Dimethyl ether ( DME; also known as methoxymethane) is the organic compound with the formula CH3OCH3,
(sometimes ambiguously simplified to C2H6O as it is an isomer of ethanol). The simplest ether, it is a colorless gas that is a useful precursor to other organic compounds and an aerosol propellant that is currently being demonstrated for use in a variety of fuel applications.
Dimethyl ether was first synthesised by Jean-Baptiste Dumas and Eugene Péligot in 1835 by distillation of methanol and sulfuric acid.[Ann. chim. phys., 1835, 2 58, p. 19 ]
Production
Approximately 50,000 tons were produced in 1985 in Western Europe by dehydration of
methanol:
[Manfred Müller, Ute Hübsch, "Dimethyl Ether" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. ]
The required methanol is obtained from synthesis gas (
syngas).
Other possible improvements call for a dual catalyst system that permits both methanol synthesis and dehydration in the same process unit, with no methanol isolation and purification.
[P.S. Sai Prasad et al., Fuel Processing Technology, 2008, 89, 1281.]
Both the one-step and two-step processes above are commercially available. The two-step process is relatively simple and start-up costs are relatively low. A one-step liquid-phase process is in development.
From biomass
Dimethyl ether is a synthetic second generation biofuel (BioDME), which can be produced from lignocellulosic biomass.
The Volvo Group is the coordinator for the European Community Seventh Framework Programme project BioDME[ Chemrec press release September 9, 2010 ]
Applications
The largest use of dimethyl ether is as the feedstock for the production of the methylating agent, dimethyl sulfate, which entails its reaction with sulfur trioxide:
Dimethyl ether can also be converted into acetic acid using carbonylation technology related to the Monsanto acetic acid process:[
]
Laboratory reagent and solvent
Dimethyl ether is a low-temperature solvent and extraction agent, applicable to specialised laboratory procedures. Its usefulness is limited by its low boiling point (), but the same property facilitates its removal from reaction mixtures. Dimethyl ether is the precursor to the useful alkylating agent, trimethyloxonium tetrafluoroborate.
Niche applications
A mixture of dimethyl ether and propane is used in some over-the-counter "freeze spray" products to treat by cryosurgery.
Dimethyl ether is also a component of certain high temperature MAPP gas blowtorch gas blends, supplanting the use of methyl acetylene and propadiene mixtures.
Dimethyl ether is also used as a propellant in aerosol products. Such products include hair spray, bug spray and some aerosol glue products.
Research
Fuel
A potentially major use of dimethyl ether is as substitute for propane in LPG used as fuel in household and industry.
It is also a promising fuel in diesel engines,[ nycomb.se, Nycomb Chemicals company ] and gas turbines. For diesel engines, an advantage is the high cetane number of 55, compared to that of diesel fuel from petroleum, which is 40–53.[ topsoe.com] Only moderate modifications are needed to convert a diesel engine to burn dimethyl ether. The simplicity of this short carbon chain compound leads to very low emissions of particulate matter during combustion. For these reasons as well as being sulfur-free, dimethyl ether meets even the most stringent emission regulations in Europe (EURO5), U.S. (U.S. 2010), and Japan (2009 Japan).[, Conference on the Development and Promotion of Environmentally Friendly Heavy Duty Vehicles such as DME Trucks, Washington DC, March 17, 2006]
At the European Shell Eco Marathon, an unofficial World Championship for mileage, a vehicle running on 100 % dimethyl ether drove 589 km/L (0.170 L per 100 km), fuel equivalent to gasoline with a 50 cm3 displacement 2-stroke engine. As well as winning they beat the old standing record of 306 km/L (0.327 L per 100 km), set by the same team in 2007.
To study the dimethyl ether for the combustion process a chemical kinetic mechanism
Refrigerant
Dimethyl ether is a refrigerant with ASHRAE refrigerant designation R-E170.[ A history of the frozen meat trade, page 26-28]
Safety
Unlike other alkyl ethers, dimethyl ether resists autoxidation.[ A comparative study on the autoxidation of dimethyl ether (DME) comparison with diethyl ether (DEE) and diisopropyl ether (DIPE), Michie Naito, Claire Radcliffe, Yuji Wada, Takashi Hoshino, Xiongmin Liu, Mitsuru Arai, Masamitsu Tamura. Journal of Loss Prevention in the Process Industries, Volume 18, Issues 4–6, July–November 2005, Pages 469–473 DOI] Dimethyl ether is also relatively non-toxic, although it is highly flammable. On July 28, 1948, a BASF factory in Ludwigshafen suffered an explosion after 30 tonnes of dimethyl ether leaked from a tank and ignited in the air. 200 people died, and a third of the industrial plant was destroyed.[ Welt im Film 167/1948 . filmothek.bundesarchiv.de]
Data sheet
Routes to produce dimethyl ether
Vapor pressure
+ Experimental vapor pressures of dimethyl ether |
|
| 54.61 |
| 68.49 |
| 85.57 |
| 105.59 |
| 129.42 |
| 157.53 |
| 190.44 |
| 228.48 |
| 272.17 |
| 321.87 |
| 378.66 |
| 443.57 |
| 515.53 |
| 596.21 |
| 687.37 |
| 726.26 |
| 787.07 |
| 897.59 |
| 968.55 |
| 1018.91 |
| 1152.35 |
| 1298.23 |
| 1457.5 |
| 1457.76 |
| 1631.01 |
| 1818.8 |
| 2022.45 |
| 2242.74 |
| 2243.07 |
| 2479.92 |
| 2735.67 |
| 3010.81 |
| 3305.67 |
| 3622.6 |
| 3962.25 |
| 4331.48 |
| 4725.02 |
| 5146.82 |
| 5355.8 |
See also
External links
