Tropsch process}}The Fischer–Tropsch process starts with partial oxidation of methane (natural gas) to carbon dioxide, carbon monoxide, hydrogen gas and water. The ratio of carbon monoxide to hydrogen is adjusted using the water gas shift reaction, while the excess carbon dioxide is removed. Removing the water yields synthesis gas (syngas). Syngas is allowed to react over an iron or cobalt catalyst to produce liquid hydrocarbons, including alcohols. Methane to methanol processMethanol is made from methane (natural gas) in a series of three reactions:
CH4 + H2O → CO + 3 H2 {{pad|2em}} ΔrH = +206 kJ mol−1
CO + H2O → CO2 + H2 {{pad|2.5em}} ΔrH = -41 kJ mol−1
2 H2 + CO → CH3OH {{pad|3.5em}} ΔrH = -92 kJ mol−1 The methanol thus formed may be converted to gasoline by the Mobil process and methanol-to-olefins. Methanol to gasoline (MTG) and methanol to olefinsIn the early 1970s, Mobil developed an alternative procedure in which natural gas is converted to syngas, and then methanol. The methanol reacts in the presence of a zeolite catalyst to form alkanes. In terms of mechanism, methanol is partially dehydrated to give dimethyl ether: 2 CH3OH → CH3OCH3 + H2O The mixture of dimethyl ether and methanol is then further dehydrated over a zeolite catalyst such as ZSM-5, which in practice is polymerized and hydrogenated to give a gasoline with hydrocarbons of five or more carbon atoms making up 80% of the fuel by weight. The Mobile MTG process is no longer practiced. A more modern implementation of MTG is the Topsøe integrated gasoline synthesis (TIGS).[4] Methanol can can be converted to olefins using zeolite and SAPO-based heterogeneous catalysts. Depending on the catalyst pore size, this process can afford either C2 or C3 products, which are important monomers.[5][6] Syngas to gasoline plus process (STG+){{Main|Syngas to gasoline plus}}A third gas-to-liquids process builds on the MTG technology by converting natural gas-derived syngas into drop-in gasoline and jet fuel via a thermochemical single-loop process.[7] The STG+ process follows four principal steps in one continuous process loop. This process consists of four fixed bed reactors in series in which a syngas is converted to synthetic fuels. The steps for producing high-octane synthetic gasoline are as follows:[8]
Biological gas-to-liquids (Bio-GTL)With methane as the predominant target for GTL, much attention has focused on the three enzymes that process methane. These enzymes support the existence of methanotrophs, microorganisms that metabolize methane as their only source of carbon and energy. Aerobic methanotrophs harbor enzymes that oxygenate of methane to methanol. The relevant enzymes are methane monooxygenases, which are found both in soluble and particulate (i.e. membrane-bound) varieties. They catalyze the oxygenation according to the following stoichiometry: CH4 + O2 + NADPH + H+ → CH3OH + H2O + NAD+ Anaerobic methanotrophs rely on the bioconversion of methane using the enzymes called methyl-coenzyme M reductases. These organisms effect reverse methanogenesis. Strenuous efforts have been made to elucidate the mechanisms of these methane-converting enzymes, which would enable their catalysis to be replicated in vitro.[9] Biodiesel can be made from {{CO2}} using the microbes Moorella thermoacetica and Yarrowia lipolytica. This process is known as biological gas-to-liquids.[10]Commercial usesUsing gas-to-liquids processes, refineries can convert some of their gaseous waste products (flare gas) into valuable fuel oils, which can be sold as is or blended only with diesel fuel. The World Bank estimates that over {{convert|150|e9m3}} of natural gas are flared or vented annually, an amount worth approximately $30.6 billion, equivalent to 25% of the United States' gas consumption or 30% of the European Union's annual gas consumption,[11] a resource that could be useful using GTL. Gas-to-liquids processes may also be used for the economic extraction of gas deposits in locations where it is not economical to build a pipeline. This process will be increasingly significant as crude oil resources are depleted. Royal Dutch Shell produces a diesel from natural gas in a factory in Bintulu, Malaysia. Another Shell GTL facility is the Pearl GTL plant in Qatar, the world's largest GTL facility.[12][13] SASOL has recently built the Oryx GTL facility in Ras Laffan Industrial City, Qatar and together with Uzbekneftegaz and Petronas builds the Uzbekistan GTL plant.[14][15][16] Chevron Corporation, in a joint venture with the Nigerian National Petroleum Corporation is commissioning the Escravos GTL in Nigeria, which uses Sasol technology. Aspirational and emerging venturesNew generation of GTL technology is being pursued for the conversion of unconventional, remote and problem gas into valuable liquid fuels.[17][18] GTL plants based on innovative Fischer–Tropsch catalysts have been built by INFRA Technology. Other mainly U.S. companies include Velocys, ENVIA Energy, Waste Management, NRG Energy, Ventech, Velocys, ThyssenKrupp Industrial Solutions, Liberty GTL, Petrobras,[19] and Greenway Innovative Energy,[20] Primus Green Energy,[21] and Compact GTL.[22] and Petronas.[23] Several of these processes have proven themselves with demonstration flights using their jet fuels.[24] [25]Another proposed solution to stranded gas involves use of novel FPSO for offshore conversion of gas to liquids such as methanol, diesel, petrol, synthetic crude, and naphtha.[26] See also
References1. ^{{cite journal|last1=Höök|first1=Mikael|last2=Fantazzini|first2=Dean|last3=Angelantoni|first3=André|last4=Snowden|first4=Simon|title=Hydrocarbon liquefaction: viability as a peak oil mitigation strategy|journal=Philosophical Transactions of the Royal Society A|date=2013|volume=372|issue=2006|doi=10.1098/rsta.2012.0319|PMID = 24298075|url = http://uu.diva-portal.org/smash/record.jsf?pid=diva2:670680|accessdate = 2009-06-03|bibcode=2013RSPTA.37220319H}} 2. ^{{Cite book |title=Ullmann's Encyclopedia of Industrial Chemistry |last=Kaneko |first=Takao |last2=Derbyshire |first2=Frank |last3=Makino |first3=Eiichiro |last4=Gray |first4=David |last5=Tamura |first5=Masaaki |date=2001 |publisher=Wiley-VCH |isbn=9783527306732 |location=Weinheim |chapter=Coal Liquefaction |doi=10.1002/14356007.a07_197}} 3. ^https://www.afdc.energy.gov/fuels/fuel_properties.php 4. ^{{cite journal|authors=Olsbye, U.; Svelle, S.; Bjorgen, M.; Beato, P.; Janssens, T. V. W.; Joensen, F.; Bordiga, S.; Lillerud, K. P.|title=Conversion of Methanol to Hydrocarbons: How Zeolite Cavity and Pore Size Controls Product Selectivity|journal=Angew. Chem. Int. Ed.|year=2012|volume=51|pages=5810–5831|doi=10.1002/anie.201103657}} 5. ^{{cite journal|authors=Tian, P.; Wei, Y.; Ye, M.; Liu, Z.|title=Methanol to Olefins (MTO): From Fundamentals to Commercialization|journal=ACS Catal.|year=2015|volume=5|pages=1922–1938|doi=10.1021/acscatal.5b00007}} 6. ^{{cite journal|title=New Trends in Olefin Production|authors=Ismaël Amghizar, Laurien A. Vandewalle, Kevin M. Van Geem, Guy B. Marin|doi=10.1016/J.ENG.2017.02.006|journal=Engineering|year=2017|volume=3|pages=171–178}} 7. ^LaMonica, Martin. Natural Gas Tapped as Bridge to Biofuels MIT Technology Review, 27 June 2012. Retrieved: 7 March 2013. 8. ^Introduction to Primus' STG+ Technology Primus Green Energy, undated. Retrieved: 5 March 2013. 9. ^{{cite journal|authors=Lawton, T. J.; Rosenzweig, A. C.|title=Biocatalysts for methane conversion: big progress on breaking a small substrate|journal=Curr. Opin. Chem. Biol.|year=2016|volume=35|pages=142–149|doi=10.1016/j.cbpa.2016.10.001}} 10. ^Microbes paired for biological gas-to-liquids (Bio-GTL) process 11. ^World Bank, GGFR Partners Unlock Value of Wasted Gas", World Bank 14 December 2009. Retrieved 17 March 2010. 12. ^{{cite web| url = http://www.chemicals-technology.com/projects/pearl-gtl/| title =Pearl Gas-to-Liquids Plant, Ras Laffan, Qatar | accessdate = 2009-06-22}} 13. ^{{cite web| url= https://www.wsj.com/articles/SB10001424052702304072004577323770856080102| title =Shell Weighs Natural Gas-to-Diesel Processing Facility for Louisiana | accessdate = 2012-05-05}} 14. ^{{cite news | url = http://www.upstreamonline.com/live/article175457.ece | title = Petronas signs Uzbek GTL pact | newspaper = Upstream Online | publisher = NHST Media Group | date = 2009-04-08 | accessdate = 2009-07-18 | id = {{subscription required}}}} 15. ^{{cite news | url = http://uk.reuters.com/article/idUKSP2975220080514?sp=true | title = Malaysia's Petronas in Uzbekistan oil-production deal | agency = Reuters | date = 2009-05-14 | accessdate = 2009-07-18}} 16. ^{{cite journal | url = http://www.ogj.com/index/article-display/8316069679/articles/oil-gas-journal/processing-2/gas-processing/gtl/2010/03/contract-let_for_gtl.html | title = Contract let for GTL plant in Uzbekistan | publisher = PennWell Corporation | journal = Oil & Gas Journal | date = 2010-03-08 | accessdate = 2010-03-14 |id= {{subscription required}}}} 17. ^http://gasprocessingnews.com/features/201706/smaller-scale-and-modular-technologies-drive-gtl-industry-forward.aspx 18. ^{{cite web|last=Popov|first=Dmitry|title=Unlocking the value of stranded and remote offshore gas assets|url=http://dm.epmag.com/i/754860-dec-2016}} 19. ^http://compactgtl.com/wp-content/documents/120120_Upstream.pdf 20. ^https://www.globenewswire.com/news-release/2018/03/07/1417633/0/en/Greenway-Technologies-Inc-Marks-Milestone-Completes-First-Commercial-G-Reformer.html 21. ^https://www.primusge.com/?press-release=primus-green-energy-demonstration-plant-operating-results-confirm-compelling-performance-and-economics-according-to-independent-engineers-report. 22. ^https://www.technologyreview.com/s/418020/turning-gas-flares-into-fuel/ 23. ^https://uk.reuters.com/article/petronas-uzbekistan/update-2-malaysias-petronas-in-uzbekistan-oil-production-deal-idUKSP2975220080514?sp=true 24. ^https://www.rigzone.com/news/oil_gas/a/149274/Qatar_Airways_Makes_GTL_History/?oc=dst 25. ^https://www.reuters.com/article/environment-airbus-fuel-dc/a380-makes-test-flight-on-alternative-fuel-idUSL0120071420080201?rpc=64 26. ^{{cite web|url=http://www.bpp-tech.com/index.php?option=com_content&view=article&id=60&Itemid=59 |title=Innovative Engineering in Energy Technologies |publisher=Bpp-Tech |date= |accessdate=2014-04-12}} 3 : Natural gas technology|Synthetic fuel technologies|Industrial gases |
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