Production and applications of dimethyl ether in China

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Dimethyl ether, abbreviated as DME, is a colorless gas or compressed liquid at room temperature. Its structural formula is CH30CH3; the density at 20°C is 66 l/kg·m3, the boiling point is –24.9°C, the heat of combustion is 31583 KJ/kg, the specific heat is 2.24 KJ/kg·K, the molecular weight is 46.07, and the freezing point is –14.15°C. Vapor pressure (20°C): 0.53 MPa. Heat of vaporization (-24.8°C): 467.4 KJ/kg. The explosive limit in air at 8°C is 3.45–26.7%. Dimethyl ether is soluble in water, carbon tetrachloride, propane, chloroform, methyl acetate, etc. Dimethyl ether is an important downstream product of methanol, boasting unique advantages: it is non-corrosive to metals, maintains good stability in high-temperature and high-humidity environments, and does not contain chlorofluorocarbons. It serves as an ideal substitute for Freon and plays a positive role in protecting the atmospheric ozone layer, making it an excellent environmentally friendly product. Dimethyl ether has shown good performance in aerosol products as a substitute for Freon. Currently, dimethyl ether is mainly used in spray paints, hair gels, air fresheners, automotive aerosols, insecticidal aerosols, and in the production of high-purity dimethyl sulfate. Dimethyl ether is also used as a solvent and extractant in dye production and other chemical industries. Dimethyl ether has also been successfully tested as a refrigerant; it offers the advantages of low cost and good cooling performance. 1. Production of dimethyl ether: Currently, the main methods for producing dimethyl ether are the methanol method and the syngas method. (1) Production of dimethyl ether by gas-phase dehydration of methanol: Methanol is converted into dimethyl ether through gas-phase dehydration, with by-products such as CO, CO2, CH4, C2H2, and H2 also being produced. Active alumina, 13X molecular sieve, and ZSM-5 molecular sieve can all be used as catalysts for the gas-phase dehydration of methanol. When a ZSM-5 molecular sieve catalyst is used, the reaction takes place at around 200°C, with a methanol conversion rate of 75–85%. Reported on 2007-03-04 11:40:20: Production and applications of dimethyl ether in China. Dimethyl ether, also known as methyl ether, is a colorless gas or compressed liquid at room temperature. Its structural formula is CH30CH3; the density at 20°C is 66 l/kg·m3, the boiling point is –24.9°C, the heat of combustion is 31583 KJ/kg, the specific heat is 2.24 KJ/kg·K, the molecular weight is 46.07, and the freezing point is –14.15°C. Vapor pressure (20°C): 0.53 MPa. Heat of vaporization (-24.8°C): 467.4 KJ/kg. The explosive limit in air at 8°C is 3.45–26.7%. Dimethyl ether is soluble in water, carbon tetrachloride, propane, chloroform, methyl acetate, etc. Dimethyl ether is an important downstream product of methanol, boasting unique advantages: it is non-corrosive to metals, maintains good stability in high-temperature and high-humidity environments, and does not contain chlorofluorocarbons. It serves as an ideal substitute for Freon and plays a positive role in protecting the atmospheric ozone layer, making it an excellent environmentally friendly product. Dimethyl ether has shown good performance in aerosol products as a substitute for Freon. Currently, dimethyl ether is mainly used in spray paints, hair gels, air fresheners, automotive aerosols, insecticidal aerosols, and in the production of high-purity dimethyl sulfate. Dimethyl ether is also used as a solvent and extractant in dye production and other chemical industries. Dimethyl ether has also been successfully tested as a refrigerant; it offers the advantages of low cost and good cooling performance. 1. Production of dimethyl ether: Currently, the main methods for producing dimethyl ether are the methanol method and the syngas method. (1) Production of dimethyl ether by gas-phase dehydration of methanol: Methanol is converted into dimethyl ether through gas-phase dehydration, with by-products such as CO, CO2, CH4, C2H2, and H2 also being produced. Active alumina, 13X molecular sieve, and ZSM-5 molecular sieve can all be used as catalysts for the gas-phase dehydration of methanol. When a ZSM-5 molecular sieve catalyst is used, the reaction takes place at around 200°C; the conversion rate of methanol can reach 75–85%, with a selectivity for dimethyl ether exceeding 99%. After the gas-phase reaction in stage A, the products are separated by condensation; the gas-phase product is almost pure dimethyl ether. The liquid phase contains methanol and water, with the methanol being recovered for reuse. (2) Production of dimethyl ether from syngas: Methanol is synthesized from syngas using a copper-based catalyst, and then dimethyl ether is produced by the dehydration of methanol; this is known as the two-step process ； The direct production of dimethyl ether from syngas involves the simultaneous occurrence of methanol synthesis and methanol dehydration processes on a bifunctional catalyst. The production of dimethyl ether from syngas in China is still in the pilot stage. In the production of dimethyl ether from syngas, the product contains methanol, CO, and CO2. Methanol is dehydrated to dimethyl ether, and the purity of the gaseous dimethyl ether is very high, approaching 100%. Therefore, the methanol dehydration route is suitable for producing high-purity dimethyl ether. Currently, the world’s total production capacity for dimethyl ether is approximately 150,000 tons per year, with an output of around 100,000 tons per year. Most of it is used in the aerosol industry. Due to the ban and restrictions on the use of chloroalkanes in recent years, it is estimated that the global demand for dimethyl ether in the year 2000 will be around 130,000 tons per year. The countries and regions where consumption exceeds 10,000 tons include the United States, Japan, France, Italy, Germany, and China. For a long time, China has relied on imports for dimethyl ether; current production is only around 7,000 tons per year, while the domestic demand for dimethyl ether is approximately 20,000 tons per year. In 2000, China’s demand for dimethyl ether was around 30,000 tons per year. As the applications of dimethyl ether are expanding increasingly, the market holds great potential. Currently, several manufacturers in China are already producing dimethyl ether; among them, Guangdong Zhongshan Fine Chemical Industry Co., Ltd. has a large production capacity of 2,500 tons per year ； Yiwu Guangyang Chemical Industry Co., Ltd. has a production capacity of 2,500 tons per year, and is currently the largest dimethyl ether producer in East China ； The Fertilizer Factory in Mengcheng County, Anhui Province, has built a production facility for high-purity dimethyl ether with an annual capacity of 2,500 tons. The Shanghai Research Institute of Petrochemical Technology has built an 800-ta plant, and an industrial demonstration plant for dimethyl ether with a capacity of 1,000 t/a has been established in Kunshan, Jiangsu. In addition, the Wuhan Sulfuric Acid Plant also has a dimethyl ether production facility. 2. Applications of dimethyl ether Dimethyl ether is the simplest fatty ether and a chemical product with a wide range of applications. It is mainly used as a propellant in aerosols. It serves as a substitute for Freon as a refrigerant, solvent, extractant, and alcohol-ether fuel. Furthermore, it can also be used as an insecticide, spray paint, polishing agent, rust inhibitor, alkylation reagent, and halogenation reagent, as well as as a catalyst and stabilizer for polymers. At low pressure, it can be liquefied into a high-quality new type of liquefied gas that is pollution-free, leaves no residue, and is non-explosive; it can help protect the atmosphere. Dimethyl ether is used in the aerosol industry, and can gradually replace compressed gases such as Freon and butane. It is widely used as a propellant in the dispersion of spray products. Dimethyl ether has a high cetane number, offering good combustion properties as a diesel alternative, with emissions that are even lower than those required by California’s ultra-low emission standards. Dimethyl ether has properties similar to liquefied petroleum gas, and can replace it as a clean fuel for domestic use. In recent years, due to environmental protection requirements, the ban on chlorofluorocarbons and the development of alternatives have become urgent. China will completely ban the use of Freon in 2010. Dimethyl ether has physical properties similar to those of Freon, making it one of the most ideal alternatives to Freon. It is widely used as a propellant in various sprays, which has led to rapid development in its production, particularly abroad. Shanxi Jia New Energy Chemical Industry Co., Ltd. is at the leading level in China in terms of technology related to clean alternative fuels – methanol-powered vehicles. The company collaborates with domestic research institutions and universities, and it is the responsible party for the **Demonstration Project on Methanol-Powered Vehicles as Clean Fuels. In the near future, a technological innovation system will be established, with clean energy production and application as its core elements, including methanol fuel and vehicles, dimethyl ether production and its use as a substitute for diesel, dimethyl ether as a substitute for liquefied petroleum gas, and methanol fuel cells. With the support of Ford Motor Company in the United States and the National Natural Science Foundation of China, the Automotive Engineering System at the School of Energy and Power Engineering of Xi’an Jiaotong University has, through nearly three years of intensive research, utilized a new type of diesel alternative fuel – dimethyl ether – to achieve ultra-low emissions from diesel engines. These emission levels not only meet the European Standard 2 and Standard 3 requirements but are also close to the emission standards that will come into effect in Europe in 2005, as well as the ultra-low emission standards in California, United States. The research results show that, compared to diesel engines, the use of dimethyl ether eliminates carbon soot emissions entirely; nitrogen oxide (NOx) emissions are reduced by 50–70%, unburned hydrocarbons emissions are reduced by 30%, and carbon monoxide (CO) emissions are reduced by 20%. This research achievement fills a gap in China’s field of research on ultra-low emission vehicles, placing it at the forefront internationally. At present, Xi’an Jiaotong University is working to apply this technology to diesel vehicles, and will soon introduce China’s first ultra-low emission vehicle. When used as a refrigerant for freezing food, dimethyl ether helps to eliminate unpleasant odors and smells. If it is successfully adopted in the refrigeration industry, its usage will increase significantly, and this will represent the most important potential market for dimethyl ether. It is reported that refined petroleum liquefied gas and dimethyl ether have been widely used as alternatives to Freon propellants. At present, China has established three aerosol filling centers in Shanghai, Tianjin, and Zhongshan in Guangdong, with an annual filling capacity of 95 million cans, and an annual capacity to replace fluorocarbons of over 16,000 tons. The Shanghai Jiale Aerosol Wine Packaging Center produces 3,000 tons of refined propane and butane gases per year, with an annual filling capacity of 30 million cans; these can replace 6,300 tons of Freon ； Guangdong Zhongshan Fine Chemical Company has built a dimethyl ether plant with an annual capacity of 2,500 tons. In addition, Shanghai CCL Aerosol Propellant Manufacturing and Filling Co., Ltd. was established through joint investment by Pudong Waigaoqiao Free Trade Zone New Development Co., Ltd., Yangyuan Town in Pudong New Area, Canadian CCL Industrial Group Inc., and U.S.-based CCL Company. The company has an annual production capacity of 10,000 tons of fluorine-free aerosol propellants, 20 million cans of aerosol products, and 15 million cans of liquid products. The Natural Gas Production and Sales Plant of Zhongyuan Oilfield develops and produces propellants—isobutane, n-butane, and propane—and has become the largest production site in Asia for fluorine-free raw materials used in aerosols; a phase I facility with an annual capacity of 50,000 tons has already been built. To date, in the industrially developed countries around the world, the aerosol industry has developed into a distinct sector, with its products accounting for a significant portion of the gross national product. Currently, chlorofluorocarbons are primarily used as propellants in aerosols. However, due to their severe damage to the ozone layer in the atmosphere, dimethyl ether is considered an ideal alternative propellant for aerosols – its properties are similar to those of CFCs, its production technology is not overly complex, it has low costs, requires minimal investment, and its price is reasonable. Therefore, it is imperative to rapidly develop processes for manufacturing dimethyl ether. Because this project brings significant social and economic benefits in terms of curbing air pollution and improving the environment in which humans live. 3. Market prospects for dimethyl ether: It has become imperative to replace fluorocarbons with refrigerants that are harmless to the environment. Given that dimethyl ether has properties very similar to those of fluorocarbons, it is widely used worldwide as a substitute for them. As a gas, it can be utilized in hair sprays, mousses, air fresheners, insecticides, automotive paint, coatings and polishers, rust inhibitors, and as an extractant. High-concentration dimethyl ether can also be used as a **reagent; it serves as a chemical raw material for various products such as organic compounds, pesticides, dyes, pharmaceuticals, and fuels, making its applications extremely wide. In 1995, China’s consumption of dimethyl ether exceeded 15,000 tons per year, yet the country’s production capacity was low; high-purity (>99%) dimethyl ether had to be imported. In 2000, China’s consumption of dimethyl ether reached 20,000–30,000 tons per year. This post was last edited by arta2002 on 2008-1-8 14:51]