Ethylene Glycol (EG) is an important raw material for the production of chemicals and is widely used in polyester fibers, antifreeze, unsaturated polyester resins and other fields. The following is a detailed introduction about the manufacturing methods of ethylene glycol.
I. Chloroethanol Method
Chloroethanol method is a method to prepare ethylene glycol by alkali reaction with chloroethanol as raw material. The method is mature and simple to operate, but the production process generates a large amount of wastewater and exhaust gas, causing large pollution to the environment.
1. Preparation of chloroethanol
Chlorine gas is passed into ethanol, and the reaction generates chloroethanol mixture, which is separated by distillation to obtain chloroethanol.
2. Alkalysis reaction
Mix chloroethanol with aqueous sodium hydroxide, control a certain temperature and pH, and carry out alkalysis reaction to produce ethylene glycol and sodium chloride.
3. Separation and purification
Through distillation, extraction and other separation and purification methods, ethylene glycol and sodium chloride and other impurities are separated to obtain a higher purity ethylene glycol product.
II. Ethylene oxide water method
Ethylene oxide water method is the method of generating ethylene glycol by reacting ethylene oxide with water as raw material. This method has the advantages of easy availability of raw materials, mild reaction conditions, high product quality and so on, and it is a commonly used method for the preparation of ethylene glycol in the industry at present.
1. Preparation of ethylene oxide
Ethylene oxide is prepared by methods such as ethylene oxidation or ethylene chlorination.
2. Hydration reaction
Mix ethylene oxide and water in a certain proportion, control a certain temperature and pressure, and carry out hydration reaction to produce ethylene glycol.
3. Separation and purification
Through distillation, extraction and other separation and purification methods, ethylene glycol is separated from water and other impurities, and ethylene glycol products with higher purity are obtained.
3. Dimethyl Carbonate Method
Dimethyl Carbonate Method is the method of generating ethylene glycol by ester exchange reaction with dimethyl carbonate as raw material. This method has the advantages of easy availability of raw materials, mild reaction conditions, high product purity and so on, and is a more promising method for the preparation of ethylene glycol.
1. Preparation of dimethyl carbonate
Dimethyl carbonate was prepared by reacting phosgene with methanol.
2. Ester exchange reaction
Mix dimethyl carbonate with ethylene glycol monomethyl ether, control a certain temperature and pressure, and carry out ester exchange reaction to produce ethylene glycol and methanol.
3. Separation and purification
Through distillation, extraction and other separation and purification methods, glycol and methanol and other impurities are separated to obtain glycol products with higher purity.
Four, ethylene oxidation method
Ethylene oxidation method is to use ethylene as raw material, through oxidation reaction to generate ethylene oxide, and then the hydration reaction to generate ethylene glycol method. This method has the advantages of easy availability of raw materials, high production efficiency, good product quality and so on, and is a commonly used method for the preparation of ethylene glycol.
1. Oxidation reaction of ethylene
Ethylene is mixed with oxygen, a catalyst is introduced, a certain temperature and pressure are controlled, and an oxidation reaction is carried out to generate ethylene oxide.
2. Hydration reaction
Mix ethylene oxide with water in a certain proportion, control a certain temperature and pressure, and carry out hydration reaction to produce ethylene glycol.
3. Separation and purification
Through distillation, extraction and other separation and purification methods, ethylene glycol is separated from water and other impurities to obtain ethylene glycol products with higher purity.
All in all, there are various manufacturing methods of ethylene glycol, and different methods have different advantages and disadvantages and scope of application. In actual production, suitable manufacturing methods should be selected according to specific conditions to ensure product quality and production efficiency.
