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Industrial production method of oxalic acid

Issuing time:2020-11-14 15:24


The main industrial production methods are: sodium formate method, oxidation method, carbonyl synthesis method, ethylene glycol oxidation method, propylene oxidation method, carbon monoxide coupling method.


Sodium formate method


After purification, carbon monoxide reacts with sodium hydroxide under pressure to form sodium formate, which is then dehydrogenated at high temperature to produce sodium oxalate. Sodium oxalate is then lead (or calcified), acidified, crystallized and dehydrated to obtain finished oxalic acid. The synthetic pressure of carbon monoxide and sodium hydroxide is generally 1.8-2.0mpa. The dehydrogenation temperature was 400 ℃.


Oxidation process


In the presence of alum catalyst, starch or glucose mother liquor was oxidized with nitric acid sulfuric acid to obtain oxalic acid. The nitrogen oxide in the waste gas is sent to the absorption tower for recovery to form dilute nitric acid.


Carbonyl synthesis


Carbon monoxide was purified to more than 90%, and then carbonylated with butanol in the presence of palladium catalyst to form dibutyl oxalate. Oxalic acid was obtained by hydrolysis. This method can be divided into liquid phase method and gas phase method. The reaction conditions of gas phase method are lower and the reaction pressure is 300-400kpa. The reaction pressure of liquid phase method is 13.0-15.0mpa.


Ethylene glycol oxidation


Ethylene glycol was prepared from ethylene glycol by air oxidation in the presence of nitric acid and sulfuric acid. 5. The process of propylene oxidation is divided into two steps. In the first step, nitric acid is used to catalyze the oxidation of nitric acid to give propylene. In the second step, mixed acid can be used as oxidant. Industrial grade oxalic acid dihydrate was produced by propylene oxidation, and the total yield was more than 90%


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