Uses of dimethyl ether

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I have just started working in the dimethyl ether industry, and I have been learning about dimethyl ether recently. These are some materials I found; I’d like to share them with everyone, and I hope you can all offer me your guidance. (1) As a substitute for liquefied petroleum gas, dimethyl ether has the following advantages when used as a fuel for household use: it contains oxygen, has a short carbon chain, burns completely and safely, does not produce carbon deposits during combustion, generates no black smoke, leaves no residue, and its combustion exhaust meets ** standards. Dimethyl ether is easy to compress; at room temperature, the storage pressure is 0.61 MPa, which is lower than the 1.6 MPa of liquefied petroleum gas. Therefore, it is safer. Moreover, existing containers and pipelines such as liquefied petroleum gas tanks and tanks can be used, and stoves can also be utilized, making its adoption easier. (2) As a blending component for other civilian fuels, adding a certain amount of dimethyl ether to liquefied petroleum gas not only improves the vaporization efficiency of C5 but also enhances the miscibility among C3, C4, and C5, thereby eliminating residual liquid in the liquefied gas cylinders and preventing carbon deposition during combustion, which brings considerable economic benefits. The calorific value of dimethyl ether is 64,686 kJ/Nm3. By adding a certain proportion of dimethyl ether to city gas with a calorific value of 15,907 kJ/Nm3 or to natural gas with a calorific value of 37,674 kJ/Nm3, it is possible to address the issue of insufficient gas supply during peak times in city gas supply, reduce the CO content in city gas, enhance safety in use, improve the quality of the gas, and increase its calorific value. (3) Alcohol-ether fuels: Alcohol-ether fuels are mixtures composed of methanol and dimethyl ether in specific proportions. Since crude ether contains water generated during the dehydration of methanol, dimethyl ether is fully miscible with both methanol and water. Furthermore, since dimethyl ether can generate a certain partial pressure and turns into a gas under reduced pressure, alcohol-ether fuels overcome the limitations of pure alcohol fuels, which require air compression or self-pressurization as well as preheating; this improves their combustion performance, endowing them with the advantages of being clean, burning completely, and easy to use. Alkyl ether fuel is a civilian fuel unique to China, capable of meeting the demands that cannot be satisfied by liquefied petroleum gas and city gas supplies. (4) Another important use of dimethyl ether is as a fuel for vehicles, as a substitute for diesel. (5) As a substitute for gasoline, the octane number of ether-based blended gasoline prepared from dimethyl ether is not less than 91.6. Xi’an Jiaotong University has conducted bench tests and road testing, and the results have shown good environmental and social benefits. 1.2.2 Applications of dimethyl ether in the fine chemical industry (1) Use as a propellant in aerosol products. Chlorofluorocarbons such as Freon (ODP=1) were widely used as propellants in aerosols, but they damage the ozone layer in the atmosphere; the Earth Summit in Rio de Janeiro called for their prohibition. Dimethyl ether (ODP=0) degrades rapidly in the atmospheric troposphere and is harmless to the ozone layer; it has now replaced chlorofluorocarbons on a large scale in aerosol products. As a propellant, it has the following advantages: ① It does not pollute the environment, with an ozone depletion coefficient of zero ； ②It exhibits good miscibility with various resins and solvents; its excellent water solubility (34% solubility in water) and alcohol solubility (it becomes miscible with water when 6% ethanol is added) enable it to serve both as a propellant and as a solvent in aerosol formulations ； ③It has low toxicity, and no adverse effects have been observed when used in cosmetics ； (2) Use as a refrigerant and blowing agent: Dimethyl ether has a low boiling point, a large latent heat of vaporization, and excellent vaporization properties. Its condensation and evaporation characteristics are similar to those of chlorofluorocarbons, making it very promising as a refrigerant. Currently, both domestically and internationally, efforts are being made to develop the use of dimethyl ether in refrigerators, air conditioners, and food preservation, as a substitute for fluorocarbons that damage the ozone layer in the atmosphere. (3) Used as a basic raw material in the organic chemical industry and for power generation. As a basic raw material in organic chemistry: ① Oxidation to produce formaldehyde; ② Methylation to produce dimethyl sulfate; ③ Ammonolysis to produce dimethylamine; ④ Reaction with hydrogen chloride to produce chloromethane; ⑤ Carbonylation to produce acetic anhydride; ⑥ Carbonylation to produce vinyl acetate. For power generation, the calorific value of each ton of dimethyl ether is 28.89 GJ, and with an efficiency of 50% for gas turbine power generation, it is possible to produce approximately 4420 kWh of electricity. (4) Used for producing low-carbon olefins. Ethylene and propylene are fundamental raw materials in the petrochemical industry; to address the issue of the source of these basic raw materials, foreign countries place great emphasis on integrating coal chemistry, natural gas chemistry, and petrochemistry. The former Soviet Union studied the production of reagent-grade ethylene from dimethyl ether, achieving yields of >85%. In the process developed by DuPont for the dehydration of dimethyl ether to produce low-carbon olefins, the yields of ethylene and propylene are 60% and 25%, respectively, with a dimethyl ether conversion rate of 87%. Pilot-scale tests conducted at the Dalian Institute of Chemical Physics, part of the Chinese Academy of Sciences, have achieved a yield of low-carbon olefins of over 100 grams per cubic meter. Currently, the process of producing olefins from dimethyl ether, developed by some foreign chemical companies, is nearing industrialization.