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What is dimethyl ether gas?
Dimethyl ether gas can also be called methylether, dme dimethyl ether, gas dme, dme ether, or DME for short, with a simplified structure of CH3OCH3 and a molecular weight of 46.07. Methyl ether is a colorless gas or compressed liquid under normal pressure, with a slight ether fragrance. Melting point -141°C, boiling point -29.5°C. Soluble in water and various organic solvents such as alcohol, ether, acetone, chloroform, etc. Flammable, the flame is slightly bright when burning. DME is inert at room temperature, not easy to auto-oxidize, non-corrosive, non-carcinogenic, but it can be decomposed into methane, ethane, formaldehyde, etc. under radiation or heating conditions.
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Physical and chemical properties of dimethyl ether gas Appearance: Colorless gas with ether-specific odor. Melting point: -141°C Boiling point: -29.5°C Density (liquid): 0.666g/cm3 Density (gas): 1.97kg/m3 Saturated vapor pressure: 533.2kPa (20°C) Heat of combustion: -1453kJ/mol Critical temperature: 127°C Critical pressure: 5.33MPa Octanol/water partition coefficient: 0.10 Flash point: -89.5°C Ignition temperature: 350°C Upper limit of explosion (V/V): 27% Lower explosion limit (V/V): 3.4% Solubility: Soluble in water, ethanol, ether. Refractive index (20ºC): 1.3018 Gas viscosity (20ºC): 85.1mPa·s Heat of fusion: 107.3kJ/kg Heat of formation (gas state): -185.5kJ/mol Critical Compression Factor: 0.270 Eccentricity factor: 0.204 Solubility parameter: 17.572(J cm-3)0.5 Gas phase standard combustion heat (enthalpy): -1460.5kJ·mol-1 Gas phase standard claims heat (enthalpy): -184.1kJ·mol-1 Gas phase standard entropy: 267.34J·mol-1·K-1 Gas phase standard formation free energy: -112.9kJ·mol-1 Gas phase standard hot melt: 65.57J·mol-1·K-1 |
Numbering system for dimethyl ether gas MDL number: MFCD00008494 RTECS number: PM4780000 BRN number: 1730743
Molecular structure data of dimethyl ether gas Molar refractive index: 13.15 Molar volume (cm3/mol): 67.9 Isotonic specific volume (90.2K): 131.3 Surface tension (dyne/cm): 14.0 Polarizability (10-24cm3): 5.17
Calculated chemical data of dimethyl ether gas Hydrophobic parameter calculation reference value (XlogP): 0.1 Number of hydrogen bond donors: 0 Number of hydrogen bond acceptors: 1 Number of rotatable bonds: 0 Number of tautomers: 0 Topological Molecular Polar Surface Area: 9.2 Number of heavy atoms: 3 Surface charge: 0 Complexity: 2.8 Number of isotope atoms: 0 Determine the number of stereocenters: 0 Uncertain number of stereocenters: 0 Determine the number of bond stereocenters: 0 Uncertain number of bond stereocenters: 0 Number of covalent bond units: 1 |
Toxicological data for dimethyl ether gas
1. Acute toxicity: Rat inhalation LD50: 308mg/m3.
2. Other multi-dose toxicity: rats inhaled TDLo: 2pph/6h/30W-I;
3. Inhalation can inhibit the central nervous system. After inhalation, it can cause anesthesia and suffocation, and the anesthesia effect is weaker than ether. Irritating to skin. Mixing with air can form an explosive mixture, and the allowable concentration in air is 400mg/kg.
4. Subacute and chronic toxicity: Rats inhaled 2% methyl ether, 6 hours a day, 5 days a week, 30 weeks, weight gain, no obvious abnormalities were found in blood, urine and histopathological examination, but serum alanine and Increased aspartate and aspartate aminotransferase indicate hepatotoxicity.
Applications of dimethyl ether gas
1. Vehicle fuel
As a vehicle fuel to replace diesel, it is the main field of industrial application of dimethyl ether at present. Generally, the thermal efficiency of diesel engines is 7%-9% higher than that of gasoline engines, but existing diesel engines are gradually being eliminated due to high pollution. The diesel engine using dimethyl ether as fuel is gradually replacing the original diesel engine due to its advantages of high efficiency and environmental protection.
The power of dimethyl ether engine is higher than that of diesel engine, which can reduce noise, realize smokeless combustion, meet the requirements of environmental protection, and is an ideal substitute fuel for diesel. After oxidative coupling of dimethyl ether, a fuel additive with a cetane number of 60-100 can be synthesized. At normal temperature, the additive can be compatible with diesel oil in any proportion, and can be made into fuel with a cetane number of 41-57.
Vehicles using dimethyl ether can become dual-fuel vehicles that can burn both oil and gas without changing the structure and performance of the original vehicle. The installation of the gas supply system is convenient and easy, and its installation cost and the cost of building a gas filling station are lower than those of LPG and CNG fuel vehicles.
2. Civil fuel
Due to the similar physical properties of dimethyl ether to liquefied petroleum gas, complete combustion and less pollutants, dimethyl ether has a huge market as a new type of civil clean fuel. It can be used as civil fuel in large and medium-sized cities where there is no shortage of LPG and CNG resources. The purity of fuel-grade dimethyl ether is generally 98%, and the rest is methanol, C3-C4 hydrocarbons, and water, which can ensure that bottled dimethyl ether burns out at normal room temperature. DME has the following advantages as a civil fuel.
(1) DME can be liquefied at room temperature, and the pressure of the gas cylinder meets the requirements of existing liquefied petroleum gas, and can be stored in existing liquefied petroleum gas tanks.
(2) Dimethyl ether, like LPG, is a gaseous fuel, easy to use, no need to preheat, and it can be opened whenever it is used.
(3) The composition of dimethyl ether is stable and there is no residual liquid, which can ensure the effective use of users.
(4) DME has better combustion characteristics than LPG, and no dangerous gas will be produced during combustion.
(5) Fuel-grade dimethyl ether (DME>98%) can be used for civilian use, and its performance will not be affected during transportation, storage and use, and it is safe and reliable.
(6) The price of DME stoves and LPG stoves of the same grade is the same. If you need to refit old LPG stoves, you only need to spend a small amount on each stove.
3. Cutting Fuel
Dimethyl ether replaces acetylene as the cutting fuel, which is exactly the same as the cutting equipment that uses acetylene as the fuel, and has good cutting performance, smooth cutting surface, no need for polishing and grinding, which can save a lot of manpower. Compared with the use of acetylene fuel, it can save more than 60% of the cost: Substituting a large amount of dimethyl ether for acetylene for cutting can reduce the production of high-pollution and high-energy-consuming calcium carbide, which is conducive to energy saving and environmental protection.
4. Dimethyl ether power generation
DME is a clean fuel that can be used to generate electricity. Since a large amount of low-priced coal in my country is used for power generation in power plants, DME has not been given priority at present. However, if my country plans to use natural gas to generate electricity, it should be analyzed to determine the competitiveness of DME and natural gas in the power generation market.
5. Heating and bathing
Dimethyl ether is used as fuel for household heating, bathing, etc. in areas that do not have central heating conditions. It is characterized by a short heating time, generally only 8-15s, and can adjust the water temperature according to needs, can quickly provide hot water, long use time, low price, and has the advantages of energy saving, environmental protection, high efficiency, and safety.
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