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1. Properties and uses: Alias of dimethyl ether: English name of methyl ether: methyl ether ； dimethyl ether ； DME CAS number: 115-10-6 Molecular formula: C2H6O structural formula: CH3—O—CH3 Dimethyl ether is also called methyl ether, or DME for short. Dimethyl ether is a colorless gas or compressed liquid under normal pressure with a slight ether aroma. The relative density (20℃) is 0.666, the melting point is -141.5℃, the boiling point is -24.9℃, and the vapor pressure at room temperature is about 0.5MPa, which is similar to liquefied petroleum gas (LPG). Soluble in water and various organic solvents such as alcohol, ether, propylene glycol, and chloroform. It is flammable, the flame is slightly bright when burning, and the heat of combustion (gaseous state) is 1455kJ/mol. DME is inert at room temperature, not prone to auto-oxidation, non-corrosive, and non-carcinogenic, but it can decompose into methane, ethane, formaldehyde, etc. under radiation or heating conditions. Dimethyl ether is a homolog of ether, but it is used * * The ether used in the agent is different and has extremely low toxicity. ； Can dissolve various chemicals ； Due to its easy compression, condensation, vaporization and miscibility with many polar or non-polar solvents, it is widely used in aerosol product propellants, Freon replacement refrigerants, solvents, etc. It can also be used in chemical synthesis and has a wide range of uses. As a basic chemical raw material, dimethyl ether has many unique uses in chemical industries such as pharmaceuticals, fuels, and pesticides due to its good properties of easy compression, condensation, and vaporization. For example, high-purity dimethyl ether can be used as aerosol propellant and refrigerant instead of Freon, reducing pollution to the atmospheric environment and damage to the ozone layer. Due to its good water solubility and oil solubility, its range of applications * * Better than petrochemicals such as propane and butane. Replacing methanol as a new raw material for formaldehyde production can significantly reduce formaldehyde production costs, and shows its superiority in large-scale formaldehyde installations. As a civil fuel gas, its storage, transportation and combustion safety, premixed gas calorific value and theoretical combustion temperature are better than petroleum liquefied gas. It can be used as peaking gas and liquefied gas blending gas for urban pipeline gas. It is also an ideal fuel for diesel engines. Compared with methanol fuel vehicles, there is no cold start problem. It is also one of the main raw materials for producing low-carbon olefins in the future. Due to the shortage of petroleum resources, the abundance of coal resources and the increasing awareness of people's environmental protection, dimethyl ether has received increasing attention as a clean fuel converted from coal, and has become a carbon-one chemical product with superior performance that has been competitively developed at home and abroad in recent years. As an alternative fuel to LPG and petroleum, dimethyl ether is a chemical with similar physical properties to LPG. It does not produce environmentally damaging gases when burned and can be produced cheaply and in large quantities. Like methane, it is expected to become one of the energy sources of the 21st century. In short, the unique physical and chemical properties of dimethyl ether have established its basic industrial status in the international and domestic markets, and can be widely used in industry, agriculture, medical care, daily life and other fields. In the future, dimethyl ether will be mainly used to replace automobile fuel, liquefied petroleum gas, city gas, etc. The market prospect is extremely broad and it is currently an industry that is prioritized for international and domestic development. 2. Production methods: The current main production methods include methanol dehydration to produce dimethyl ether and synthesis gas to produce dimethyl ether in one step. ? 1 The production of dimethyl ether by dehydration of methanol is divided into liquid phase method and gas phase method. At present, all domestic production equipment adopts this method. The liquid phase method is to heat a mixture of sulfuric acid and methanol, and dehydrate the methanol to produce dimethyl ether. Due to the strong corrosiveness and serious pollution of sulfuric acid, it has been gradually eliminated. In recent years, Shandong Luming Chemical Co., Ltd. has improved the liquid phase method, changed the composition of the acidic medium, obtained its own intellectual property rights, and is building a large-scale dimethyl ether production device. The gas phase method is to pass methanol vapor through a molecular sieve catalyst to catalytically dehydrate it to obtain dimethyl ether. This method is a gas-solid phase catalytic reaction plus distillation process. There are domestic studies in this area, and a kiloton-level production process has been developed based on these studies. ? 2 The one-step synthesis of dimethyl ether from synthesis gas is divided into gas phase method and three-phase method, which are methods under research and development. In the gas phase method, synthesis gas reacts on the surface of a solid catalyst ； The three-phase method is the slurry method, in which the synthesis gas diffuses to the surface of the catalyst suspended in an inert solvent for reaction. In the gas phase method, the conversion rate of synthesis gas in the reactor is low, the circulation volume of unreacted synthesis gas is large, and the use of hydrogen-rich synthesis gas (H2/CO is greater than 2) is required. The single-pass conversion rate of the three-phase method is higher than that of the gas-phase method, and it has high selectivity and low energy consumption. It can increase the output of DME and reduce costs. It is a new method worthy of development and has important economic and social benefits. Therefore, the research on the one-step production of dimethyl ether from synthesis gas is the current direction of dimethyl ether technology development.