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[Chemical Knowledge]：Manufacturing method and process of diethylene glycol

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Diethylene glycol (Diethylene, DEG) is an important chemical raw material, which is widely used in the manufacture of plastics, fibers, coatings, antifreeze, solvents and other fields. In the field of chemical production raw materials, the manufacturing methods of diethylene glycol mainly include chloroethanol method, ethylene oxide hydration method, ethylene glycol method, etc. This article will detail these three manufacturing methods.

1. Chloroethanol method

The chloroethanol method is an earlier method of manufacturing diethylene glycol, which mainly uses chloroethanol, sodium hydroxide and water as raw materials to generate diethylene glycol through the reaction. The specific steps are as follows:

(1) Chloroethanol is mixed with an aqueous solution of sodium hydroxide, and a certain temperature and pH value are controlled to react to generate ethylene glycol monoethyl ether.

(2) Ethylene glycol monoethyl ether is mixed with an excessive amount of an aqueous sodium hydroxide solution, and the mixture is heated at a temperature to cause a transetherification reaction to produce diethylene glycol. The reaction solution is subjected to neutralization, desalting, distillation and other treatments
to
(3) to obtain a pure diethylene glycol product.

the chloroethanol method is simple, a large amount of waste salt and waste water will be produced in the production process, and the environmental protection pressure is high. Therefore, this method has been gradually replaced by other methods.

2. Ethylene oxide hydration method

Ethylene oxide hydration method is widely used at home and abroad diethylene glycol manufacturing method, mainly ethylene oxide and water as raw materials, through the addition reaction to generate diethylene glycol. The specific steps are as follows:

(1) Ethylene oxide and water are mixed in a certain proportion, a catalyst is added, a certain temperature and pressure are controlled, and an addition reaction is performed to generate ethylene glycol.

(2) Ethylene glycol is mixed with an excess of ethylene oxide, a catalyst is added, and the addition reaction is performed again to produce diethylene glycol. The reaction solution is subjected to rectification, dehydration and other treatments
to
(3) to obtain a pure diethylene glycol product.

ethylene oxide hydration method has the advantages of easy access to raw materials, mild reaction conditions and high product purity, and has become the mainstream method of diethylene glycol manufacturing.

3. Ethylene Glycol Method

The ethylene glycol method is a method for producing diethylene glycol by cracking ethylene glycol. The specific steps are as follows:

(1) The ethylene glycol is heated to a certain temperature, and a catalyst is introduced to crack the ethylene aldehyde and water.

(2) reacts vinyl aldehyde with water to produce glyoxal.

(3) Glyoxal reacts with water under acidic conditions to produce diethylene glycol.

ethylene glycol process is relatively simple, but the production process requires high temperature and catalyst, high energy consumption, and the product purity is relatively low. Therefore, the application of this method is limited.

In summary, the chloroethanol method, the ethylene oxide hydration method and the ethylene glycol method are all common diethylene glycol manufacturing methods, each with its own advantages and disadvantages. In the actual production process, the appropriate manufacturing method should be selected according to the source of raw materials, production scale, environmental protection requirements and other factors. At the same time, with the continuous progress of science and technology and the improvement of environmental awareness, the manufacturing method of diethylene glycol will be more environmentally friendly, efficient and energy-saving in the future.

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