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Ethylene Glycol Manufacturing Method
Ethylene Glycol (ethylene, EG) is a colorless, odorless, viscous liquid with hygroscopic and sweet taste. Ethylene glycol is an important chemical raw material, which is widely used in the production of polyester fiber, antifreeze, unsaturated polyester resin, lubricant, plasticizer and so on. This article will introduce the manufacturing method of ethylene glycol.
1. Chloroethanol method
Chloroethanol method is one of the main methods of ethylene glycol production. The method uses chloroethanol as raw material to produce ethylene glycol through alkali hydrolysis, saponification, distillation and other steps. The specific steps are as follows:
1. Preparation of chloroethanol: Ethylene and chlorine are mixed, and chloroethanol is generated by addition reaction.
2. alkali solution: the chlorine ethanol and sodium hydroxide solution mixed, control a certain temperature and pH value, so that the chlorine ethanol hydrolysis reaction of ethylene glycol and sodium chloride.
3. Saponification: Excess sodium hydroxide is added to produce sodium soap from sodium chloride, while ethylene glycol is reacted with the remaining sodium hydroxide to produce sodium acetate.
4. Distillation: the reaction liquid is distilled, ethylene glycol is distilled first, then sodium acetate is distilled, and finally the remaining sodium hydroxide solution is discharged.
2. ethylene oxide hydration method
ethylene oxide hydration method is another manufacturing method of ethylene glycol. The method uses ethylene oxide and water as raw materials, and under the action of a catalyst, undergoes a hydration reaction to produce ethylene glycol. The specific steps are as follows:
1. mix ethylene oxide and water according to a certain proportion and enter the reactor.
2. Under the action of the catalyst, control a certain temperature and pressure, so that ethylene oxide and water ring-opening addition reaction to generate ethylene glycol.
3. the reaction product is separated, refined and other steps to obtain pure ethylene glycol product.
3. Dimethyl Carbonate Process
Dimethyl Carbonate process is a new method for the manufacture of ethylene glycol. The method uses dimethyl carbonate and ethylene as raw materials to produce ethylene glycol through transesterification, hydrogenation and other steps. The specific steps are as follows:
1. Dimethyl carbonate and ethylene are mixed in a molar ratio of 1:1, enter a transesterification reactor, and under the action of a catalyst, generate diethyl carbonate and methanol.
2. The mixture of diethyl carbonate and hydrogen enters a hydrogenation reactor, and under the action of a catalyst, the hydrogenation reaction is carried out to produce ethylene glycol and methanol.
3. Ethylene glycol and methanol are separated by distillation and other separation means to obtain pure ethylene glycol products.
To sum up, the manufacturing methods of ethylene glycol mainly include chloroethanol method, ethylene oxide hydration method and dimethyl carbonate method. Different methods have different advantages and disadvantages and scope of application. Enterprises can choose the appropriate manufacturing method according to their actual situation and needs. At the same time, with the continuous progress of science and technology and the continuous improvement of environmental protection requirements, the manufacturing technology of ethylene glycol is also constantly improved and optimized, and more efficient and environmentally friendly manufacturing methods will emerge in the future.