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Dimethyl ether
Dimethyl ether
Dimethyl ether
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Not to be confused with dimethoxyethane.
Dimethyl ether
Skeletal formula of dimethyl ether with all implicit hydrogens shown
Skeletal formula of dimethyl ether with all implicit hydrogens shown
Ball and stick model of dimethyl ether
Ball and stick model of dimethyl ether
Names
Preferred IUPAC name
Methoxymethane[1]
Other names
Dimethyl ether[1]
R-E170
Demeon
Dimethyl oxide
Dymel A
Methyl ether
Methyl oxide
Mether
Wood ether
Identifiers
3D model (JSmol)
Abbreviations DME
1730743
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.696 Edit this at Wikidata
EC Number
  • 204-065-8
KEGG
MeSH Dimethyl+ether
RTECS number
  • PM4780000
UNII
UN number 1033
  • InChI=1S/C2H6O/c1-3-2/h1-2H3 checkY
    Key: LCGLNKUTAGEVQW-UHFFFAOYSA-N checkY
  • InChI=1/C2H6O/c1-3-2/h1-2H3
    Key: LCGLNKUTAGEVQW-UHFFFAOYAU
  • COC
Properties
C2H6O
Molar mass 46.069 g·mol−1
Appearance Colorless gas
Odor Ethereal[2]
Density 2.1146 kg m−3 (gas, 0 °C, 1013 mbar)[2]
0.735 g/mL (liquid, −25 °C)[2]
Melting point −141 °C; −222 °F; 132 K
Boiling point −24 °C; −11 °F; 249 K
71 g/L (at 20 °C (68 °F))
log P 0.022
Vapor pressure 592.8 kPa[3]
−26.3×10−6 cm3 mol−1
1.30 D
Thermochemistry
65.57 J K−1 mol−1
−184.1 kJ mol−1
−1460.4 kJ mol−1
Hazards
GHS labelling:[4]
GHS02: Flammable
Danger
H220
P210, P377, P381, P403
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
2
4
1
Flash point −41 °C (−42 °F; 232 K)
350 °C (662 °F; 623 K)
Explosive limits 27 %
Safety data sheet (SDS) ≥99% Sigma-Aldrich
Related compounds
Related ethers
 Diethyl ether

Polyethylene glycol

Related compounds
 Ethanol

Methanol

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

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.[5]

Production

[edit]

Approximately 50,000 tons were produced in 1985 in Western Europe by dehydration of methanol:[6]

2 CH3OH → (CH3)2O + H2O

The required methanol is obtained from synthesis gas (syngas).[7] 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.[7][8] 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.[7][9]

From biomass

[edit]

Dimethyl ether is a synthetic second generation biofuel (BioDME), which can be produced from lignocellulosic biomass.[10] The EU is considering BioDME in its potential biofuel mix in 2030;[11] It can also be made from biogas or methane from animal, food, and agricultural waste,[12][13] or even from shale gas or natural gas.[14]

The Volvo Group is the coordinator for the European Community Seventh Framework Programme project BioDME[15][16] where Chemrec's BioDME pilot plant is based on black liquor gasification in Piteå, Sweden.[17]

Applications

[edit]

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:

CH3OCH3 + SO3 → (CH3)2SO4

Dimethyl ether can also be converted into acetic acid using carbonylation technology related to the Monsanto acetic acid process:[6]

(CH3)2O + 2 CO + H2O → 2 CH3CO2H

Laboratory reagent and solvent

[edit]

Dimethyl ether is a low-temperature solvent and extraction agent, applicable to specialised laboratory procedures. Its usefulness is limited by its low boiling point (−23 °C (−9 °F)), but the same property facilitates its removal from reaction mixtures. Dimethyl ether is the precursor to the useful alkylating agent, trimethyloxonium tetrafluoroborate.[18]

Niche applications

[edit]

A mixture of dimethyl ether and propane is used in some over-the-counter "freeze spray" products to treat warts by freezing them.[19][20] In this role, it has supplanted halocarbon compounds (Freon).

Dimethyl ether is also a component of certain high temperature "Map-Pro" blowtorch gas blends, supplanting the use of methyl acetylene and propadiene mixtures.[21]

Dimethyl ether is also used as a propellant in aerosol products. Such products include hair spray, bug spray and some aerosol glue products.

Research

[edit]

Fuel

[edit]
Installation of BioDME synthesis towers at Chemrec's pilot facility

A potentially major use of dimethyl ether is as substitute for propane in LPG used as fuel in household and industry.[22] Dimethyl ether can also be used as a blendstock in propane autogas.[23]

It is also a promising fuel in diesel engines,[24] 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.[25] 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).[26]

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.[27]

To study the dimethyl ether for the combustion process a chemical kinetic mechanism[28] is required which can be used for Computational fluid dynamics calculation.

Refrigerant

[edit]

Dimethyl ether is a refrigerant with ASHRAE refrigerant designation R-E170.[29] It is also used in refrigerant blends with e.g. ammonia, carbon dioxide, butane and propene. Dimethyl ether was the first refrigerant. In 1876, the French engineer Charles Tellier bought the ex-Elder-Dempster a 690 tons cargo ship Eboe and fitted a methyl-ether refrigerating plant of his design. The ship was renamed Le Frigorifique and successfully imported a cargo of refrigerated meat from Argentina. However the machinery could be improved and in 1877 another refrigerated ship called Paraguay with a refrigerating plant improved by Ferdinand Carré was put into service on the South American run.[30]

Safety

[edit]

Unlike other alkyl ethers, dimethyl ether resists autoxidation.[31] 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.[32]

Data sheet

[edit]

Routes to produce dimethyl ether

[edit]

Vapor pressure

[edit]
Experimental vapor pressures of dimethyl ether[33]
Temperature (K) Pressure (kPa)
233.128 54.61
238.126 68.49
243.157 85.57
248.152 105.59
253.152 129.42
258.16  157.53
263.16  190.44
268.161 228.48
273.153 272.17
278.145 321.87
283.16  378.66
288.174 443.57
293.161 515.53
298.172 596.21
303.16  687.37
305.16  726.26
308.158 787.07
313.156 897.59
316.154 968.55
318.158 1018.91
323.148 1152.35
328.149 1298.23
333.157 1457.5 
333.159 1457.76
338.154 1631.01
343.147 1818.8 
348.147 2022.45
353.146 2242.74
353.158 2243.07
358.145 2479.92
363.148 2735.67
368.158 3010.81
373.154 3305.67
378.15  3622.6 
383.143 3962.25
388.155 4331.48
393.158 4725.02
398.157 5146.82
400.378 5355.8 

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Dimethyl ether

View on Grokipedia
from Grokipedia
Dimethyl ether (DME), chemically denoted as CH₃OCH₃, is the simplest , consisting of two methyl groups linked by an oxygen atom, and exists as a colorless, low-boiling gas at . With a molecular weight of 46.07 g/mol and a of -24.8 °C, it can be readily liquefied under moderate for storage and transport, exhibiting properties akin to (LPG). Flammable yet low in toxicity, DME features a faint ethereal odor and high , rendering it suitable for applications requiring rapid . The compound's primary industrial use centers on its role as an aerosol propellant in products like hairsprays, foams, and insecticides, prized for its non-ozone-depleting nature and with and solvents. Additionally, it serves as a (under designation R-E170), extracting agent, and chemical intermediate for synthesizing compounds such as and acetic acid. Its production, chiefly via catalytic dehydration of sourced from or , positions DME as a versatile intermediate in chemical manufacturing. Emerging applications highlight DME's potential as a diesel substitute in compression-ignition engines, where its high (around 55) and oxygen content enable low-NOx and soot-free combustion, potentially reducing particulate emissions compared to conventional fuels. Research underscores its viability for blending with diesel or use in dedicated engines, supported by infrastructure similarities to LPG, though challenges include lower requiring larger storage volumes. Safety considerations emphasize its extreme flammability, with an NFPA health rating of 2 due to asphyxiation risks in confined spaces, necessitating careful handling akin to other compressed gases.

Properties

Physical Properties

Dimethyl ether has the molecular formula C₂H₆O (or CH₃OCH₃) and a of 46.068 g/mol. It exists as a colorless gas under conditions, exhibiting a faint ethereal . The compound's is -141.5 °C, and its normal is -24.8 °C, allowing it to liquefy readily under moderate at ambient temperatures. Key physical parameters include a liquid density of approximately 0.66 g/cm³ at its and a of 5.2 bar at 20 °C, contributing to its high volatility. The relative to air is 1.6, indicating it is heavier than air and may accumulate in low-lying areas. in is limited at 71 g/L (or 7.1 g/100 mL) at 20 °C, though it mixes well with organic solvents. Thermodynamic properties relevant to phase behavior include a critical temperature of 126.9 °C and a critical pressure of 53.7 bar. These values define the conditions beyond which dimethyl ether cannot be liquefied by pressure alone, influencing its handling in pressurized systems.
PropertyValueConditions
46.068 g/mol-
Melting point-141.5 °C1 atm
Boiling point-24.8 °C1 atm
Liquid density0.66 g/cm³At boiling point
Vapor pressure5.2 bar20 °C
Critical temperature126.9 °C-
Critical pressure53.7 bar-
Water solubility71 g/L20 °C

Chemical Properties

Dimethyl ether (DME), with molecular formula CH₃OCH₃, possesses a symmetrical structure featuring a central oxygen atom bonded to two methyl groups, forming a C-O-C backbone with bond angles around 111° due to sp³ hybridization on oxygen. This configuration results in low molecular polarity and dipole moment of 1.3 D, conferring general chemical stability under neutral or basic conditions, as the ether linkage resists nucleophilic attack absent . DME demonstrates inertness toward most bases, oxidants, and reductants at ambient temperatures, owing to the absence of easily abstractable hydrogens or labile functional groups beyond the ether oxygen. However, in acidic environments, the oxygen can be protonated, facilitating cleavage reactions such as to two molecules of , a process thermodynamically favored above 350°C with acid catalysts like γ-Al₂O₃ or zeolites, though equilibrium-limited without removal of products. Strong acids like HI or HBr cleave the C-O bond via SN2 mechanisms on the methyl groups, yielding methyl halides and , highlighting vulnerability to electrophilic conditions. Combustion of DME proceeds via radical chain mechanisms, with a of 3.4 vol% and upper limit of 18.6 vol% in air, enabling wide ignition ranges. The is 350°C, and the lower heating value reaches 28.8 MJ/kg, reflecting efficient oxidation to CO₂ and H₂O due to the oxygenated structure reducing formation compared to hydrocarbons. These traits underscore DME's energetic reactivity while maintaining stability absent ignition sources or .

Production

Indirect Synthesis via Methanol

The indirect synthesis of dimethyl ether (DME) proceeds via a two-step process where , derived from , undergoes . Methanol is first produced from synthesis gas (CO and H₂) using established industrial methods, followed by its conversion to DME. This approach has historically dominated DME production since the mid-20th century, initially as a of high-pressure methanol synthesis and later optimized with low-pressure processes. The step follows the reaction 2 CH₃OH → CH₃OCH₃ + H₂O, conducted in the gas phase over solid acid catalysts such as γ-alumina or zeolites. Typical operating conditions include temperatures of 200–400 °C and pressures of 1–20 bar, with the reaction being exothermic and thermodynamically favored at lower temperatures but kinetically requiring elevated for practical rates. Catalysts like γ-alumina exhibit high activity due to their acidic sites, enabling adsorption and subsequent , while zeolites such as provide shape selectivity to minimize side reactions. Conversion yields can reach up to 99% with per-pass selectivities exceeding 95% under optimized conditions, facilitated by fixed-bed reactors and removal to shift equilibrium. This method offers advantages including high selectivity, compatibility with existing methanol production facilities, and reduced need for novel catalyst development compared to direct syngas routes. However, it demands high-purity feedstock to prevent byproducts like higher ethers or hydrocarbons, and the two-step nature incurs additional energy for purification and , with overall process energy inputs estimated at 30–35 MJ per kg of DME. Economic feasibility hinges on pricing and syngas availability, as integrated plants can achieve cost efficiencies through heat recovery and shared infrastructure.

Direct Synthesis from Syngas

Direct synthesis of dimethyl ether (DME) from proceeds via a one-step in which (CO) and (H₂) react over bifunctional hybrid catalysts combining methanol synthesis and dehydration functionalities within a single . These catalysts typically integrate Cu/ZnO/Al₂O₃ for CO hydrogenation to with acidic components such as HZSM-5 or γ-alumina for subsequent methanol dehydration to DME. feedstocks are primarily produced from fossil sources, including through (yielding H₂/CO ratios of approximately 3:1) or (yielding lower ratios around 1:1 to 2:1), enabling large-scale production due to abundant reserves and established infrastructure. The reaction operates at temperatures of 240–280 °C and pressures of 30–70 bar, conditions that balance kinetics for methanol formation and while managing exothermicity. CO conversions reach 50–80% per pass in fixed-bed or reactors, surpassing the 15–25% typical in standalone methanol synthesis due to in-situ DME removal shifting equilibrium. DME selectivity exceeds 95% with optimized hybrid formulations, such as those incorporating heteropolyacids or modified zeolites to enhance sites and suppress byproducts. Yields correspond to approximately 0.5–0.6 kg DME per kg under stoichiometric conditions, reflecting efficient carbon utilization despite side reactions. This integrated approach reduces process steps and capital costs by 20–30% compared to indirect two-stage methanol-to-DME routes, primarily through simplified design and higher per-pass conversion. However, challenges persist, including equilibrium limitations from the water-gas shift reaction (CO + H₂O ⇌ CO₂ + H₂), which generates water that deactivates Cu sites via or blocks acid functions, necessitating advanced formulations or water removal strategies. deactivation remains a key scalability hurdle, with recent bifunctional systems demonstrating improved stability via structured distributions of active phases to mitigate hotspots and maintain selectivity over extended operation.

Production from Alternative Feedstocks

Dimethyl ether production from biomass involves gasification of lignocellulosic feedstocks, such as forestry residues or black liquor, to generate syngas, which is then converted to DME via established catalytic synthesis routes. This approach has been demonstrated in pilot-scale facilities, including Chemrec's plant in Piteå, Sweden, inaugurated in September 2010 at the Smurfit Kappa paper mill, utilizing black liquor gasification to produce approximately 4 tonnes of bio-DME annually. The process achieves biomass-to-DME yields of 6 to 7 tonnes of dry biomass per tonne of DME, with gasification efficiencies exceeding 82% in optimized systems. Despite technical feasibility, bio-DME faces economic disadvantages relative to fossil-based production, with costs estimated at up to four times higher than DME from low-cost natural gas due to elevated feedstock handling, preprocessing for moisture and impurities, and lower overall energy efficiency from dilute biomass energy content. Variable syngas quality from heterogeneous biomass sources necessitates extensive cleaning and conditioning, increasing operational complexity and capital requirements compared to consistent fossil syngas streams from natural gas reforming or coal gasification. Scalability is further constrained by logistical challenges in biomass supply chains and potential land-use competition, yielding lower energy return on investment than fossil alternatives. CO₂ utilization routes for DME production typically proceed via to (CO₂ + 3H₂ → CH₃OH + H₂O) followed by , relying on from renewable-powered . This pathway demands high-purity CO₂ capture and substantial input, with energy penalties from electrolysis efficiencies below 70% rendering the process thermodynamically inefficient without subsidized renewable electricity. Economic analyses indicate costs dominate, comprising over 60% of production expenses, limiting commercial deployment to niche or subsidized applications amid current prices exceeding $3-5 per kg. Pilot and lab-scale efforts persist, but remains hindered by catalyst deactivation under CO₂-rich conditions and the absence of large-scale renewable , contrasting with mature fossil feedstock availability.

Applications

Fuel Applications

Dimethyl ether (DME) serves as a viable substitute in compression ignition (CI) engines due to its high of 55-60, which exceeds that of conventional diesel (typically 40-45), facilitating efficient autoignition. Its oxygen content of approximately 35% by weight promotes cleaner combustion with minimal formation, as the embedded oxygen reduces the need for atmospheric air in oxidation reactions, yielding near-zero particulate matter emissions compared to diesel. However, DME's low necessitates additives and engine modifications, such as hardened seals and injectors compatible with its lower viscosity and of -24°C, to prevent wear in standard diesel hardware. In vehicle applications, DME demonstrates compatibility with up to 90% of components in retrofitted systems, as evidenced by demonstration trials in and since the early 2000s, where it achieved thermal efficiencies comparable to diesel while reducing and particulate matter (PM) emissions through optimized injection timing and . Pilot projects in Chinese cities by reported PM reductions up to 90% and decreases, attributed to DME's smoke-free combustion profile. DME is also blended with (LPG) at ratios up to 20% for household cooking fuels, particularly in , where it enhances flame stability and extends supply amid LPG import dependencies. Countries like , leveraging abundant reserves, are advancing coal-to-DME projects targeted for 2025 to substitute LPG imports, with planned facilities in and aimed at downstream processing of low-rank . These initiatives offer economic advantages in coal-rich regions by converting domestic feedstocks into higher-value fuels, though they require for storage as a under moderate pressure of about 0.5 MPa at ambient temperatures, similar to LPG systems.

Refrigerant and Propellant Uses

Dimethyl ether, designated as refrigerant , exhibits a (GWP) of 1 and zero (ODP), positioning it as a low-impact alternative to hydrofluorocarbons (HFCs) and chlorofluorocarbons (CFCs) in select applications. Its thermodynamic properties, including a of -24.8 °C and favorable characteristics, enable efficient performance in low-temperature systems such as domestic refrigerators and commercial chillers, with studies showing (COP) improvements up to 29.8% over (R290) in vapor compression cycles. However, its classification as a highly flammable (ASHRAE A3) has prompted regulatory restrictions, including phase-outs in regions like the for certain household appliances since the early , favoring less flammable options despite R-E170's environmental merits. As an aerosol propellant, dimethyl ether has been employed since the 1940s in products like hairsprays, deodorants, and technical sprays, valued for its ability to generate fine, uniform mists through a of approximately 5.3 bar at 20 °C. It offers formulation advantages over traditional hydrocarbons such as , including complete with and many organic solvents, which facilitates stable emulsions in aqueous-based products without separation issues. This property, combined with chemical inertness and lower odor, supports its use in personal care and household aerosols, where it comprises an estimated 10-25% of the non-food market volume globally as of 2022. Adoption accelerated post-1970s as a replacement for chlorofluorocarbons under the , though hydrocarbons remain dominant in volume due to cost.

Chemical and Industrial Applications

Dimethyl ether (DME) functions as a low-temperature solvent in laboratory and industrial extractions due to its boiling point of -24.8 °C, enabling selective dissolution and facile recovery by evaporation. It extracts lipids directly from wet microalgae biomass, such as Chlorella sorokiniana, bypassing energy-intensive drying steps and preserving sensitive compounds like polyunsaturated fatty acids. Similarly, liquefied DME recovers terpenoids from pine needle biomass and γ-oryzanol-rich bio-oils from rice bran, outperforming traditional hexane in yield and sustainability by minimizing solvent residues and oxidation. Its solvency, characterized by Hansen solubility parameters (δ_d ≈ 14.2 MPa^{1/2}, δ_p ≈ 2.0 MPa^{1/2}, δ_h ≈ 5.0 MPa^{1/2}), suits non-polar to moderately polar solutes, including polymers in dewatering superabsorbent materials via liquid-phase extraction. As a chemical , DME serves as a methylating agent in , facilitating reactions under mild conditions with catalysts. In catalytic processes, it acts as an intermediate for producing higher-value chemicals, including olefins via the dimethyl ether-to-olefins (DTO) pathway over catalysts like HZSM-5 or mordenite, where forms surface methoxy that initiate C-C coupling to yield and . Yields reach 70-80% for light olefins at 400-500 °C and , though selectivity depends on catalyst dealumination and modification to suppress coke formation. In niche industrial roles, DME extracts aromatics and deasphalts heavy oils in processes, enhancing separation as a green alternative to or in solvent deasphalting units. Its use in subcritical extraction for bioactive compounds from underscores applications in , where it avoids halogenated s and supports downstream purification.

Safety and Toxicology

Health Effects and Toxicity

Dimethyl ether exhibits low acute toxicity, with a 4-hour LC50 of 164,000 ppm in rats and a cardiac threshold exceeding 200,000 ppm in dogs. In humans, exposure to 50,000–75,000 ppm for 12 minutes induces mild intoxication characterized by slight inattention but no severe objective symptoms. The primary health risk at high concentrations arises from its action as a simple asphyxiant, displacing oxygen and causing (CNS) depression, , or when levels exceed 15–30% by volume in air; concentrations of 5–7.5% may produce mild intoxicating effects after brief exposure. Chronic inhalation studies in rats, including 2-year exposures up to 25,000 ppm, demonstrate no carcinogenicity and only minimal effects such as reversible liver weight reductions or slight at the highest doses, with no-observed-adverse-effect concentrations (NOAECs) at or above 10,000 ppm. Dimethyl ether is non-mutagenic in both and assays and shows no genotoxic potential. Although no formal OSHA (PEL) exists, industry and expert recommendations propose an 8-hour time-weighted average (TWA) of 1,000 ppm, below which no chronic adverse effects are observed in animal models or human experience. Dimethyl ether undergoes minimal systemic absorption and metabolism, primarily exhaling unchanged due to low biological reactivity; any partial breakdown yields trace , but without significant toxic metabolite accumulation. In cases of misuse as an , such as intentional high-dose for euphoric effects, symptoms include CNS depression, , and coordination impairment, with rare fatalities reported from overdose leading to asphyxiation or ; however, its toxicity profile is lower than that of hydrocarbon propellants like .

Flammability and Storage Hazards

Dimethyl ether is a highly flammable with a of -41°C and an of 350°C. Its flammability limits in air range from a lower explosive limit of 3.4% to an upper limit of 18.6% by volume, enabling ignition across a broad concentration range and posing risks of vapor cloud explosions from leaks. The assigns it a flammability rating of 4, indicating severe fire hazard when exposed to ignition sources. Storage requires pressurized vessels, as dimethyl ether liquefies at 5-6 bar at ambient temperatures (around 20-25°C), necessitating robust spheres, cylinders, or tubes designed to withstand pressures up to 10 bar or more to prevent rupture from . Leaks from such systems can rapidly form ignitable mixtures due to its vapor density of 1.6 relative to air, leading to heavier-than-air accumulation in low-lying areas. Autoignition risks are mitigated by avoiding high temperatures, though rapid pressure buildup from heating can cause explosions even without ignition. Industrial incidents involving dimethyl ether remain rare, attributed to engineering controls like leak detection and ventilation, though notable events include a 2019 explosion in from an LPG/DME mixture, causing 4 deaths and 10 injuries due to overpressurization and ignition. Another case involved a tank car overfill leading to rupture hazards, underscoring the need for precise fill levels to avoid expansion under . Dimethyl ether's odorless nature heightens undetected leak risks without added odorants or sensors, emphasizing reliance on instrumental monitoring over sensory detection.

Environmental Impact

Combustion Emissions Profile

Dimethyl ether (DME) combustion in compression-ignition engines exhibits a favorable emissions profile compared to conventional diesel fuel, particularly in particulate matter (PM). Engine tests demonstrate PM reductions of up to 90% relative to diesel, attributable to DME's 34.8% oxygen content by mass, which promotes more complete oxidation and eliminates soot precursors through the absence of carbon-carbon bonds and aromatic compounds. This oxygenated structure, combined with a high hydrogen-to-carbon atomic ratio of 3:1, minimizes incomplete combustion products like soot, yielding near-zero PM in many laboratory and prototype evaluations. Nitrogen oxides (NOx) emissions from DME are variable but generally comparable to or lower than diesel under optimized conditions, such as with exhaust gas recirculation (EGR), which DME tolerates at higher rates due to its clean-burning nature and high cetane number (55-60). Carbon monoxide (CO) and hydrocarbons (HC) are typically lower or equivalent, reflecting enhanced combustion efficiency from the fuel's volatility and reactivity. Sulfur oxides (SOx) are absent, as DME contains no sulfur. Tailpipe CO₂ emissions per megajoule of energy are approximately 10-15% lower than diesel on a combustion-only basis, stemming from DME's lower carbon content (52% by mass) relative to its lower heating value (28.8 MJ/kg versus diesel's 42.5 MJ/kg and 86% carbon). This advantage holds independent of feedstock, as it arises directly from molecular composition favoring oxidation over carbon. Empirical data from prototype heavy-duty engines confirm compliance with V standards for , PM, CO, and HC, with PM levels below detectable thresholds in some configurations. Fleet demonstrations, including LIFE projects and Asian bus trials (e.g., in ), validate these lab findings, showing ultra-low PM and smoke alongside controlled in real-world operation, though quantitative GHG reductions vary with engine calibration and load.

Lifecycle Assessment and Feedstock Dependencies

Lifecycle assessments (LCAs) of dimethyl ether (DME) reveal that (GHG) emissions vary significantly by feedstock, with fossil-derived routes generally comparable to or exceeding those of conventional diesel on a well-to-wheel basis. For DME produced from via , lifecycle GHG emissions typically range from 70 to 90 g CO₂-eq/MJ, aligning closely with diesel's approximately 94 g CO₂-eq/MJ benchmark when accounting for upstream extraction, reforming, and synthesis processes. Coal-based DME exhibits even higher footprints, often exceeding 100 g CO₂-eq/MJ due to intensive mining, gasification inefficiencies, and elevated leakage risks, offering no inherent CO₂ reduction without (CCS), which remains uneconomically scaled in most projects. Bio-DME from biomass gasification promises lower emissions of 10-30 g CO₂-eq/MJ when utilizing low-input waste residues, but actual figures frequently rise to 40-60 g CO₂-eq/MJ owing to energy-intensive preprocessing, transportation, and syngas upgrading, which can offset biogenic carbon credits. These pathways introduce feedstock dependencies beyond GHGs, including substantial water consumption—up to 11.3 L H₂O/MJ in coal gasification routes—and land use pressures for dedicated biomass crops, which compete with food production and exacerbate indirect land-use change emissions not always captured in simplified LCAs. Air quality benefits from DME combustion, such as reduced particulate matter (PM) and nitrogen oxides (NOx), hold across feedstocks due to its clean-burning oxygenate nature, independent of upstream sourcing. Indonesia's planned revival of coal-to-DME projects in 2025, backed by up to $1.2 billion in investments and special economic zones, underscores economic pragmatism over emission reductions, prioritizing domestic amid LPG shortages despite lacking integrated CCS to achieve net-zero claims. These initiatives, directed by President Prabowo Subianto's administration, highlight causal trade-offs: while substituting imported fuels, they perpetuate fossil dependencies without mitigating full-cycle CO₂ outputs, contrasting idealized narratives that overlook scalability and regional resource constraints.

History

Discovery and Initial Synthesis

Dimethyl ether (CH₃OCH₃) was first synthesized in 1835 by the French chemists Jean-Baptiste-André Dumas and Eugène-Melchior Péligot. Attempting to generate methylene (CH₂) from , they heated methyl alcohol with concentrated , yielding a colorless, flammable gas that they characterized as the simplest alkyl ether through and comparison to known ethers like . This product, boiling at -24 °C, was distinguished from and other volatiles by its low and lack of solubility, establishing it as a distinct compound with the formula C₂H₆O. Early characterization efforts built on this synthesis, confirming dimethyl ether's ether-like behavior, including its stability under certain conditions and reactivity in forming esters or halides. Chemists of the era, drawing from ether classification principles developed in prior decades, recognized it as the foundational member of the aliphatic series due to its symmetric structure and minimal carbon chain. Its gaseous state at further highlighted differences from higher homologs, aiding in refining organic and radical theories prevalent in 19th-century chemistry. Although primarily a laboratory product initially, dimethyl ether's extraterrestrial presence was identified in 1974 through observations of the . Lewis E. Snyder and colleagues detected emission lines from its rotational transitions, marking the first interstellar detection of a complex organic beyond simple hydrocarbons and alcohols, with abundances suggesting formation via gas-phase reactions in dense interstellar regions. This finding, verified by multiple transitions, underscored dimethyl ether's role in cosmic chemistry without reliance on terrestrial synthesis pathways.

Early Commercialization and Expansion

The aerosol application of dimethyl ether originated with Norwegian inventor Erik Rotheim's 1926 for a pressurized spray dispenser, which explicitly utilized DME as the to atomize liquids from a sealed vessel under sufficient for dispersion. Although the patent laid foundational groundwork for technology, commercial-scale production of high-purity DME for this purpose did not materialize until the mid-20th century, with Akzo Nobel pioneering its use as a in 1963 and German firm Union Kraftstoff GmbH achieving by 1966. Through the and , DME served in limited volumes—estimated globally at 100,000 to 150,000 tons annually by the late —primarily as a flammable but effective alternative to emerging chlorofluorocarbons in consumer spray products, though hydrocarbons like and dominated the market. Renewed focus on dimethyl ether as a emerged in the wake of the and 1979 oil crises, which spurred global efforts to develop synthetic alternatives to petroleum-derived diesel and (LPG), leveraging DME's high and low-soot combustion profile. Early industrial adoption prioritized coal-to-DME pathways in resource-rich regions; initiated pilot-scale plants in the 1980s deriving DME from via methanol dehydration, targeting household cooking to alleviate LPG shortages. By the 1990s, saw further expansion for LPG blending, where DME's compatibility enabled up to 20% volumetric mixes without engine modifications, supported by demonstration facilities that validated scalability. Key technological milestones included NKK Corporation's (predecessor to JFE Steel) early 1990s demonstrations in Japan, where a consortium developed direct one-step DME synthesis from syngas in slurry reactors, culminating in a 100 tons-per-day pilot plant in Hokkaido that confirmed economic viability for fuel-grade production. These efforts transitioned DME from niche propellant to viable energy carrier, with subsequent initiatives like Oberon Fuels' renewable DME program from biogas feedstocks building on this foundation to address decarbonization needs.

Developments and Research

Technological Innovations

Bifunctional catalysts combining methanol synthesis components, such as Cu/ZnO/Al₂O₃, with dehydration agents like zeolites or heteropolyacids enable direct conversion of syngas to dimethyl ether (DME) in a single reactor, enhancing overall process efficiency by minimizing intermediate handling and separation steps. These hybrid systems achieve DME selectivities exceeding 90% under optimized conditions, with metallic functions for CO hydrogenation and acidic sites for dehydration operating synergistically to suppress side products like higher hydrocarbons. Recent advancements include Pd/CeO₂/γ-Al₂O₃ formulations demonstrating stable DME yields up to 28.1% from at moderate temperatures around 250–300°C. For CO₂ utilization, integrated processes incorporate reverse water-gas shift (RWGS) reactions to generate CO intermediates, followed by bifunctional for DME formation, allowing renewable feedstocks like captured CO₂ and green H₂ to produce e-DME with carbon efficiencies improved through in-situ management. Pilot-scale demonstrations in the , such as the EU-funded POWERED , have validated these routes for renewable DME production, scaling to modular reactors with sorption-enhanced designs that boost CO₂ conversion rates by shifting equilibria via selective sorbents. Similarly, the BUTTERFLY initiative targets flexible rDME synthesis from biomass-derived , confirming operational stability in continuous flow tests. In engine applications, DME's low lubricity—stemming from its near-zero sulfur and aromatic content—necessitates additives at concentrations of 1000–2000 ppm to prevent wear in fuel injection systems, alongside material upgrades like hardened steels or coatings for compatibility. Demonstrations, including a 2023 DME-fueled tractor in India, employed lubricity enhancers and revised fuel delivery components, achieving reliable operation without excessive degradation. Optimized compression-ignition engines adapted for DME exhibit extended durability through superior atomization and high cetane numbers (>55), supporting prolonged runtime in genset configurations with minimal injector wear after additive treatment. The global dimethyl ether (DME) market was valued at approximately USD 7.2 billion in 2024, with projections indicating growth to USD 15.7 billion by 2033 at a (CAGR) of 8.1%, driven primarily by demand in for use as a (LPG) substitute and chemical feedstock. This expansion aligns with estimates of market value reaching USD 10-12 billion by 2030, fueled by increasing production capacities in coal-rich regions rather than widespread adoption of biomass-derived variants. In the United States, DME prices averaged around USD 1,090 per metric ton in late 2023 but rose to approximately USD 1,880 per metric ton by early 2025 amid supply constraints and feedstock volatility. Asia dominates DME production and consumption, with and leveraging abundant reserves for gasification-based synthesis, which accounts for the majority of output due to cost efficiencies over alternative feedstocks. 's coal-to-DME facilities, operational since the early , have scaled to meet domestic fuel blending needs, while 's initiatives target offsetting LPG imports equivalent to 15% of national demand through a proposed 1.4 million per year plant requiring 6 million s of annually. Fossil-derived routes, particularly , offer lower capital expenditures of USD 300-500 per of annual capacity compared to biomass pathways, which incur 76-93% higher production costs without subsidies or carbon pricing mechanisms. For instance, a -based DME plant's total operating costs can approach USD 470 per , undercutting biomass-to-DME economics absent policy interventions like taxes on emissions. Policy decisions underscore the pragmatic reliance on coal for DME scalability, as seen in Indonesia's March 2025 directive under President to revive projects for DME and , utilizing sovereign wealth funding and special economic zones to bypass import dependencies on intermittent renewable alternatives. These efforts highlight DME's role in , where coal's dispatchable prevails over subsidized but variable or electrolytic routes, though economic viability remains challenged by global price gaps—e.g., Indonesian DME sold at USD 460-508 per tonne in 2022-2023 against production costs exceeding USD 580 per tonne. Renewable DME (rDME) niches persist in under carbon taxation but represent marginal volumes globally, limited by elevated upfront investments and feedstock .

References

  1. https://pubchem.ncbi.nlm.nih.gov/compound/Dimethyl-Ether
  2. https://webbook.nist.gov/cgi/cbook.cgi?ID=C115106
  3. https://cameochemicals.noaa.gov/chemical/585
  4. https://afdc.energy.gov/files/pdfs/3608.pdf
  5. https://afdc.energy.gov/fuels/emerging-dme
  6. https://pubs.acs.org/doi/10.1021/acsomega.1c03885
  7. https://www.airgas.com/msds/001021.pdf
  8. https://webbook.nist.gov/cgi/cbook.cgi?ID=C115106&Mask=4
  9. https://www.inchem.org/documents/icsc/icsc/eics0454.htm
  10. https://encyclopedia.airliquide.com/dimethylether
  11. https://www.chemicalbook.com/ChemicalProductProperty_EN_CB8765901.htm
  12. https://cameochemicals.noaa.gov/chris/DIM.pdf
  13. https://webbook.nist.gov/cgi/cbook.cgi?ID=C115106&Mask=FFFFF
  14. https://www.mdpi.com/2073-4344/12/4/396
  15. https://link.springer.com/article/10.1007/s11244-022-01725-z
  16. https://f3centre.se/en/fact-sheets/dimethyl-ether-dme/
  17. https://www.chemeng.uliege.be/cms/c_4890527/fr/projetdme-finalreport
  18. https://www.sciencedirect.com/science/article/pii/S1385894723062253
  19. https://www.nature.com/articles/s41598-020-65296-3
  20. https://www.sciencedirect.com/science/article/abs/pii/S0926860X19302273
  21. https://pubs.acs.org/doi/10.1021/acssuschemeng.0c02557
  22. https://www.mdpi.com/2073-4344/14/5/308
  23. https://www.naun.org/main/NAUN/energyenvironment/2016/a682011-052.pdf
  24. https://www.toyo-eng.com/jp/en/solution/dme/
  25. https://scispace.com/pdf/catalytic-and-kinetic-study-of-methanol-dehydration-to-1z40jet60x.pdf
  26. https://pubs.acs.org/doi/10.1021/cs500967j
  27. https://www.mdpi.com/2073-4344/10/9/1071
  28. https://www.sciencedirect.com/science/article/abs/pii/S0021951715003486
  29. https://onlinelibrary.wiley.com/doi/10.1002/cite.202100167
  30. https://www.researchgate.net/publication/239412495_Determination_of_the_Optimum_Operating_Conditions_for_Direct_Synthesis_of_Dimethyl_Ether_from_Syngas
  31. https://pubs.acs.org/doi/10.1021/acs.iecr.0c01938
  32. https://www.pulpapernews.com/20191217/2030/worlds-first-biodme-inaugurated-sweden
  33. https://old.etipbioenergy.eu/value-chains/products-end-use/products/biodme
  34. https://ui.adsabs.harvard.edu/abs/2011FrEne...5..330W/abstract
  35. https://www.iea-amf.org/app/webroot/files/file/Annex%2520Reports/AMF_Annex_14_dme_bio.pdf
  36. https://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.4c00311
  37. https://pmc.ncbi.nlm.nih.gov/articles/PMC5943932/
  38. https://www.mdpi.com/2073-4344/12/11/1375
  39. https://dieselnet.com/tech/fuel_dme.php
  40. https://tc.canada.ca/en/programs/non-funding-programs/ecotechnology-vehicles-program/dimethyl-ether-fuel-literature-review
  41. https://www.thaiscience.info/journals/Article/IIRE/10895219.pdf
  42. https://www.jstage.jst.go.jp/article/jsaereview/30/3/30_3_329/_pdf/-char/ja
  43. https://eureka.patsnap.com/report-dimethyl-ether-in-automotive-enhancing-fuel-efficiency
  44. https://www.precedenceresearch.com/dimethyl-ether-and-renewable-dme-market
  45. https://indonesiabusinesspost.com/3837/business-and-investment/government-plans-coal-to-dme-project-but-funding-risks-raise-concerns
  46. https://www.reuters.com/business/energy/indonesia-offer-energy-projects-worth-40-billion-2025-minister-says-2025-03-04/
  47. https://old.etipbioenergy.eu/images/dme-fact-sheet.pdf
  48. https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=3022&context=iracc
  49. https://www.researchgate.net/publication/336325124_Computation_of_Ecological_Properties_Flammability_Properties_and_Thermodynamic_Properties_of_Sustainable_Refrigerant_Dimethylether_RE170_Using_Martin_Hou_Equation_of_State_MHEOS
  50. https://www.sciencedirect.com/science/article/pii/S0140700725001902
  51. https://www.nouryon.com/globalassets/inriver/resources/technical-bulletin-personalcare-dimethyl-ether-global-en.pdf
  52. https://gasesgrit.com/en/the-advantages-of-dimethyl-ether-dme/
  53. https://www.verifiedmarketreports.com/product/dme-aerosol-propellant-market/
  54. https://diversifiedcpc.com/wp-content/uploads/2021/12/hp-dme-technical-information.pdf
  55. https://pubs.acs.org/doi/10.1021/acsomega.4c11491
  56. https://www.mdpi.com/2297-8739/12/7/169
  57. https://www.sciencedirect.com/science/article/pii/S2369969824000501
  58. https://www.sciencedirect.com/science/article/abs/pii/S0921344921002500
  59. https://www.mdpi.com/2073-4344/9/5/485
  60. https://www.sciencedirect.com/science/article/abs/pii/S1875510015303231
  61. https://www.sciencedirect.com/science/article/abs/pii/S0956053X21005225
  62. https://link.springer.com/article/10.1007/s00217-022-04122-8
  63. https://journals.sagepub.com/doi/pdf/10.1177/07482337221125071
  64. https://www.chemours.com/ja/-/media/files/propellants/hp-dme-toxicity-summary.pdf
  65. https://pubmed.ncbi.nlm.nih.gov/36190179/
  66. https://journals.sagepub.com/doi/abs/10.1177/07482337221125071
  67. https://efsa.onlinelibrary.wiley.com/doi/pdf/10.2903/j.efsa.2015.4174
  68. https://www.fda.gov/media/113335/download
  69. https://academic.oup.com/jat/article-abstract/39/5/415/761124
  70. https://chemicalsafety.ilo.org/dyn/icsc/showcard.display?p_card_id=0454
  71. https://nj.gov/health/eoh/rtkweb/documents/fs/0758.pdf
  72. https://www.researchgate.net/figure/apor-pressure-curve-of-Dimethylether_fig1_325015130
  73. https://pubs.acs.org/doi/abs/10.1021/acsomega.1c02837
  74. https://www.aiche.org/resources/publications/cep/2017/december/process-safety-beacon-liquefied-gases-can-be-hazardous
  75. https://www.mdpi.com/2077-1312/8/5/316
  76. https://dergipark.org.tr/en/download/article-file/2255298
  77. https://pmc.ncbi.nlm.nih.gov/articles/PMC8756441/
  78. https://afdc.energy.gov/files/u/publication/ornl_dme_tm-2014-59.pdf
  79. https://www.sciencedirect.com/science/article/abs/pii/S0360128512000597
  80. https://webgate.ec.europa.eu/life/publicWebsite/project/LIFE05-ENV-S-000405/demonstration-of-demethyl-ether-vehicle-for-sustainable-transport
  81. https://www.sciltp.com/journals/ijamm/articles/2504000088
  82. https://www.frontiersin.org/journals/sustainability/articles/10.3389/frsus.2022.1057190/full
  83. https://pmc.ncbi.nlm.nih.gov/articles/PMC10089250/
  84. https://www.researchgate.net/publication/223384789_A_Life_Cycle_Analysis_on_a_Bio-DME_production_system_considering_the_species_of_biomass_feedstock_in_Japan_and_Papua_New_Guinea
  85. https://www.sciencedirect.com/science/article/abs/pii/S0016236123024985
  86. https://www.sciencedirect.com/science/article/abs/pii/S0959652615015565
  87. https://ieefa.org/resources/economics-behind-indonesias-dimethyl-ether-dme-push-are-hard-justify
  88. https://www.petromindo.com/news/article/indonesia-to-revive-coal-to-dme-projects-with-1-2b-investment-plan-sez
  89. https://english.news.cn/asiapacific/20250731/31b942e1b8244af5a61967e0341d2225/c.html
  90. https://www.drugfuture.com/chemdata/methyl-ether.html
  91. https://adsabs.harvard.edu/full/1974ApJ...191L..79S
  92. https://patents.google.com/patent/US1800156A/en
  93. https://www.sciencedirect.com/science/article/abs/pii/S0926337317305222
  94. https://www.dawsom.com/4-tips-you-should-know-using-dme-as-the-aerosol-propellant/
  95. https://www.sciencedirect.com/science/article/abs/pii/S1875510012000650
  96. https://www.researchgate.net/publication/239424271_Pilot-scale_commercial_DME_production_and_utilization_as_a_household_fuel_in_China
  97. https://www.jfe-steel.co.jp/en/research/report/008/pdf/008-06.pdf
  98. https://crimsonpublishers.com/pps/fulltext/PPS.000543.php
  99. https://www.oberonfuels.com/oberon-fuels-starts-commercial-production-of-renewable-dme
  100. https://pubs.acs.org/doi/10.1021/acs.iecr.1c03046
  101. https://www.sciencedirect.com/science/article/pii/S0926337317305222
  102. https://onlinelibrary.wiley.com/doi/10.1002/anie.202423273
  103. https://hal.science/hal-03647214/document
  104. https://www.tno.nl/en/newsroom/2023/09/powered-renewable-dme/
  105. https://cordis.europa.eu/project/id/101118241
  106. https://openaccess.city.ac.uk/id/eprint/15549/1/he%2520potential%2520of%2520di-methyl%2520ether%2520%2528DME%2529%2520as%2520an%2520alternative%2520fuel%2520for%2520compression-ignition%2520engines.pdf
  107. https://dst.gov.in/countrys-first-dimethyl-ether-fuelled-tractor-ushers-new-era-clean-fuel-applications
  108. https://www.sciencedirect.com/science/article/abs/pii/S0016236124004472
  109. https://www.imarcgroup.com/dimethyl-ether-market
  110. https://www.theinsightpartners.com/reports/dimethyl-ether-market
  111. https://www.imarcgroup.com/dimethyl-ether-pricing-report
  112. https://www.openpr.com/news/4046206/dimethyl-ether-dme-price-fluctuation-2025-price-index-chart
  113. https://www.mordorintelligence.com/industry-reports/dimethyl-ether-market
  114. https://www.researchgate.net/figure/DME-Plant-CAPEX-Estimation-Year-2017_tbl1_329189958
  115. https://www.sciencedirect.com/science/article/pii/S0378382012003451
  116. https://ieefa.org/wp-content/uploads/2020/11/Proposed-DME-Project-in-Indonesia-Does-Not-Make-Economic-Sense_November-2020.pdf
  117. https://news.mongabay.com/2025/03/indonesia-coal-gasification-emissions-fossil-fuels-mining-climate-change-danantara/
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