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Time:14months ago
Source:Transform the World with Simplicity
PTA (terephthalic acid) is an important organic chemical raw material, widely used in the production of polyester, fiber, film and other products. The following is the manufacturing method of PTA:
1. oxidation method
oxidation method is the main method for producing PTA, and its raw material is p-xylene (PX). The reaction principle of this method is to oxidize PX with oxygen under high temperature and high pressure conditions to generate PTA and acetic acid. The specific steps are as follows:
1. PX and acetic acid are added into a reactor while oxygen is introduced, and the reaction temperature is controlled between 180-200 ° C. and the pressure is between 2.0-2.5MPa.
2. The mixture of PTA and acetic acid produced by the reaction is cooled, crystallized and filtered to obtain a finished product of PTA.
this method has the advantages of easy access to raw materials, relatively mild reaction conditions and high product purity, it is widely used in the production of PTA.
2. esterification
esterification is a traditional PTA manufacturing method, and its raw materials are p-benzene dimethanol and diethyl terephthalate. The reaction principle of this method is that under the action of an acidic catalyst, p-benzene dimethanol and diethyl terephthalate are esterified to produce PTA and ethanol. The specific steps are as follows:
1. Add p-benzene dimethanol and diethyl terephthalate into a reactor, add sulfuric acid as a catalyst, and control the reaction temperature between 200-240°C.
2. The mixture of PTA and ethanol produced by the reaction is distilled, crystallized and dried to obtain a finished product of PTA.
the process of this method is cumbersome and requires a large amount of sulfuric acid and ethanol, the production cost is high and has been gradually replaced by the oxidation method.
3. other methods
In addition to oxidation and esterification, there are some new PTA manufacturing methods under research and development, such as photocatalytic oxidation, supercritical water oxidation and so on. These methods have the advantages of mild reaction conditions and environmental protection, but they are still in the laboratory or pilot stage and have not yet achieved industrial production.
In short, the oxidation method is the main PTA manufacturing method, with the advantages of easy access to raw materials, relatively mild reaction conditions, high product purity, so it has been widely used in the field of chemical production raw materials.